AMA | November 2022

Johan Falk
I can't get rid of the feeling that we're living in a time when a lot is at stake – like what we do now has huge implications for the future of humanity. (I'm thinking of global warming, AI changing our society, increasing we-against-them mentality, China potentially becoming the new super power, and things like that.) This gives me some anxiety, but also makes me want to do things that helps us move in the right direction (whatever that is).
1) Do you think that we're at some kind of crucial point in history?
2) Do you think most people throughout history have felt that they're at some kind of crucial point?
3) Do you have any thoughts on how such a feeling can be harnessed into something good, instead of mostly feeling despair?

The Cyber Monk
I am currently reading volume one of the Biggest Ideas in the Universe. I borrowed the ebook from my local public library, which is how I get practically all the books I read. As a software engineer, I easily make enough money to buy them instead. Assuming that would be financially favorable to the author, do I have an obligation to do so? More generally, can one be so well-off that one has an obligation to _stop_ using certain public goods, or to provide additional support above and beyond what is otherwise expected of a good citizen?

Brandon Wheeler
Has anything discovered by the James webb altered your credence on physics fundamentals?

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John B. Wyman
Do you think it is possible, in principle, for the human brain to discover the "theory of everything"? I think not because the brain is a part of the theory. It's like the so-called paradox: Does the set of all sets contain itself?

Tim Gianitsos
Do you agree with Thomas Kuhn that there will never be a final or definitive scientific account of nature?
He gives the analogy that scientific theories are like organisms in evolution - there is not a "final" organism that evolution is driving toward. He argues similarly that there is not a terminal scientific paradigm but simply those which better allow us to frame certain puzzles.
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Moshe Feder
LIGO's success in detecting gravity waves was one of the great physics achievements of our lifetimes.
I understand that LIGO will now be followed by the LISA project. It will employ three spacecraft orbiting the Sun in an equilateral triangular formation with sides about 1.5 million miles long.
But I'm unclear on how LISA will work. Surely it can't be by the subtle length variations in laser beams used by LIGO. Can you explain the method they'll be using?

Jakob Jongsma
Would you be surprised if a new physical theory with a similar impact as relativity or quantum mechanics turns up?

Sandro Stucki
At the beginning of the latest Mindscape episode, Barry Loewer credits From Eternity to Here as one of two books that introduced philosophers to the idea that statistical mechanics is at the root of all the special sciences, causality and the arrow of time. When you wrote that book, did you hope to get philosophers thinking about this connection? Did you already think of yourself as a (natural) philosopher back then?

Kathi Seeger
In the October AMA you answered a question regarding societal problems. You mentioned, among other things, social injustice and how this could lead to less faith in democracy.
Following up on that:
I think it's a huge flaw in the US system to link health care, child care and college/university education to one's financial possibilities....and I don't see how this could eventually change because of the aim for freedom with very low involvement of the state in people's personal lives and the economy.
How is it that the "American Way Of Life" is such a strong narrative that so many US-people are willing to accept the aforementioned circumstances although so many inequalities are created?

Thewinningticket
If I understand correctly, Einstein learned about Riemannian geometry from a friend whilst looking for mathematics to aid his general relativity quest. Is this a common practice, ie a physicist has an idea and seeks out mathematical friends, colleagues (or literature) for
unfamiliar maths to interrogate their idea further? Could you conceive of a time when you may be writing out ideas for a paper where an AI programme could suggest relevant mathematical theories, concepts etc (a bit like a technical autocomplete of sorts), to provide the author with
more tools than they would have had by their own learnings to explore an idea further?

Herb Berkowitz
When the term “spin” is used in relation to an elementary particle does it mean “spin” in the same sense as a planet or a baseball? Does the particle turn on an axis or create centrifugal force?

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Dom
Noether's theorem says time symmetry leads to conservation of energy. However in general relativity energy is not conserved (citation one S. Carroll, From Eternity to Here). Is it therefore the case that general relativity is necessarily time asymmetric?

Jim Watson
There are various conserved quantities - energy, momentum, angular momentum, charge, etc. And it is explained that these quantities aren't really conserved under certain conditions or properties of the universe, e.g., in an expanding universe, conservation of energy doesn't hold. What would be the properties/conditions of the universe if the conversation of momentum or the conversation of charge (or other conserved quantities) didn't hold?
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Michael
You mentioned in a previous AMA that among your idea of what makes someone an intellectual is someone who is in pursuit of trying to find truth (pointing out how some politicians may be intelligent, but not intellectuals, since, as politicians, they are not trying to figure out what is 'true' and so forth). I am wondering, if living in search of truth is what makes someone an intellectual, does that mean QAnon/conspiracy theorists are intellectuals, since it seems that as 'erroneous' as they are, they seem to believe they are in some sort of pursuit of the 'truth', uncovering what is 'really' true, etc. Or, is it more the case that using the scientific method in the search for what is true is what makes someone an intellectual?

Anthony Rubbo
In the last AMA, you expressed disinterest in the explanatory differences between your notion of Many Worlds and that of David Deutsch's...you were really just content with everyone agreeing on the Math.
It was a bit startling -- it felt like in /Something Deeply Hidden/, you were championing human-friendly explanations & analogues...and did so in several instances, e.g. - spending a nice bit of time on an alternate, human-centric view on The Born Rule.
Has the zeal for uncovering greater descriptive methods around Many Worlds truly waned, was it just an off-day, or have I mischaracterized?

Zach McKinney
In your conversation with Will MacAskill, you two discussed how the plurality and evolution of values is essential to the survival and future wellbeing of humanity. What would you hypothesize to be the *core values* that enable human societies to survive and thrive in increasingly hazardous times?
How might you approach the problem of quantifying and modeling the spread of ideas and evolution of values at different scales within and across cultures?

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James Maddox
At the end of the podcast with Antonio Padilla, you were discussing if the universe is finite or infinite. As someone who agreed with your arguments on the “naturalness” of infinity, I was shaken by his rebuttal of “well, which infinity then?”. Is there any lifeline you can throw to those of us disturbed by the prospect of living in a finite universe?

Eric Chen
What's your own take on the last question you asked Tony Padilla: Is reality finite or infinite? What are the best reasons for taking either view on this question?
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Derek Bayne
I'm really enjoying the new book, and for what it's worth I think it succeeds in making physics accessible to a total novice like myself. Thank you for writing it. NOW THE QUESTION: have you dressed up for Halloween in the past, and, if so, which of your costumes are you most proud of?

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Ken Wolfe
Presuming such things exist, if we found there was a primordial black hole near enough to send an orbiter, what experiment would you most like to see done and what question would you be hoping to answer.

Roo Phillips
If a black hole were able to come close enough to our solar system that we could send spacecraft out to it in your lifetime, what questions would you want to try and answer that we aren't able to get at easily with black holes too far to reach with a spacecraft?
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Robert Ruxandrescu
I had a bunch of scientific questions on my mind but I’m going to change that topic and ask something else, something that is important for me: bullying. When I was little I was bullied a lot, both in elementary school and in high school - the main reason was that I was considered the “school’s nerd”. Have you personally had to deal with bullying? If so, what did you do and what was the reason?

Sheldon Sillyman
I am guessing that you might consider evolution an emergent phenomenon. And, if so, would you then say that this emergence implies a strong possibility that evolution would operate throughout the universe? Is emergence universal and how does that work for such fuzzy concepts like culture and agency?

Michael Mohnhaupt
which individual steps are happening when two particles become entangled (or disentangled), and how long does this process from not entangled to entangled approximately take?

Jay Peters
PRIORITY QUESTION
What is the nature of the "interaction" among particles that is said to give rise to quantum entanglement? Is it just a matter of spatial proximity, such that the closer together they are the greater the level of entanglement? Or does there have to be some sort of 'event' (a quantum analogue of a handshake or a nod) that includes both and that establishes their entanglement?

Cooper
When you talk about other universes with "different laws of physics", do you just mean their fundamental constants have different values? Or do you mean completely different underlying equations like different terms in GR or different gauge symmetries in QFT?

anonymous
The Standard Model is called the most successful theory ever. Well, isn't more like the most successfully tuned theory ever? Every time a result comes in, some parameters are tuned to produce that value and ranges for the other parameters may further constrained. No wonder SM agrees with experiment.

Keith
I happened to see that the 76ers are playing the Wizards tonight in your neck of the woods as they say. Any particular fun in-person 76ers games memories you feel like sharing, as a kid or whenever?

Andrew J
Keeping in line with your thinking about “social systems using ideas from physical systems.”
What role, if any, do you think entropy has to play in macro societal actions? Is human progress doomed to simply shift “disorder” to whatever system we have the fewest problems with? Be it the environment, international trade, etc.

Brendan
Do you think your deep understanding of math and physics enables you to quickly (or easily) comprehend other technical fields such as computer science? For example, are you able to understand machine learning and/or computer programming with little difficulty?

Brian Mapes
Numerology: is there anything fundamental about 10 beyond (4 fingers + opposable thumb)x2 being biomechanically successful? And even spooo,oookier: wassup with 10^10? Bits in the genome, neurons in the brain, stars in the galaxy, galaxies in the universe, "enough" data for ML, etc.

Henry Jacobs
Lottery voting is an election system wherein a single voter is randomly selected, and his vote decides the election. Here are some positives:
1. It's a proportionate representation system.
2. Voters have more power than in a plurality based system (if you model the voters as biased coins, the mutual information between a voter and the election outcome decays quadratically with population size. In plurality systems the decay is exponential.)
...
As you can tell, I'm a fan of this system. There are issues. Nonetheless, do you think this is a good starting point?

Dory Vinett
Not a question, but I think you’d like knowing that my cat associates your voice with treats. I often listen to Mindscape while making dinner, and now when Bastet hears your voice at other times she runs to the kitchen.

Johan Falk
What mathematics do you think everyone should learn in school, regardless of career path?

Nichael Cramer
Concerning the “Past Hypothesis” (I.e. the hypothesis that the universe was initially in a state of extremely/maximally low entropy):
Is there a way in which that might be tested?

Roy Thompson
Priority question. When black holes merge, how is the mass converted to gravitational waves? Any implication for the black hole information paradox?

Schleyer
You’ve said that you take the universe to be a closed system, thermodynamically. I know some other physicists don’t, though I think they are outliers. Can you describe the status of our knowledge here? Being unbounded, expanding and maybe infinite, the universe doesn’t seem much like a piston chamber.

martha hinrichs
What sociocultural rituals and ceremonies do you/have you ever participated in? (i.e. were you married by a religious officiant? do you watch fireworks on the 4th of July? fast during Ramadan?)

Brent Meeker
In Mindscape 63 | Solo: Finding Gravity Within Quantum Mechanics you speculated that there are only finitely many DoF in a given volume. Wouldn't this imply that there are also only finitely many possible states and so there would be a smallest non-zero probability of any possible event.

Sean Bentley
Loved your episode on large numbers with Tony Padilla. I'm not as studied on the holographic principle as I could be, so apologize for the predestrian question... When removing gravity, why do we go from 3 dimensions of space down to 2 and not 4 dimensions of space-time down to 3?

Roman Leventov
In the context of the show with Barry Loewer, specifically when you discuss how the laws of physics can explain anything: do I understand correctly that Deutsch & Marletto's philosophy of science in Contructor theory is in the middle between Humean and anti-Humean (aka God) views? That is, counterfactual principles are "event-producing", real, and serve as explanations, whereas dynamical laws which can, as Deutsch and Marletto conjecture, be derived from fundamental counterfactual principles, are "mere" descriptions.

Simon Liubinas
Various spiritual and philosophical traditions claim that the universe has a non-dualistic nature; that ultimately the universe and everything in it is one indivisible… “thing”, and that the apparent diversity that we see is mere illusion.
I’m not suggesting that ancient philosophers actually discovered quantum field theory, but theology aside, is it scientifically valid to think of the wave function of the universe as the only one “thing” that actually exists? Can we even think of individual objects as being seperate from each other if ultimately everything is a manifestation of a single field?

Krzysztof Pieranski
I love my cats, I enjoy their unique characters and admire their ingenuity, but at the same time, I see their intellectual limitations. As they can't grasp complex concepts, it seems that the jump from a cat to human intelligence is a qualitative one. Then, there are quantitative differences between individual people's intellectual abilities. But do you think there is another level, a qualitative jump above human intelligence? Or do you think that for some reason (language? ability to generalize? being universal Turing machines?) we are at the most general level already and any progress from here is (just) scaling?

Chris A
Somewhat moot now, as he's thankfully been voted out, but had Jair Bolsonaro been re-elected, would it have been ethical to assassinate him, to prevent his continued wanton destruction of the Brazilian rainforest, on which so much of the world's biological diversity depends?

JOHN PERRY
I have just been catching up and listened to your "Secrets of Einstein's Equation cast. It seems inconceivable to me that Euclidian geometry was considered to be the "answer" without serious question for so long. The sphere for example would have been a "well known" object to Euclid himself. With the obvious level of historical intellect available, why do you think it survived as the single solution for so long?

Paul Cousin
How many back and forths do your papers have to make on average between you and your reviewers? On which parameter does this depend the most (e.g. topic, length of the paper, prestige of the journal)?

Declan Brennan
Does History have a direction?
Some looking at the Ukraine situation think that Russia doesn't realize the era of colonialization is over. Others feel that history has no more of a direction that does evolution. If it doesn't have a direction, does it at least move through phases? If it has a direction, can individuals influence it or are we all just flotsam on the tides of historical necessity?

Malte Ubl
Given the assumption that the world was created as a random quantum fluctuation, what is the probability that it "just now happened" rather than happened in the past and from there dynamically evolved to the current state?

Connor Shafran
Unless I've miscounted, you've only had three episodes that discuss climate change as a main topic, which is just about 1.4% of your total episodes, with the most recent being released ~3 years ago. It seems like there are lot of smart people with expertise in climate science who are saying that climate change is the most urgent issue facing humanity at the moment. Is there a reason that you don't talk about it more these days?

Tarun
In your recent discussion with Barry Loewer, you seemed to agree that the Humean view in relation to the laws of nature is the correct one, in comparison to what you called the “god view”. However, I was then surprised to see that in the last PhilPapers survey, the majority of philosophers stated they accept or lean towards the non-humean view. This is despite the majority having atheistic views and subscribing to naturalism. Why do you think that is?

James Alan
Briefly in your debate with Dr. William Lane Craig, you mentioned that modern physics doesn’t use Aristotelian notions of cause and effect. Is there a place in the literature that clearly expressed that view? Such a citation would be valuable in the corners of the inter webs where atheists hang out.

Jimi
Is there an asymmetry between position and momentum in the Hamiltonian? If so, does that mean they aren't as practically equivalent as it sometimes seems?

Joshua Hillerup
Do you think poetic naturalism could be applied to ethics? For instance, could be some sort of "fundamental" consequentialism that's about as useful for making actual ethical decisions as the standard model is for engineering a building, but it could be used to "build up" other ethical theories more specific to given domains, in a similar chain to what we see in science?

Paul C Conti
I was wondering, now that you are at Johns Hopkins, if you would be given any preference in submitting an Observation Proposal for the JWST ? If you could submit an Observation Proposal to the JWST committee, what Cosmological or Astrophysical question would you consider investigating ?

Nalita S
What is, from your perspective, preventing us from finding dark matter, given its immense influence. Do you think we will ever be able to “spot it” like we did other elementary particles?

Brent Jones
I teach AP Chemistry and AP Physics at a rural high school in West Virginia, and I absolutely love going to work everyday. Now that you’re teaching again, I’m curious to know what you love most about teaching.

Dave
According to black hole holography, does Hawking radiation convey information about the state an object was in when it hit the event horizon only, or rather a history of all of its states inside the event horizon until it hits the singularity?

Redman
On atheism, does a strict materialist who rejects not only traditional concepts of a deity, but any higher organizing principle whatsoever, assume the burden of proof?

Jeff B
Imagine that a simple object like a paperclip is floating in empty space. For the sake of argument, suppose that the paperclip is shielded from interacting with the environment in any way. Now we could imagine waiting some amount of time and then observing the paperclip. Am I correct in saying that the longer we wait, the more branches will be created when the paperclip is observed? If so, is this mostly due to the larger number of radioactive decays the paperclip has undergone, or is it mostly due to the paperclip gradually spreading out over Hilbert space?

Chris Murray
In a closed universe, if you put many black holes close together in a straight line all the way around the universe, could they merge to become a "black tube" with a stable cylindrical horizon? What would that be like?

Casey Mahone
Experiences of aesthetic beauty can sometimes feel transcendent and divine, but from a materialist standpoint these experiences must be rooted in our evolution. What do you speculate is the evolutionary basis for these sorts of overwhelming mystical or artistic experiences?

Floyd Aldrich
Can you explain how a dragon would breath fire in the fantasy world?

Christopher Backs
I recently read a New York Times article about a German heiress leading a movement to have massive inheritances go almost completely to taxes and redistributed by the government, the thought being that, redistribution vis philanthropy reinforces existing power structures by allowing the ultra wealthy to decide where there money goes. I like the spirit but feel like it puts a lot of faith in government to use this money well and actually reinforces international power dynamics by keeping money in countries with more ultra rich people.

Peter Solfest
In episode 200, you seem to make the argument (paraphrasing) that considering yourself as a bolzman brain is cognitively unstable, so we shouldn't think of ourselves as bolzman brains, and thus should assign lower credences to theories that predict there are a lot more bolzman brains than other observers. I follow the logic to not thinking of myself as a bolzman brain, but why should that give me the leverage to lower my credence about cosmological theories that predict bolzman brains? In other words, I get that I should behave as if I'm not a bolzman brain for practical reasons, but why should that give me theoretical grounds to make any statements about which theory is better?

Firas
I noticed that whenever scientists talk about the state of the universe and associated big theories they never really add the small asterisk that its all from the perspective of humans and from our location in space. Do you think this creates a form of scientific absolutism where we fail to recognise that the rules that govern our reality only really make sense from our observer status from our perspective? We may not be able to say what things will look like for another observer 10 billion light years away, but surely we can at least acknowledge that the universe from their perspective is quite different and therefore the science that we assume governs all localities in the universe might not be applicable to them?

krathorlucca
Why do you think many worlds is still not the consensus view for the foundations of QM?

Steve Glore
Do you have any anecdotes about your interactions with William Lane Craig? I've seen quite a few WLC debates and yours is probably the one that has challenged his scripted talking points the most effectively - you had some help from Alan Guth as I recall 🙂 What are your recollections of the times you have debated him, any chit chat before/after, thinking back are there any additional things you wish you had said or things you would now put differently?

Claudio
I lived 32 years in a country with mandatory voting and 20 in a country where voting is not mandatory. I strongly favour making voting mandatory. My rationale is that for proper democracy, the government must be representative, this is, its composition should be as proportional to the people as possible. What's your position on mandatory voting?

Brian
Antonio Padilla said we can't picture Graham's number because it contains too much information. But then I wondered: can you picture pi? There aren't enough atoms in the universe to do that in your head either. But we have it defined. Same for Graham's number. Maybe the question is: what is the significance/are there any implications from the fact that we can't hold it fully in our heads?

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James Swift
I sometimes struggle with how mathematicians use the phrase “solve the equation”. It’s easy to understand when someone says “solve F for x” but when just generally stated statements like “Schwarzschild solved Einstein’s equation” I feel a little lost. Can you give guidance about how to understand such statements? What’s being solved? Is there another way to describe what’s being done here?

Billy Westom
I’m trying to learn some basics about Einstein’s field equations, and I feel I am missing something simple in my understanding of the significance of them before and after they were “solved”. Were Einstein’s equations in 1915 simply incomplete but still obviously important? What does it mean for an equation to be revolutionary without solutions yet found? I may just be misinterpreting the idea of a “solution” in this context. Thanks for the great content!
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Brendan Hall
Do you ever do problems/exercises from a textbook when you’re trying to learn a new subject these days?

Eric Stromquist
On the question of probability in the Everett interpretation, the leading ideas from you and Sebens, and from Wallace and earlier Deutsch, all successfully explain why the Born rule should work but they don’t explain the mechanism. How it is that the great majority of, or the greatest measure of, observer moments with their memories of, say, a sequence of measurement results, end up distributed in the wavefunction so that an observer chosen at random has usually observed just about the right quantum statistics? My guess is that this “how” question involves something like Vaidman’s “measure of existence” idea, which I take to mean that the branching observers of a given measurement sequence are distributed with close to uniform density in some space or manifold that’s related to Hilbert space in a way where most of its volume corresponds to having seen sequences with about the right statistics. My question is, does any of this make sense to you, and do you agree we need an answer to what I call the “how” question?.

Andrew Goldstein
I read things like the October 30th Washington Post editorial which tried to provide some insight into the volatile activity of the stock market and the fortunes of the mega-wealthy . It leaves me even more confused. Therefore, I wonder whether you see any potential for more sophisticated understanding that would give us better knowledge how to forecast the complex social behaviors and interactions observed in humans but are poorly understood?

Jim Murphy
I've developed a hobby of creating cellular automata and watching the emergent results of various rules. The vast majority of the rules seem to produce a chaotic static without any obvious complexity emerging. However, I wonder how much this is a result of my limited computational power and "world" size, versus the inherent properties of the automata. Do you have any intuition for how often rules that appear chaotic at a small scale will create emergent complexity on a larger scale?

Terrible Turnip
What is your view on how specific a fundamental theory should be to ‘feel right’? It seems there is a paradox of sorts: If one finds a theory such that there is only one viable self-consistent possibility then that would seem very strange. On there other hand if there are a huge range of possibilities, that seems to make people uncomfortable - in that then you end up using anthropic principle type arguments to justify one’s observation of this particular universe.

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0:00:00.0 Sean Carroll: Hello everyone, and welcome to the November 2022 Ask Me Anything edition of the Mindscape Podcast. I'm your host, Sean Carroll.

0:00:06.9 SC: So I don't know what's going on in your infosphere these days, but in the corners where I hang out, people are kind of obsessed with the idea of what's happening to Twitter with Elon Musk buying it. I'm very active on Twitter, pretty active, a couple of tweets a day maybe on average. Not even everyday do I do it. I know there are some people who do dozens or hundreds a day, I'm not in that super level, but it's valuable to me, Twitter. It's valuable to a lot of people who are journalists and writers especially. I've met friends on Twitter is an important thing, it's also a bit of a mess. It's completely unmoderated. I don't... It's not completely unmoderated, that's not true, but it's largely unmoderated. I'm not thinking about hate speech and things like that, I'm thinking about just dumb goofy comments that people leave. Anyone can come in to your Twitter thread and say something which doesn't always lead to the best conversations.

0:00:58.3 SC: So I've always thought of Twitter as extremely useful, but useful, not for debating deep issues, but for pointing out interesting things, making a wry comment or a joke, having some fun, sharing pointers to the rest of the world is the most important thing that Twitter does, and people complain that it's not a better discussion for them and it was just never meant for that in my mind. But anyway, with Elon buying it, people are worried that it's gonna change somehow, and I honestly don't know whether it will or not, I think it certainly will change somehow, I don't know whether it will be dramatic or whether we will a year from now laugh that we were all worried about it, but it just reminds me that there's a certain familiarity to these kinds of things. There's a lot of people who are saying, well, "I'm leaving Twitter, I'm going to Mastodon," or something like that.

0:01:47.5 SC: And it could very well happen, there's nothing keeping everyone using Twitter all the time, there's certainly been other social media sites or other things on the internet that people have left. I've basically left Facebook, years ago, and I didn't mind that at all. There's some sadness because I don't get to see pictures of my friends or reminders of their birthdays and so forth, but you move on and you find other things.

0:02:11.2 SC: So Twitter could die. And again, regardless of your feelings about whether Elon will bring that about, it's a reminder that these things that become very important don't last forever, and that in turn is a reminder of the fact that we are living in a time in history where we're really nowhere near equilibrium, right? Things are changing very, very rapidly. And that makes it very, very hard to predict the future, 'cause it's always hard, but especially hard because today is different than yesterday, and it's very hard to extrapolate or think that anything about the current state is typical or permanent or anything like that, and it's hard to wrap our minds around that, or the human brain is just not quite built for coping with changes on such a grand scale, on such a rapid time scale, and thinking about what they will mean for time scales beyond our actual human lives.

0:03:05.5 SC: So I wanted to point to that and I remembered that there was a question in today's AMA that actually got to this, so I'm gonna do something I don't usually do, which is to ask the question here in the intro and then we'll move on, but Johan Falk says, "I can't get rid of the feeling that we're living in a time when a lot is at stake, like what we do now has huge implications for the future of humanity, I'm thinking of global warming, AI, increasing "we against them" mentality, trying to becoming the next new super power things like that. This gives me some anxiety, but also makes me want to do things that help us move in the right direction, whatever that is. So number one; Do you think that we're at some kind of crucial point in history? Number two; Do you think that most people throughout history have felt that they're at some kind of crucial point? And number three; Do you have any thoughts on how such a feeling can be harnessed into something good instead of mostly feeling despair?"

0:03:55.0 SC: Well, on the third one, the feeling good, I'm not so sure that I have any good thoughts. I think that it can. Different people will react differently to this feeling that things are at a crisis point or at an inflection point or something like that, some people will be energized by that, leap into the fray and try to make things better. Some people will be overwhelmed by it and retreat and try to find a safe place. And I can't criticize either way, I think that's a difficult question that individuals are going to approach differently. I do have opinions about the first two versions of the question, do I think that we're at some kind of crucial point in history? I would say yes and no. Well, actually let me group that together with the second one, which is, do you think that most people throughout history have felt that they're at some kind of crucial point?

0:04:38.3 SC: Maybe they have, but I would argue that there is something different about the present time for two reasons. One is because, like I just said, things are changing rapidly. Think about just the recent podcast with Will MacAskill or Brad DeLong, really impressing upon us the rapidity of rates of change, and we've had plenty of podcasts in the past few years that make this point in one way or the other. But the other point is that we're more powerful than we used to be. The physical world is full of tremendously large and potentially destructive or constructive energies, and technology has given us the ability to harness some of those energies in ways that we haven't before. Part of this is as simple as we're much more connected. If you're on Twitter, it's much easier to know what is going on in Iran at an up-to-date minute-by-minute basis than it would have been back in the day, just a few decades ago.

0:05:35.9 SC: But another part of it is that we can do tremendous damage to the planet, whether it's nuclear war or climate change or potential biological hazards one way or another. Whether or not you are of the belief that the COVID-19 virus had something to do with testing in a lab when it originated, there's no question that something like that could happen, that human beings could engineer something that could be way more devastating than COVID-19 has been. So I think we have a lot more leverage now over the whole globe than we ever used to, and so I think we are justified in thinking of our current point in time as a crucial point.

0:06:18.5 SC: Now having said that, it might seem much less crucial than a point 100 years from now seems. Once we get to 100 years from now, because presumably our ability to affect the world is just gonna go up, but certainly compared to what was going on 500 years ago, you can easily imagine human beings changing our future history in a dramatic way now, compared to 500 years ago or 5000 years ago or whatever.

0:06:45.0 SC: So I do think it's right to take this seriously in a very, very localized sense. For those of you here in the US, you know that we're right next to our election day, mid-term elections. I go on all the time here about democracy and how democracy is under threat and how people don't really appreciate it, and one of the ways it's under threat is that there's a lot of people on the ballot, even though there's not a presidential race, there's a lot of races for things like Secretary of State of some individual state, the person who is in charge of counting the ballots and sending the results forward to Congress or to wherever, so a lot of the mess that we had two years ago was eventually brought up short by good-hearted bureaucrats, [chuckle] good-hearted people in positions of responsibility saying, No, we are not going to let this election result be overturned. If the election results this week go a certain way, that might no longer be the case two years from now.

0:07:49.9 SC: And the United States is one of the longest continuously operating democracies in the world right now, there's no reason why that has to keep going. So that's just yet another way in which things can change very dramatically. So I think it's perfectly legit to think that we are in a historically crucial time. Now, what are we gonna do about it? Well, I think there's a bunch of things to do about it, none of them... Whenever you say, what are we gonna do about it, the question is, who's this we were talking about? Like literally, you and me, we're not gonna do that much. I can come on my podcast and complain about threats to democracy or biological terrorism or whatever, and the world is not gonna change that much because of my thoughts on that being spread throughout the various podcast apps, but collectively, we could do a lot.

0:08:42.4 SC: The thing that's most depressing to me about the democracy side of things is that democracy isn't that popular, this is literally true in the sense that political operators who are doing polling for candidates are saying, what are the big themes that would resonate with you this election season? And safeguarding democracy is always near the bottom for both Democrats and Republicans. And it's in a more abstract way, if you ask people about, would it be better if we just had one really good person in charge rather than this messy having people vote and have their say thing.

0:09:20.0 SC: There's a lot of people who would just rather have one competent person in charge. Deep down democracy is not that popular, and it's almost a miracle has lasted this long. So what can we do about that? Education, we take a lot of things for granted. When I grew up, democracy was just a good thing, and we knew that was a good thing, and we didn't really dig that deeply into it. Look, I'm always afraid when someone says, "What should we do about it?" That I'm just gonna say, "We should do all the things I like doing," [chuckle] and that's generally the way that people go, but one of the things I like doing is being careful about ideas, digging into them very, very carefully.

0:10:02.0 SC: On Twitter, I pointed out that free speech, the phrase free speech is being used as a cajole on this side and that side, and whatever, and what it does is it just dumbs down the discourse. Free speech is crucially important, but it's also not simple, it's complicated, and you can listen to various podcasts I've done, Teresa Bejan is probably the most on point here, but we all agree when push comes to shove that certain kind of speeches should not just be spread all over the place and certain kind should be unfettered and drawing the line is very difficult. And understanding the philosophical justifications for their being aligned, and for their being a value to free speech, it's all very difficult and nuanced, and so I think we should not take it for granted. I think we should talk about it and think about it and decide why we think this is such a big idea. If we had a better idea why we thought that free speech was so important, which I do, we'd do a better job of understanding how to protect it in ways that are compatible with other values that we would also like to protect.

0:11:06.1 SC: There's no absolutism here. There's many values that we care about, and we wanna balance them off against each other, and that's hard and requires thinking. So I don't know, Johan if that's a helpful answer or not, but I think that each of us individually can take the responsibility to be a little bit less simplistic, be a little bit less glib. I'm always going back to the podcast I did with Thi Nguyen, who was a really really... That's a very influential podcast for me, where he points out the seductive-ness of simplicity and clarity and gamification and how that leads into conspiracy theories and things like that. But even if you're not in a cult or a conspiracy theory, everyone wants simplicity, they want clarity, and the world doesn't always provide it, and values like free speech versus other values is a situation where it's not simple, and you have to embrace that and honor that, that's... But then again, I'm just saying that people should be more like me, which is sort of the cheap and easy thing to do.

0:12:06.4 SC: Anyway, I'm not in charge. No one is putting me in charge of Twitter or nuclear war or climate change or anything like that, but at least we can keep the conversation going, maybe make everyone's thoughts about these issues a little bit more clear and helpful and do our little tiny part in that way, with that quasi crypto optimistic note. Let's go.

[music]

0:12:47.5 SC: The Cyber Monk says, "I'm currently reading volume one of The Biggest Ideas in The Universe."

0:12:52.7 SC: Good for you, Cyber Monk. I hope everyone is out there reading the book, you know it's November, so there's a whole bunch of gift-giving oriented holidays coming up. The Biggest Ideas in The Universe makes a great gift for anyone in your family. So anyway, the question continues, that was my little editorial comment. "I borrowed the e-book from my local public library, which is how I get practically all the books I read. As a software engineer, I easily make enough money to buy them instead, assuming that would be financially favorable to the author, do I have an obligation to do so? More generally can one be so well off that one has an obligation to stop using certain public goods or to provide additional support above and beyond what is otherwise expected of a good citizen."

0:13:35.3 SC: As an author, I often joke that what I really care about is not people reading my books, but just people buying my books. That's what helps. But guess what? It is a joke, I'm just kidding. I hope that that comes through very clearly. I think it is completely fine with me if you or anyone else reads the book at public libraries. I'm a huge fan of public libraries. My initial inspiration to fall in love with science came from hanging out in my own local public library, so by doing that in some way, you're supporting, maybe even better if you turned it in late so you can pay a little late fine, and in that way give a little cash to your local public library.

0:14:13.7 SC: I appreciate the inclination here that you're sort of pointing to, are you doing the best good for the world by getting an e-book from the local public library, and maybe arguably not. Again, I'm also someone who makes enough money, I have a job, a full-time job, I'm pretty comfortable in that way. I like money, I like making more money, and I do things to make more money, and those things incentivize me doing things that make other people happy, but I'm not struggling near the poverty line or anything like that, so among all of the authors who you could support by buying their books, I should be low on the priority list. If you are someone I think who is living comfortably enough that you can, in some sense, afford to give a little bit more of your income than is absolutely necessary, then I think that's a good thing to do.

0:15:07.7 SC: I don't think you're under the obligation to not use the public library, but maybe the money you would have spent on a book, give to some charity or something like that, give to some worthy cause. We talked about that also on the podcast, and I have, I think at the beginning of next month's AMA, I'll do a little update on the state of... If you remember back, when Joshua Green was on the podcast, he promised to give a sort of matching donation kind of thing to Mindscape listeners who donated to Giving Multiplier, and that actually worked out really, really well. So I'll have some good news to share with the community there, but something like that, I'm not gonna judge people on whether or not they give to the charities that I think they should be giving to. I think that we're all trying our best here, if you want to give to your local puppy shelter, that's perfectly also okay with me.

0:16:00.1 SC: Brandon Wheeler says, "Has anything discovered by the James Webb Space Telescope altered your credence on physics fundamentals?"

0:16:07.6 SC: So no, and my credence is that it's extremely unlikely that anything discovered by the James Webb Space Telescope will alter my credence on physics fundamentals. That's just not what the telescope was designed to try to do. When you look at the universe in a new way, you can always be surprised, and we frequently are surprised, but the kinds of things that Webb is looking at, whether it's early galaxy formation or searching for evidence, looking at atmospheres of exoplanets or something like that, none of these are gonna change physics fundamentals. There's other kinds of science that we're gonna learn about. But that's okay, just 'cause something is big and exciting doesn't mean it's gonna give us new information about the fundamental laws of physics.

0:16:51.3 SC: I'm gonna group two questions together, one is by John B. Wyman, who says, "Do you think it is possible in principle for the human brain to discover the theory of everything?" I think not because the brain is part of the theory, it's like the so-called paradox, does the set of all sets contain itself. And then Tim Gianitsos says, "Do you agree with Thomas Kuhn that there will never be a final or definitive scientific account of nature? He gives the analogy that scientific theories are like organisms in evolution, there's not a final organism that evolution is driving toward. He argues similarly, that there is not a terminal scientific paradigm, but simply those which better allow us to frame certain puzzles."

0:17:30.5 SC: So they're not the same question, Tim is asking, Do you think that there is a definitive final account theory of everything, if you wanna put it that way. And John is asking, do you think that we could ever find it if it were there, I presume. And so I do think that there is a theory of everything because there's the universe, the universe exists. There is something that the universe does, and whatever that is, there's a description of that, that would be the theory of everything. That's it. I see zero reason to doubt that, I think it'd be much, much harder to imagine sort of a metaphysical stance in which you literally could not frame or describe what the universe does with perfect accuracy than one in which you can, we're just not there yet. The fact that we're not there yet is the least surprising thing in the world. The surprising thing is how much progress we've made toward it. So I absolutely think that there is some final definitive scientific account of nature.

0:18:25.0 SC: Do I think that the human brain can discover it? There, maybe, maybe not, but I would... If I were forced to, I would lean toward probably. [chuckle] And I don't find... I get the worry that you say the brain is the part of the theory, therefore we're trying to describe it, but that's a little bit off the mark here in terms of what we're trying to do here, because a theory of everything is not... Or a scientific theory of everything is not supposed to be a complete and precise specification of the world, it's supposed to be a complete specification of the patterns, the laws that the world obeys. So when I say F equals MA, force equals mass times acceleration by Isaac Newton, that is a pattern that is obeyed by every planet in the solar system and every star in the galaxy, etcetera. I don't need to re-discover it or restate it every time. That's the great thing about the laws of physics. That's something I dwell upon at great length in The Biggest Ideas in The Universe, the universality of these laws. So we would think that the human brain obeys the theory of everything, whatever it is, but that's no obstacle at all to the human brain discovering it.

0:19:41.5 SC: Mosho Feta says, "LIGO's success in detecting gravity waves was one of the great physics achievements of our lifetime, so I understand that LIGO will now be followed by the LISA Project, it will employ three spacecraft orbiting the sun in an equilateral triangle formation with sides about 1.5 million miles long, but I'm unclear how LISA will work. Surely it can't be by the subtle length variation and laser beams used by LIGO, can you explain the method they'll be using?"

0:20:09.1 SC: Well, I can explain at the level of a theoretical physicist, which is not very deep, there's an enormous amount of technology, delicate, highly advanced design development going on in LISA that... This is a project that is years in the future, not one that's gonna happen any time soon, but it will be a great way to look for gravitational waves in a completely different wavelength regime than LIGO was able to do. But the short answer is, it is the same thing that LIGO does, because LIGO doesn't put down a meter stick and then compare the length of those meter sticks to the time it takes light to travel or anything like that. What LIGO is doing is firing lasers in two different directions, firing them in one direction and then another perpendicular direction, and then tuning it in such a way so that if there is no gravitational wave passing by, the two returning laser beams interfere with each other.

0:21:08.4 SC: So this is a feature about waves, where you can have one wave and another wave, and then you combine them and you get zero wave, at least at a particular point in space because where one wave is going up, the other wave is going down and vice versa. And what that means, what that technique means is that you don't even really need to know the actual distance that the light beam travels to a great precision because all you're looking for are slight variations of that distance. Because if the distance varies in one direction versus the other direction, that complete perfect cancellation of the laser beams will go out of whack a little bit, and that's exactly what LIGO looks for, and that's also basically, roughly speaking, what LISA will do. You have three spacecraft, then you're bouncing from one of them, your bouncing lasers at one and the other one, and you're bouncing them back and then you're trying to look for that sort of interferometry, the interference of the laser beams.

0:22:08.8 SC: So LIGO stands for Laser Interferometer Gravitational wave Observatory, LISA stands for Laser Interferometer Space Array. I don't know what the A stands for, to be honest. But the point is, they're both Interferometers using lasers, that's why they both have the LI in them. So it's basically the same idea.

0:22:30.2 SC: Jacob Johnsma says, "Would you be surprised if a new physical theory with a similar impact as relativity or quantum mechanics turns up?"

0:22:38.8 SC: Well, that's a very good question actually, because it depends precisely on what you mean by surprised. In the long term, I would be not at all surprised that there lurks out there, a better theory than either relatively or quantum mechanics, that will be similarly revolutionary. But in the short term, if in my lifetime, that's what I mean by the short-term, I would be pretty surprised. And the reason is basically just that relativity and quantum mechanics do really well. There's no lingering anomalies or anything like that, there are puzzles, there's the puzzle of the origin of the universe, there's the puzzle of the cosmological constant value, the hierarchy problem in quantum mechanics, and the electroweak theory of particle physics and so forth.

0:23:27.1 SC: There's little puzzles and we need better physics to account for them, there's no really strong evidence that the better physics we need to account for them is completely new and outside the realm of relativity and quantum mechanics, it might be, but that's a different situation than we had a circuit 1900, where we had things like the structure of the atom and black body radiation and so forth, were just strictly incompatible with what we thought we knew about classical mechanics, and so that led to a revolution. Maxwell's equations and Newton's equations for gravity were strictly incompatible. And so relativity had to be invented.

0:24:07.2 SC: So usually the way that physics or other sciences actually make progress is by trying to explain observational or experimental anomalies, and right now in fundamental physics, we don't know of that many such anomalies. You can say, "Well, there's dark matter." Sure, but it's so easy to explain dark matter within the current paradigm, we don't know what the right explanation is, but that's very different than saying we don't have any way of explaining it. So I think that if there is a better theory, it might take a while to figure it out, but I'm willing to be surprised and would certainly be very happy if I were.

0:24:43.3 SC: Sandro Stucki says, "At the beginning of the latest Mindscape episode, Barry Loewer credits From Eternity to Here, as one of the two books that introduced philosophers to the idea that this stucco mechanics is at the root of all the special sciences, causality and the arrow of time. When you wrote that book, did you hope to get philosophers thinking about this connection, did you already think of yourself as a natural philosopher back then?"

0:25:06.9 SC: So I... Barry did say that, and part of it maybe is him being polite. I don't wanna know... I don't wanna speculate as to exactly how influential my book was in the philosophy community, Barry liked it. He's one person. But whether or not that's true, I did certainly have in mind addressing questions that are of interest to both physicists and philosophers, that was already true. In fact, The Arrow of Time was basically what got me into Foundations of Physics and Natural Philosophy. I liked philosophy from back when I was an undergraduate in college, but I liked moral and political philosophy, that's what I actually studied.

0:25:46.3 SC: The philosophy of science stuff was too much about theory change in methodology, which was interesting, but not anything I wanna do for a living. When I started thinking about inflation and the arrow of time, and Roger Penrose's critiques of inflation and things like that, and I wrote my paper with Jennifer Chen about the arrow time, that's the first time when I was really introduced to the whole community of people working on Foundations of Physics in a serious way. Most of whom are philosophers, but some of whom are absolutely physicists. So it's absolutely intentional that the book that I wrote was one that addresses issues that are of common interest to physicists and philosophers, and I'm glad that some of them read it and got something out of it.

0:26:32.6 SC: Kathy Seager says, "In the October AMA, you answered a question regarding societal problems, you mentioned among other things, social injustice, and how this could lead to less faith in democracy. Following up on that, I think it's a huge flaw in the US system to link healthcare, childcare and college university education to one's financial possibilities, and I don't see how this could eventually change because of the aim for freedom with very low involvement of the State in people's personal lives and the economy. How is it that the American way of life is such a strong narrative that so many US people are willing to accept the aforementioned circumstances, although so many inequalities are created?"

0:27:14.3 SC: To the actual question you are asking Kathy, I don't know. I don't know how it is that so many people are willing to accept this. So the question being begged here is, could we change the US system without too much trouble in ways that would be much more equitable to people in terms of healthcare, childcare, university education, etcetera? It seems like the answer to that is obviously, yes. The idea that your health insurance is tied to your employment status is just bizarre. And it is a big part of why the United States has similar healthcare outcomes to other developed countries, but spends twice as much money per person as other developed countries do 'cause we just have a wildly inefficient system.

0:28:08.3 SC: And also I think, although this is a tougher sell, I do think that it's wildly unfair that the education you get is so dependent on the income of your parents, where you were born, things like that. It would be very, very hard to justify any of that from a well-balanced moral perspective. I mean, you're a baby and you're gonna start going to school some day, but why should you get wildly different educational circumstances depending on who your parents are? It's kind of hard to come up with a justification for that. And so I don't think it would be very hard to change, but it would... So it's very easy to imagine changes, let's put it that way, that would make things better. Not perfect. There's always imperfections in the system, but there's obvious room for improvement, but there's also huge amounts of resistance to improvement in that way. And some of it is a little bit sensible, because I do think that when it comes to public policy, one should be conservative in the old school, lower case C sense that if we have a system that works pretty well, there is sort of a reluctance to change it dramatically because we know our system works pretty well, maybe the new system will work better, but maybe it will have unintended consequences we don't know about.

0:29:29.8 SC: So I think a tie goes to the present system in those kinds of circumstances. But like I said, I don't think that this is a very difficult change to make. So I don't think that's the reason why people are reluctant to make it. I do think that part of exactly what you said, there's sort of a resistance to let the government control too much of the flow of money through the country's economy, anyone who knows anything about the actual economy knows that an enormous amount of money in the United States flows through the government one way or the other already, so that doesn't seem like a very legitimate worry to me.

0:30:07.1 SC: I think that ultimately it's a sort of psychological/political problem or state of affairs, let's put it in that more value neutral term, there's a certain image that people have that may or may not be accurate of what government is and what government's supposed to do. There are other images that people have about what it means to be fair and what it means to be just. And like I said, we don't always think these things through very logically, we don't spend a lot of time educating ourselves about them. But I don't know why it's so different in the United States than in other developed countries.

0:30:41.8 SC: Other developed countries have their own problems, of course, and the United States has its own good things about it. The higher education in the United States, even though it's super duper expensive, and that's gonna be a crisis. The research structures that it supports are the best in the world by a pretty large margin, and I don't think that's because our healthcare system is so screwed up, but I'm just saying that I'm not here just to bash the US up and down, I do think that there's some specific ways in which you could obviously better, and I'm not completely sure why everyone doesn't agree with me about that.

0:31:17.2 SC: The Winning Ticket says, "If I understand correctly, Einstein learned about Riemannian geometry from a friend while was looking for mathematics to aid his general relativity quest. Is this a common practice? I.e a physicist has an idea and seeks out mathematical friends, colleagues or literature for unfamiliar maths to interrogate their idea further. Could you conceive of a time when you may be writing out ideas for a paper where an AI program could suggest relevant mathematical theories?"

0:31:45.4 SC: So I think that you sneaked in two questions there, but that's okay, 'cause they're very related and good questions. Yes, it is a completely common thing to seek out help with math problems. Literally, as I'm recording this, I gave a colloquium, my first physics colloquium at Johns Hopkins, at my new university, and I mentioned to them that in some of our work on emergent space time, we needed to use something called the radon transform. The radon transform is a mathematical technique that is actually closely related to what you do in a CAT scan. When you're looking for an image of your brain, you basically integrate along some slice, you don't literally slice it, but along some plane passing through your brain, and if you use that for many, many different planes, you can reconstruct the whole three-dimensional image.

0:32:29.5 SC: We do a similar thing for space time. I didn't know anything about radon transforms when we started doing this. So yeah, we had to look it up, we had to figure out how to do it. It's great when you can just ask a colleague about it, usually you're gonna start with Wikipedia or Quora or something like that, or maybe if you're lucky enough, you have the right textbook on your shelves.

0:32:50.8 SC: Can we imagine a day when it's AI? Sure, absolutely. I think that for the conceivable future, I would imagine treating AI in a way that is very similar to how I treat Wikipedia, namely it's not the definitive answer. I wouldn't trust it. I use Wikipedia all the time, and sometimes non-academics are sort of shocked. Like, "Why do professors use Wikipedia, it's so unreliable." Well, you don't rely on it. That's the answer. You use it to find a pointer to somewhere else, or if you just see a formula that you can re-derive for yourself, that's fine. I think AI is exactly the same way in its current incarnations, I would not trust it to do a calculation, but if it laid out a calculation, I could certainly check it. So I'm very... I do think that AI is capable of doing things like that, that will change how theoretical, and experimental for that matter, physics gets done in ways that are interesting and hard to predict.

0:33:51.6 SC: Herb Berkowitz says, "When the term "spin" is used in relation to an elementary particle, does it mean spin in the same sense as a planet or a baseball. Does the particle turn on an axis or create centrifugal force?"

0:34:04.8 SC: So this is a subtle question, it is spin. You will read in textbooks on quantum field theory, etcetera, that the spin of an elementary particle is not really anything spinning, but I don't think that's quite right. And my former collaborator, Charles Sebens, who is at Caltech in the Philosophy Department has done a lot of work on the quantum field theory of spin in exactly this context. The reason why they say it, it's not a thing they just made it up and were wrong, it's kind of implicit in the way that you ask the question, does the particle turn on an axis.

0:34:37.3 SC: The reality is, there's no particles. Particles are a convenient way of talking about certain things that we observe when we measure quantum fields in the right way, so the reason why in textbooks they'll say it's not really a little spinning particle is 'cause it's not really a little spinning particle, but it is a field with angular momentum. Fields can have angular momentum, and that's why the angular momentum that is contained in what we call particle spin, is part of the overall conserved angular momentum for a larger system. So it's not that there's a little dot or a little baseball that is spinning, it's the field that has angular momentum, and then when you quantize it and look at it, it's a certain quantum amount, that is what we think of as elementary particle spin.

0:35:21.8 SC: Okay, two questions, grouping together, Dom says, "Noether's Theorem says time symmetry leads to conservation of energy, however, in general relativity energy is not conserved. Is that therefore the case that general relativity is necessarily time asymmetric?" And Jim Watson says, "There are various conserved quantities, energy, momentum, angular momentum, charge etcetera, and it is explained that these quantities aren't really conserved under certain conditions or properties of the universe, e.g., in an expanding universe, conservation of energy doesn't hold, what would be the properties or conditions of the universe of the conservation of momentum, or the conservation of charge or other conserved quantities didn't hold?"

0:36:02.0 SC: So these are tricky questions, but good ones. The energy one is the easiest one to explain. So it's not that general relativity is necessarily time asymmetric, it's that the specific solution to the equations of general relativity corresponding to our real world in cosmology is time asymmetric. It's an expanding universe, things used to be closer together and denser, things will in the future be further apart and lower density, that's the time asymmetry that leads to energy not being conserved. In general relativity, if the background... If the spacetime metric is completely stationary, as we say, that is to say if it's completely the same from moment to moment, then energy would be conserved, but that's not true in the expanding universe.

0:36:48.0 SC: For Jim's question about angular momentum and charge and things like that, you can always find places where you have violated this symmetry. That's pretty easy to do. This is the whole subject, roughly speaking of spontaneous symmetry breaking. People will argue over what exactly the definition of spontaneous symmetry breaking is, but let's put it this way, the Higgs field, which has a non-zero value in empty space and therefore breaks the symmetry of the Electroweak theory leads to a non-conservation of charge of the electroweak part of the charge, essentially because that background field can absorb the charge or change it in some ways, depending on what interactions are going on within it.

0:37:30.0 SC: Likewise with the expanding universe, we say energy is not conserved, but it's not that all hell has broken loose, there is a very definite equation sometimes called The Equation, The Covariant equation for conservation of energy, which relates what spacetime is doing to what the energy is doing. So if spacetime is stationary, energy is conserved, if spacetime is not stationary, you can say exactly what the energy is doing, you can say exactly how it changes.

0:37:57.5 SC: Likewise for these other things, for conservation of momentum, for example, conservation of momentum comes from the fact that the universe is spatially translationally invariant. It's the same from place to place. So if you live on a hill... That is not true. If you live on a hill, then there's a direction going down, a direction going up, and guess what, if you put a ball in the hill, its momentum will not be conserved.

0:38:23.2 SC: Now, there's a whole momentum that is conserved for the ball and the earth that it's on etcetera. And indeed, that's because that whole thing is embedded in the situation where there is no gradient in the space and everything is spatially translationally invariant. But if you just zoom in on the ball on the hill, its momentum is not conserved because it's in an environment where spatial translations are not a symmetry.

0:38:46.3 S2: Michael says, "You mentioned in a previous AMA that among your idea of what makes someone an intellectual is someone who is in pursuit of trying to find truth, pointing out that politicians may be intelligent but not intellectual, since as politicians they're not trying to figure out what is true, and so forth. I'm wondering if living in search of truth is what makes someone an intellectual. Does that mean QAnon conspiracy theorists or intellectuals, since it seems that as erroneous as they are, they seem to believe they're in some sort of pursuit of the truth, uncovering what is really true, etcetera. Or is it more the case that using the scientific method in the search for what is true is, what makes someone an intellectual?

0:39:22.4 SC: I think this is a good/fair question because I think I was a little too simplistic when I talked about what makes someone an intellectual for exactly the point, the reasons that you are indicating here. But also I think that defining words can be a little bit tedious, so it's not that there is some correct notion out there that is called, what it means to be an intellectual, and it is our job as scientists to find it, we are defining the word to be what we want it to be.

0:39:52.2 SC: So I think for things like this, there's two ways to go. One is; you can try to restrict your definition of intellectual to someone who finds truth using certain techniques or methodologies, for example, you would want them to be fallibilistic, you would want them to be capable of understanding when they've made a mistake and therefore fixing the mistake, you might demand that as part of your definition of what it means to be intellectual, not necessarily the scientific method, we would want logicians and mathematicians to be intellectuals even though they don't use the scientific method, but you do wanna be able to understand that you've made a mistake. And maybe even more importantly, but less obviously or less quantifiably. To me, what would be important is that you are, I wanna say, sincere in your search for truth, so it's true that conspiracy theorists think they have the truth, but they're not especially open-minded about looking for reasons to change their minds. They're not especially careful or thorough or honest in trying to make sure that their worldview is holding together the right way.

0:41:06.2 SC: So I do think that's a crucially important part of being an intellectual, understanding that we don't have the final answers, that if new data comes in and we have to change our minds, things like that. On the other hand, it would be perfectly okay with me if you just said, "Sure. They are intellectuals. They're just not very good at it." [chuckle] I think we can agree. They're not very good at it, and I don't really think that it makes much of a difference, which of those two directions we go for our definition.

0:41:36.0 SC: Back in the early days of the blogosphere, in the early 2000s, when there was a lot of debate in the science blogosphere about creationism versus natural selection in evolution, and a very common move that is still made today was to say the creationists aren't science because it's not falsifiable, or because they are not naturalistic or whatever... I always thought that was a mistake. I was perfectly happy to say that they're doing science, they're just doing it badly. [chuckle] They have a hypothesis, it's just obviously refuted by the data. I think that it's okay to admit that a lot of people wanna sort of win a battle by making sure the rules are delineated very, very carefully so that their opponent is not fair, is not included in the game.

0:42:24.8 SC: Sometimes you just gotta play the game, you just gotta say the QAnon person. "Yeah, okay. You're searching for truth, but, "Are you bad at it." You done a terrible job." And if you're upset that there is no arbiter of truth, no court of final deciding for what is true and what is not true, welcome to reality. That's just how things are. We have to be able to accept the fact that those of us who do work in good faith and understand that we can make mistakes are gonna have to do our best in the face of other people who think they have all the answers figured out and are not gonna change their minds about it. I've told this story before, maybe even recently, I hate it when I re-tell stories.

0:43:06.3 SC: But when you talk on the podcast for a long time, you're gonna end up re-telling the stories, but there is a famous story of a woman who was a New Age spiritualist, and she would talk to her friends who are sciency or whatever, or skeptics, and she would explain, but then what she eventually sort of converted or de-converted, whatever way you wanna put it, she went to being a complete skeptic from being a new age person. And the thing that was the crystallizing moment for her was when she would ask certain kinds of questions, deep questions about why is there a universe at all, what happened at the beginning or whatever.

0:43:43.3 SC: There are some questions, that wasn't that hard to formulate for which the scientists or the skeptics would say, "I don't know." And her New Age friends would always have an answer, and they thought they could answer every single possible question. If you think you can answer every single possible question, that's not a sign, you're super smart, that's a sign you might have gone wrong somewhere. That's a sign that you might be over-simplifying things a wee bit. And I think that's an important tool to use to remember as we try to do our best, all of us to get more truth in our lives.

0:44:14.9 SC: Anthony Rubo says, "In the last AMA, you expressed disinterest in the explanatory differences between your notion of many worlds and that of David Deutsch's, you are really just content with everyone agreeing on the math. It was a bit startling, it felt like in something deeply hidden, you were championing human-friendly explanations and analogs and did so in several instances, has the zeal for uncovering greater descriptive methods around many worlds truly waned, was it just an off day, or have I mischaracterized?"

0:44:44.0 SC: Well, it could be my fault for expressing things badly, but I think at the end of the day, you have mischaracterized, what I was trying to say. I'm certainly never just content with everyone agreeing on the math. But I think that when it comes to physics in many ways or science more broadly, there are some ways of talking about the underlying system that are either right or wrong, and there are some that are optional.

0:45:09.3 SC: So a classic example that everyone is gonna agree on, I can talk about the box of gas as a fluid with a temperature and a pressure and a density, or I can talk about it as a collection of molecules with positions and momenta. Two different ways of talking about the same thing. That's the kind of distinction that is between how we divide up the world in many worlds. In many worlds, the common thing that everyone agrees on is, there is a wave function, a quantum state of the universe, and that quantum state evolves always and entirely by obeying the Schrödinger equation.

0:45:42.8 SC: That's the theory. That's what you have to agree on if you believe in many worlds. You notice that many worlds never appeared in that characterization, that's because how we take the quantum state of the universe and divide it up into worlds is a human convenience, it is a human convenience in exactly the same way that talking about the box of gas as a fluid or a gas with a temperature and a density is a human convenience, we don't have to do it.

0:46:14.3 SC: There's not even as comprehensive and detailed description as talking about all the individual molecules, but it is still true, it's a higher level emergent description. And there's a reason why David Wallace, who is the leading many worlds guy, former podcast guest, his book on everybody in quantum mechanics is called The Emergent Multiverse, because that multiverse description that dividing the wave function into branches is an emergent thing. And in that case, the whole thing about emerging phenomena is they provide a true handle on what is going on, but at a approximate level, at a way that you ignore some information or don't need to know all the information and can still get some truth about what is going on.

0:47:03.5 SC: But because it's approximate, different people might actually disagree about the best way to divide it up, and I think that David Deutsch and I disagree about the best way to divide up the wave function of the universe, in cases before decoherence has happened. I don't think it has anything to do with ignoring the fact that there's descriptions or just saying it should be just math or anything like that, it's just a matter of where you decide what kind of higher-level description you find most convenient for your point of view.

0:47:33.8 SC: Zach McKinney says, "In your conversation with Will MacAskill, you two discussed how the plurality and evolution of values is essential to the survival and future well-being of humanity. What would you hypothesize to be the core values that enable human societies to survive and thrive in increasingly hazardous times? How might you approach the problem of quantifying and modeling the spread of ideas and evolution of values at different scales within and across cultures?"

0:48:00.8 SC: So I don't wanna disappoint you here Zach, but these are way more ambitious questions that I could possibly answer maybe in my lifetime, much less in this AMA. The core values that enable human societies to survive and thrive and quantifying and modeling, the spread of ideas and evolution of values. Great things to think about. My thoughts on those are going to be exactly as valuable as anyone else who's sort of not thought about them very deeply, but a little bit. So I have no deep Special expert level insights here. I do kind of pause a little bit at the idea of the core values that enable human societies to survive and thrive. I'm not sure there are such things. There are values that I think are good. Values are things that are hard to make lists of because they're not sort of discrete units, a lot of the values, like if you say justice is a value and fairness is a value, there's a lot of overlap between justice and fairness.

0:49:02.0 SC: John Rawls famously tried to portray what we mean by justice as a version of fairness, but other people portray it differently. But anyway, there's a lot of overlap. So I don't think that you're ever gonna find the list of the core values. Having said that, I think that we kind of mostly know, or at least... Maybe not. I always wonder about this because I worry that I'm stuck in some kind of bubble where I think that the people who I talk to mostly agree about these things, but if you go throughout history, whether you're secular or religious thinkers, and you wanna think about human values. Different systems of values often disagree about this or that thing as is very evident out there in the world, but there's other things you see over and over again, right. Some version of the golden rule, "Treat people as ends not means. Do unto others as you would have them do unto yourself. Act in such a way so that your actions would be part of a universal Maxim, whatever you wanna call it. Different ideas of treating other people with dignity.

0:50:05.9 SC: I think that's a core human value. As a human value that gets in the way sometimes of a simplistic utilitarian notion of greatest good for the greatest number, because sometimes maybe you can convince yourself that you can get a great good by under-valuing the dignity of somebody, and that's why it's hard to write down the fundamentalist values, 'cause I think the greatest good is also a pretty good value, let's try to get as much good as we can. I think that at a detailed person-to-person level, the idea of treating other people, not necessarily as you would like to be treated, I think it's a little bit simplistic 'cause other people might be different than you. That's why Kant when he was formulating the categorical imperative was trying be a little bit more sophisticated about it.

0:50:50.9 SC: It's hard to put exactly into words what is going on here, but the basic idea is that there is... We should act as if there is some inherent dignity in other human beings. That sounds right, and you say it and people are gonna nod along. Then you can get into edge cases. What counts as a human being? Does an unborn baby count as a human being, does a chimpanzee count as a human being, does a smart computer count as a human being and... Yeah, that's fun. And we can think about it, but that's why it's not rigorously done.

0:51:24.7 SC: So I think that kind of... And that also goes back to the podcast conversation I had with Paul Bloom about empathy. I think that at a more practical level, not just sort of an airy fairy, what are the values kind of level, but at a down in the grit, what actions do we take kind of level. Paul wanted to argue that rationality is sort of a better guide to doing good things than empathy is. And his argument, which psychologically makes sense, is that people are just much better at empathizing with people who are like themselves, whereas if we are rational and Universalist, we can say in a more clear cut focused way, that we should be good to everybody in the world, not just people like ourselves. But I think that, again, at the actual implementation level, there's a huge failure mode for that kind of thinking, which is that it's really easy to think you're being rational when you're not... That's not to say we shouldn't try to be rational, but I think that we cannot pay attention to everything in the world.

0:52:31.7 SC: We're gonna take in certain information, we're gonna ignore other information, and we might very well be being rational on the basis of the information we're paying attention to but that's falling short of being perfectly rational. And that's why I think the empathy is important because one way of opening our eyes to other kinds of information and concerns and considerations that we might not otherwise take seriously, is to imagine putting ourselves in the shoes of other people.

0:53:00.2 SC: So one way or another, that kind of idea, however you wanna parse it, is what I think should be the core value of human societies, taking other people seriously, thinking about their needs, what if I were in their shoes? There's no simple way of putting it, but something along those lines. As far as quantifying and modeling sort of ideas and evolution of values, I have no idea how to do that, that's something that... I'm not even sure if that's a well-posed question, maybe if we could hack it down into some well-posed questions, we could make some progress on it.

0:53:33.5 SC: Okay, I'm gonna group two questions together. James Maddix says, "At the end of the podcast with Antonio Padia, you were discussing if the universe is finite or infinite, as someone who agreed with your arguments on the naturalness of infinity, I was shaken by his rebuttal of... Well, which infinity then? Is there any lifeline you can throw to those of us disturbed by the prospect of living in a finite universe. And then Eric Chen says, "What's your own take on the last question you asked Tony Padia, is reality finite or infinite? What are the best reasons for taking either view on this question?"

0:54:06.2 SC: So I think Eric's question is very straightforward, and I'll take a stab at answering it. James's question is sort of frozen, the interesting personal feeling kind of aspect to it, being disturbed by the prospect of living in a finite universe. So my real advice would be don't be disturbed by anything like that. You're asking for trouble, if you're, in some sense, hooking your own sense of well-being to any large scale features of the universe as a whole, 'cause we don't know what they are. The Universe could be finite, it could be infinite. We just don't know. So don't be disturbed one way or the other, that I would say very strongly.

0:54:43.6 SC: So as to whether it's finite or infinite. I'm actually open-minded about this. I'm more open-minded than I used to be. I used to think it was just infinite. For basically arrow of time type questions I think that if the universe lasts forever then it better have an infinite number of things it can possibly do, because otherwise we'll just do some subset of things over and over and over again. If there's only a finite number of states that universe can be in and infinite amount of time you're gonna be repeating yourself an awful lot, and that gets into various problems that are essentially variations on the theme of Boltzmann brains one way or the other. So a universe that has an infinite number of possibilities and the last forever in time is one way out of that, and that's sort of the idea that I put forward with Jennifer Chen back in the 2004 paper. But there is another thing that you can say that is completely legit on the table if the universe is finite in both the number of states, it can take on and in time. So if the universe has a boundary in time or a cyclic in time or something like that, then in principle, we could imagine a well-posed arrow of time within that finite period of time.

0:55:58.8 SC: I just don't know how to make that work. I don't even have a suggestion as to how that might work, but it's completely possible, I do have a half-written paper that I should finish writing some day on a completely finite, discrete version of quantum mechanics, which is both a little bit harder to make than you think and still possible. Still not that hard. So I think it's worth pointing out there. But it's not because I think the universe is like that, it's just because it's important to keep open all the possibilities as to what we should be contemplating, when we ask these big questions. I'm in favor of asking the questions, I just don't have strong feelings about what the answers are.

0:56:37.5 SC: Derek Bain says, "I'm really enjoying the new book, and for what it's worth, I think it exceeds in making physics accessible to a total novice like myself. Thank you, Derek. Now the question, "Have you dressed up for Halloween in the past? And if so, which of your costumes are you most proud of?"

0:56:56.4 SC: Yeah, I like the buttering up approach to asking the question gets me to more likely to answer it, I'm happy to do that. And I haven't dressed up for Halloween in a while, to be honest. It is not one of the holidays that I do anything special for, usually. When I was a kid, of course, yeah, we'd go trick or treating dress up for Halloween. Probably the best costume was one that we made to look like a robot, so I had a big cardboard box, spray-painted it silver, and every electronic gizmo and gadget that we had in the garage was temporarily attached to the box, so I don't know, and amp metre, something like that at various bells and whistles, there wasn't a lot of stuff. We weren't a very highly technologically advanced household when I was a youngster. But we did our best, and I thought that was at least a time when I showed some creativity there usually store-bought costumes were perfectly fine for me.

0:57:53.0 SC: Gotta group two questions together here, one is from Ken Wolf who says, "Presuming such things exist, if we found there was a primordial black hole near enough to send an orbiter, what experiment would you most like to see done, and what question would you be hoping to answer?" And Rew Phillips says, "If a black hole were able to come close enough to our solar system that we can send spacecraft out to it in our lifetime. What questions would you want to try and answer that we aren't able to get at easily with black holes, too far to reach with a spacecraft?"

0:58:24.2 SC: Well, black holes are actually not... Actually probably that mysterious in terms of how they behave. Again, it goes to the fact that our current understanding of the laws of physics seems to be pretty good. So if you have a medium-sized black hole, good old Einstein's classical general relativity should be super good at explaining what it is like. We should have already a pretty good picture, there's not like mysteries of black holes that we need to observe them to figure out.

0:58:58.8 SC: Of course. The theory could be wrong. General relativity could be wrong. So there could be deviations from real black holes to what is predicted by general relativity. So far, we haven't seen that. The best chance to have seen that so far was in the LIGO detection and gravitational waves. It's a little bit crude 'cause you're only seeing a tiny little bit of the last part of the in-spiral to black holes, but still, you can try very hard, and they do try very hard to match the predictions of General relativity to precisely the kind of gravitational waves that they observe, and the answer is it's smack on. It's exactly right. So it would be enormously exciting to find out that the gravitational field of a black hole was somehow not quite what was predicted by General relativity. But that's... I wouldn't bet on it if I were there.

0:59:53.3 S2: Now, if it's a tiny black hole, then we have a chance of seeing Hawking radiation. The thing about Hawking radiation is that the temperature at which the black hole is emitting is higher when the black hole is smaller. So if it's a big black hole, it'll be essentially invisible as far as Hawking radiation is concerned. If it's a smaller black hole, there will be a point, depending on what your instrumental sensitivity is, where you can actually observe the hawking radiation. You don't wanna observe it being too hot 'cause that means it's about to explode and you don't wanna get too close by. But certainly observing Hawking radiation would be fascinating. Again, there's a very good chance that it will just look like what the theory predicts. We have a theory, Hawking wrote down the theory that predicts it.

1:00:38.3 SC: So it would be enormously interesting and well, revolutionary if we saw either no Hawking radiation where we should or we saw Hawking radiation, but it was a different kind of thing than we expected, any one of those would be super, super interesting. So the two big questions, I wanna know the answer to that we could test if we were near a black hole are, what is the gravitational field and what does the Hawking radiation look like? We have very good predictions for what they should be, but any deviations from those predictions would be very, very, very important.

1:01:09.7 SC: Robert Ruxton Drescue says, "I had a bunch of scientific questions on my mind, and I'm going to change the topic and ask something else, something that is important for me, bullying. When I was little, I was bullied a lot. Both in elementary school and in high school. The main reason that I was considered the school's nerd, have you personally had to deal with bullying, if so, what did you do and what was the reason?"

1:01:31.3 SC: I guess I experienced a little bit. I was a pretty nerdy kid as a youngster also, but I mostly managed to stay away from it, maybe because there were other kids who are even more fun targets to pick on than I was. I was picking on a bull, but not very fun to pick on I didn't respond in the way that they were hoping, maybe. But I don't know, maybe I'm just misremembering or maybe there were other things going on. I went to a big public high school, there are plenty of kids to be picked on. I do think it's bad. I mean, I don't think that there's a strong pro-bullying lobby out there, so it's not something that should be very controversial. I presume, I guess that there are probably people who think that maybe it toughens you up. Certainly, there are kids who are pro-bullying 'cause they are bullies, but Jennifer, my wife always points out the scientific study that was done about bullying, but it was a weird kind of study where they took kids and they had some independent way of judging who were the popular ones, who were the bullies, who were the nerds, who were picked on who were the outcasts, whatever.

1:02:37.1 SC: And they had them watch the Disney movie Dumbo. And you know Dumbo is an outcast, Dumbo is picked on by everybody else until he learns to fly and then he's a star... Right. But early on, he's bullied. That's exactly what happens to Dumbo. And so they asked the kids, some of whom were super socially popular and some were bullies and others of whom were outcasts or whatever, they said, Who do you identify with in this movie, and the answer is, everyone thinks they're Dumbo. Everyone thinks that they're the ones at the end of the day who are picked on, even the ones who you might have thought were picking on you. They thought that someone else, maybe it was a teacher, maybe it was bigger kids, maybe it was someone at home, someone was picking on them, so I don't think anyone would stand up very much in front of or In favor of bullying.

1:03:27.5 SC: So the question is, what to do about it? And there, I don't have any great suggestions, I do think that maybe one tiny suggestion is just acknowledging the problem, to be sensitive to the fact that things that happen to people when they're very young can affect how they turn out when they grow older, and not just imagine that kids should toughed it out and put up with misbehavior on the part of their peers or whatever. To be a little bit more sensitive to how kids treat each other. Kids can be super duper kind and generous, and they can also be super-duper nasty and selfish. They haven't learned, they haven't always learned to separate one from the other and learn that it's okay to be generous and that it's not okay to be a bully and whatever, and I think that these are things that we should be teaching our kids.

1:04:18.3 SC: And there are some teachers who are super-duper good and are able to do that, and there are other teachers who don't have that training or don't have that empathy or that ability or whatever. There are other teachers who are bullies, and we probably have all had them along the way. So maybe the simple thing to do is just to remind ourselves that we don't do a great job in valuing the job that is done by teachers, whether it's in terms of social respect or how much they get paid, or the education we give them, it's not necessarily considered a high status occupation in our society, so if we had teachers who are better equipped, and not only the training but also just class sizes, resources, things like that, then maybe they'd be better able to make sure things like that doesn't happen in their schools but, I don't know, I'm not an expert there. I have not spent a lot of time recently in my life in secondary schools or anything like that, or elementary schools.

1:05:18.9 SC: Sheldon Sillyman says, "I'm guessing you might consider evolution as an emerging phenomenon, and if so would you then say this emergent implies a strong possibility that evolution would operate throughout the universe. Is emergence universal, and how does that work for such fuzzy concepts like culture and agency?"

1:05:36.7 SC: So I absolutely think that evolution could be universal. Evolution is a little bit misunderstood sometimes, there's always a stage in a young scientific kid's life where they hit upon the idea that evolution is basically tautological. Survival of the fittest. Well, who else is gonna survive. You're gonna define the fittest as the ones who survive and they're gonna pass down their genes, and that's how it's gonna work.

1:06:00.9 SC: The reality is more subtle than that. The reality of biological evolution is specifically that there is random variation, tiny random variation in mature species, but there's random variations from generation to generation. So in some sense, the genome is doing a search through parameter space, it's a very inefficient search in a whole bunch of ways, but that's 'cause it was not designed to be efficient. It was what is naturally happens in some sense, so it doesn't count as evolution if you simply have progeny, it only counts as evolution, if you have some information in one generation that is passed on with the possibility of slight variations to the next generation. But that's not that hard to imagine happening. If you have any life form that is based on genetic information, it's never gonna be passed on 100% perfectly all the time, so I think it would be very natural for evolution to happen on other planets, other places, other biospheres or whatever.

1:07:01.3 SC: And yes, it's an emergent phenomenon, but in the very weak sense, it's not fundamental. It's real, but it's not fundamental. Things that are real but are not part of our most comprehensive description to physical reality are emergent, whether it's tables and chairs, pressure and temperature, evolution and culture, all of those things are higher level and therefore emergent, as long as you believe the world is fundamentally physical, which I do.

1:07:28.8 SC: Michael Monhopt says, "Which individual steps are happening when two particles become entangled or disentangled, and how long is this process from not entangled to entangled approximately take? Oops, I'm gonna combine this together with the next question, which is from J. Peters a priority question. Remember, everyone gets one priority question to ask in their lifetime, and I will do my best to answer it. "What is the nature of the interaction among particles that are said to give rise to quantum entanglement? Is it just a matter of spatial proximity, such that the closer together they are, the greater the level of entanglement, or does it have to be some sort of event that includes both and that establishes their entanglement?"

1:08:08.7 SC: Well, there is a difference between an interaction as such, and then interaction that causes entanglement, some interactions do not close entanglement. Basically, what you have to imagine is that at least one of the quantum mechanical systems is in a superposition, and I'm slowing down here 'cause there's technicalities here that I don't wanna get into, every system is in a superposition in some vague sense, but if I can just get away with saying, "You know what I mean?" If you have like a spinning particle along one axis and its spin up plus spin down that it's in a superposition, or if I have a particle with a superposition of being in this position and also in some other position over there, that's what I mean by a system in a superposition. And then entanglement happens when that system interacts with some other system in such a way that the different parts of the superposition interacts differently.

1:09:09.2 SC: So the example I usually use is, if I have a spinning particle spin up and spin down, some superposition of spin up and spin down, and I drop the particle, then it is interacting with the Earth because it is interacting with the gravitational field of the Earth, but it does not become entangled with the earth because both the spin-up and the spin-down parts of the superposition evolve in the gravitational field in the same way to extraordinarily good approximation. So there's an interaction, but it's the same interaction for all the different parts of the superimposed quantum system, so there's no entanglement going on.

1:09:46.9 SC: Whereas if you have something like shortages capped, the superposition is between an awake cat and asleep cat, and they are in two different locations. The awake cat is up and walking around, the asleep cat is lying on the ground, sleeping, and a photon can very easily be absorbed, let's say, by the awake cat and completely non-interacting with the asleep cat. So that's an example where the particle interacts, the photon interacts differently with the awake part of the cat and the asleep part of the cat, and therefore they will become entangled. So that's what you need to become entangled when one quantum system interacts with another quantum system in superposition differently with the different parts of the superposition. So spinning particles do this all the time, there can be interactions, there are generally interactions between particles that depend on the spin, so if you have one particle simply passing by another one, two neutrons, for example, let's say, and they're in a superposition of different spin states, the up-spin parts of the neutrons will interact with each other differently than the down spin parts, and something like that for electrons rather than neutrons is very often what is used in designs for quantum computers or something like that.

1:11:10.0 SC: Another way to do it is to create particles that are entangled from the start, so when the Higgs boson decays, the Higgs boson has zero spin, so when it decays into two spinning particles, those two spinning particles have to be spinning in opposite directions, so that angular momentum is conserved. So we don't necessarily know which direction either one of them is spinning in, but we know it's entangled with the other particle that the Higgs is decaying into, because the two different parts of the superposition are connected to each other in the way that we identify as entanglement.

1:11:44.9 SC: So Cooper says, "When you talk about other universes with different laws of physics, do you just mean their fundamental constants have different values, do you mean completely different underlying equations, like different terms in GR or different gauge symmetries in QFT?"

1:12:00.1 SC: Well, that depends on the context and what you're talking about, universes with different laws of physics. Specifically in the context of something like the String Theory landscape. So the String Theory landscape comes about because we think there are extra dimensions of space in string theory. They can be curled up and hidden from our view in various ways in a large number of different ways, and those ways all give rise to different low-energy laws of physics, different local visible laws of physics. And in that sense, this is the basic laws of quantum field theory, Relativity, etcetera, are still 100% the same from universe to universe, but the set of particles can be different. We have quarks and leptons and Higgs in our universe, so maybe they only have leptons or don't have anything that you would recognize as quarks or leptons, or maybe you only have spend zero particles or whatever. There's a whole bunch of different possibilities.

1:12:55.1 SC: Even if you had the same particles, you gonna have different interactions between them, either different actual forces, so different gauge symmetries or different strengths of forces, different values of the cosmological constant, you can even have different numbers of dimensions of space. Okay, you can have some regions have six-dimensional space, some have three-dimensional space, etcetera. But still all under the general rubric of Quantum Field Theory and Relativity, because the underlying theory is String theory, which has in the low energy limit Quantum Field Theory and Relativity as part of its description of physics. Now, if you are not thinking of the String theory landscape, if you are thinking more generally... I can imagine all sorts of things.

1:13:35.3 SC: I don't necessarily have a physical mechanism for making them, so whenever I talk about the Multiverse, I try to emphasize the fact that it's not just saying there's a whole bunch of universes out there. There are physical mechanisms that can bring these different universes into existence. In cosmology, we have eternal inflation, and we have String Theory, and these arguably, anyway, give rise to a Multiverse with different laws of physics in different places. And so in that case, they would still be under the Quantum Field Theory rubric, but with very different particles, forces, etcetera.

1:14:10.8 SC: Anonymous, says, "The Standard Model is called the most successful theory ever. Well, isn't it like the most successfully tuned theory ever? Every time a result comes in, some parameters are tuned to produce that value and ranges for other parameters may further be constrained. No wonder the standard model agrees with experiment."

1:14:26.6 SC: So I don't know where you have been picking up your physics anonymous, but that is completely not true. It is very, very much not the case that every time a result comes in, some parameters are tuned to produce that value. The number of parameters, the number of experiments I should say, that are done on Standard Model particles is enormously larger than the number of parameters that we have, in the theory, it is highly, highly, highly constrained because we want to find a mistake in it, we want to find that it somehow deviates from the predictions that we make. For example, for the Higgs boson, we discovered the Higgs boson, mostly looking at it decaying into two photons, and that basically fixed the one undetermined parameter of the model namely the mass of the Higgs.

1:15:13.8 SC: And then we said, "Okay, now we know what the mass of the Higgs is." And then once you know that, you know the rate of decay of the Higgs boson into electrons and into top quarks, and into W bosons and all of those things, there's no extra free parameters, those are all predictable in terms of the known parameters. And then we go out and test them, that's what people at the LHC actually do. So it is quite a bit of wonder that the standard model agrees with the experiment. It is highly highly over-constrained and remarkably resilient at agreeing with the experiment.

1:15:45.3 SC: Keith says, "I happened to see the 76ers are playing the Wizards tonight in your neck of the woods as they say. Any particular fun in-person, 76ers game memories you feel like sharing as a kid or whenever?"

1:15:56.0 SC: I gotta tell you, Keith, the 6ers are not doing well to start the year, and I had very high hopes for them and continue to have very high hopes, 'cause I'm generally an optimistic sports fan, despite originating from the Philadelphia area. So I hope they get their act together. But right now, I have to say, I have different ways, for example, of going online and reading things and reading Twitter or whatever, and when things are going well in basketball, and with the 6ers, reading about the 6ers is like my happy place, and I can ignore the rest of the problems the world haves. And then when the 6ers keep losing I'm like Jesus, just no more happy places on the internet. I'm not quite sure what to do about that.

1:16:35.1 SC: When I was a kid, we didn't go very often to the 6ers games, maybe we could go maybe once a year or something like that. And I do remember going to a game, I don't remember what year it was, but it was before they won the championship in 1983, but not too long before so early 80s, watching the 6ers playing the Boston Celtics, their hated rivals, and it was in the Spectrum, the previously existing building, which at the... When it was built in the 60s or 70s or whatever, was a state-of-the-art facility, but by later standards was quite a small little building and the joint was rocking, man, when the 6ers would play the Celtics, it would be sold out, everyone would be shouting, and they were pretty well-informed fans, like Larry Bird on the Celtics would always cheat and not play man-to-man defence and the 6ers fans would start chanting, "Who's bird guarding?" Because there were rules against illegal defence back in those days, and whenever anyone got fouled, which happened a lot back in those days, everyone would jump to their feet and either boo or cheer depending on how it went. And it was really... It was a nice, painless, relatively harm-free way of feeling some common emotional bond with your friends in the fandom of the 6ers.

1:17:56.1 SC: So, and it is all because not only was basketball fun, but that particular rivalry was so amazing and so emotional and I hope it comes back. I know that Boston did very, very well last year. Hopefully the 6ers, can live up to their end of the bargain one of these days, and then the rivalry will be rejoined with gusto.

1:18:16.5 SC: Andrew J says, "Keeping in line with your thinking about social systems using ideas from physical systems, what role, if any, do you think entropy has to play in macro-societal actions? Is human progress doomed to simply shift disorder to whatever system we have the fewest problems with be it the environment, international trade, etcetera?"

1:18:35.9 SC: Well, I think that you need to be a little bit more careful when we think about these big complicated macro complex systems, when you invoke ideas like entropy. I think there is a place for ideas like entropy, but it's a lot more subtle than mixing cream into coffee, when you mix cream into coffee, entropy goes up, but that statement that entropy is going up is pretty comprehensive. That basically tells you what you need to know. There's not a lot of new nuances along the way. Once you get to biology and psychology and sociology, or even things like weather or plate tectonics, just saying entropy increases doesn't come anywhere close to capturing everything that is going on. But I think that's an interesting part of the problem, not a reason not to think about it.

1:19:24.5 SC: Entropy does go up, but entropy goes up in closed systems, which the usual way that we think of human systems, they're not closed. We interact with the rest of the universe in very important ways. The biosphere on the Earth is dramatically not closed, the entropy of the biosphere is not going up in any obvious way, we get low entropy radiation from the Sun, we give it back to the universe in a high entropy form, so the entropy of the universe is going up, but here on earth, the entropy is pretty low and stays that way. Nevertheless, within some particular system, you can go beyond just saying entropy goes up in closed systems, and you can think about how different degrees of freedom relax and locally increase their entropy while entropy might be going down, or being exchanged or heat is flowing in some way, somewhere else.

1:20:17.5 SC: So I don't think it's simple. I don't think that human progress is doomed to shift disorder around, I think that's way over-simplifying what is actually a very, very complex situation. One way to put it is the time scales for things like... I don't know, biology, all of biology, like the history of human life or the history of the Sun or something like that. The time scales for these large-scale systems we're talking about to come to equilibrium are enormously larger than the lifetime of the human being. So even though there is some overall sense in which entropy is going up, the details of the way in which it goes up matter a lot. And maybe that's room for coming up with new and important principles of physics or of socio-physics or political physics or something like that. I'm not quite sure. Certainly Complex Systems researchers care about problems like that.

1:21:10.5 SC: Okay, Brendon says, "Do you think your deep understanding of math and physics enables you to quickly or easily comprehend other technical fields such as Computer Science, for example, are you able to understand machine learning and or computer programming with little difficulty?"

1:21:27.0 SC: Well, I certainly wouldn't say little difficulty, I can't even understand other areas of physics that I don't already understand with little difficulty, there's always difficulty involved. But also, of course, there is a familiarity with certain ways of manipulating symbols, ways of reasoning or whatever. I think that my ability to pick up something in computer programming is much better now than it would be if I had no physics training, but I was otherwise the same person, but it's very, very far away from saying, little difficulty.

1:21:56.1 SC: Okay, Brian Mapes, says, "Here's some numerology. Is there anything fundamental about 10 beyond four fingers post opposable thumbs being bio-mechanically successful, and even spookier, what is up with 10 to the 10 bits in the genome neurons in the brain? Stars in the galaxy, galaxies in the universe. Enough data for machine learning, etcetera?"

1:22:19.2 SC: Well, no, there's nothing fundamental about that at all, even in biological life forms here on Earth, they don't all have 10 fingers and toes. I've known plenty of cats who don't have 10 fingers and toes, so and in 10 to the 10. Certainly there's no relationship there. For one thing, it's not even true that that's the number of galaxies in the universe, it's closer to 10 to the 12, and if we're starting to ignore differences like 10 to the 12 versus 10 to the 10, you're gonna find a lot of coincidences out there because you are just being quite forgiving, in when you say the numbers are similar to each other, so I wouldn't draw too much conclusions from that little bit of numerology.

1:23:01.7 SC: Henry Jacobs says, "Lottery voting is an election system wherein a single voter is randomly selected and their vote decides the election. Here are some positives. Number one, it's a proportionate representation system. Number two, voters have more power than in a plurality-based system, if you model the voters as biased coins, the mutual information between a voter and the election outcome decays quadratically with population size in plurality systems decay is exponential. And then Henry lists a whole bunch of other positives and he says, "As you can tell I'm a fan of this system, there are issues nonetheless. Do you think this is a good starting point?"

1:23:35.6 SC: So just to say again, for those of you who are not familiar with this, the idea is that rather than letting everyone vote on a candidate or some kind of plebiscite or whatever, to actually pass a ballot resolution or whatever, rather than doing that and just counting the votes and doing the majority, lottery voting says, "Let's pick a random person within the electorate and just let them decide." It is easier, it's cheaper to do that, than to have everyone vote, but otherwise no, I am not a fan of this. So I'll tell you why I am a fan, but, even though I'm very much not a fan of the system, I get it, I'm not super-duper happy with any voting system, and I think that there is a problem. And the basic problem of voting systems before I answer your question, the basic problem of voting systems is, how much should we care about representing minority viewpoints.

1:24:36.2 SC: So let's imagine we have an election between three people, three people are running for President or something like that, and roughly speaking, half the people are very, very happy with one candidate, almost as happy with the second candidate and cannot stand the third candidate. Roughly speaking, the other half of the people are really, really happy with the ones who the other one hate, are almost as happy with the ones the other ones put second and really, really hate the ones the other ones put first. Okay, so in other words, there's one candidate that gets a lot of preference or a lot of hate, there's one candidate who gets, a lot of preference or a lot of hate, and there's a third candidate who everyone would be happy with. Under the current system, that person who everyone would be happy with gets zero votes, because there's another candidate that's better than them.

1:25:27.4 SC: So this is a good reason to say that we might not in our current system, be taking into account all of the preferences that people have, okay. And you can actually... Even though even... There's even rules about... There's principles that people put forward that are supposed to be things we would want to have be true in any given voting system, and you can almost always find a voting system that seems reasonable, that violates some of these rules. So it's a very complex and nuanced kind of thing that I'm learning a lot about in the physics of democracy class. Having said that, the problem with the lottery voting is the following, imagine that you have a system where 90% of the people think one thing, and 10% of the people think something really, really different, like you're voting for a candidate, and there's some 10% crazy, fascist, racist party, and then the other 90% of the people are voting for the regular parties.

1:26:19.8 SC: In the current kind of system or in any ranked choice system or any range voting system. The people, the 10% crazy, racist, fascist would never win, and that's taken to be an advantage of the system because the crazy fringes are not supposed to win, but in a lottery voting system, the crazy fringes would win 10% of the time and 10% things happen a lot. Quite a bit. And so there's actually, it is thought to be something of a virtue of voting systems, if they can sort of smooth out the rough edges and take more or less the average rather than taking a representative sample. So as Henry says, mutual information between a voter and the election outcome decays, quadratically with population size and plurality systems decay is exponential. That's a feature, not a bug. We're not trying to necessarily... Exactly represent the will of the people including the crazy fringe people.

1:27:28.0 SC: Now, you can debate that. That's why I said at the beginning, this is all very debatable. You might make the point of view that, "Sure, there could be a 10% crazy fringe group. But there also could be a 10% like really, really good group and also never gets its voice heard." But I do think that there is something to be said that if you're going to live in a democracy, it's not only that most of the people should get their way, but we should do our best to get a situation where most of the people aren't too dissatisfied.

1:27:57.1 SC: So it should be more than just majority rules, in my view, there should be a way in which people who don't get 100% of what they want are nevertheless not trampled over. And the worry in a lottery voting system like that is when those 10% win, the 90% are gonna be trampled over, and that could be bad. So some smoothing out of the extremes, I think is actually intentional and good in a voting system. Having said that, I don't know what my favourite voting system actually is so, further that and further persuasion is welcome.

1:28:30.9 SC: Dory Vinnet says, "Not a question, but I think you'd like knowing that my cat associates your voice with treats, I often listen to Mindscape while making dinner and now when Bested hears your voice at other times, she runs to the kitchen." [chuckle]

1:28:44.8 SC: So I am very pleased to hear that Dory, and I'm glad that you have a positive association with my voice, Bested. And I hope that you get all the treats because you're a good Kitty who deserves all the treats.

1:28:55.9 SC: Yohan Falk says, "What mathematics do you think everyone should learn in school regardless of career path?"

1:29:03.3 SC: These are some of the questions that I know I don't have strong opinions about because these are hard questions, and I don't think we should be too glib about them. I would like everyone to know basic algebra, trigonometry, geometry, the things that we actually do try to teach to our students. I think you should be able to plot a function. In fact, I think you should be able to know the concepts of a derivative and integral even if you can't do them, and this is part of the idea behind The Biggest Ideas books, is that you shouldn't be able to understand what it means if someone says, "Oh look, the maximum value of this function is where its derivative vanishes." That's not that hard to understand and everyone should understand that. And I think that we do try to teach those basic things.

1:29:49.7 SC: As John Allen Palo said, and I completely agree with, "There are plenty of things in statistics and probability that absolutely should be taught more." Just the idea of probability, the axioms of probability, basic ideas about how to use it, marginal probabilities, conditional probabilities, things like that. Some applications to the real world. It's not that hard to understand Bayes's Theorem, I think that everyone should understand Bayes's Theorem when they come out of high school. So that would be nice. But a lot of things are nice, I don't know what else would have to go to do that, which is why I can't really claim to have a sweeping program for fixing Methane in schools.

1:30:27.9 SC: Michael Kramer, says, "Concerning the Past Hypothesis, the hypothesis that the universe was initially in a state of extremely or maximally low entropy, is there a way that that might be tested experimentally?"

1:30:39.7 SC: So, yes and no is the answer here. We make observations, like we take a map of the Cosmic Microwave Background, from those observations, we infer what the early universe was like, it was hot and dense and very smooth. From that and our knowledge of physics, we can calculate the entropy. And it was very low. So in all that chain of logic, we have made an observation that the early universe had a very low entropy.

1:31:06.5 SC: The problem with that logic and with all logic like that is that it assumes the past hypothesis because we don't actually see the early universe, we see photons landing at our telescope. The connection between the photons landing in our telescope and what the early universe was like, is made on the basis of assuming that entropy has been increasing the whole way, so that's why it was dubbed by David Albert correctly, The Past Hypothesis rather than the past fact, even though we can observe it. But we observe is that it is consistent, it is a self-consistent set of assumptions to imagine the early universe had low entropy that is compatible with what we see. But it's also always possible the universe had high entropy and we just randomly factuated it into existence, and there's no experiment you can do, that can rule out that possibility.

1:32:00.5 SC: Roy Thompson says, priority question. "When black holes merge, how is the mass converted to gravitational waves? Any implication? For the black hole information paradox?"

1:32:08.8 SC: Well, remember, mass is just a form of energy when you talk about the mass of a black hole, you're using E equals MC squared. If there's energy in the black hole and the black hole in its rest frame is stationary and it has a mass, E divided by C-square. So really the question is what is happening to the energy? And there's also energy contained in the orbits of the black holes, black holes are not gonna merge unless they're moving, so there's some kinetic energy also, and it's all in... Contained in the curvature of spacetime, all of that energy... That's the only thing that exists. You don't need any solid material in the black hole, if you had any it would question the singularity, the black hole is a region of spacetime, and outside the black hole is a region of spacetime, and.

1:32:58.3 SC: So all of the energy in the black holes and in the gravitational waves is all contained in the curvature of spacetime. So there's no real conversion from mass of the black hole to gravitational waves, it's one configuration of curve spacetime evolving smoothly according to Einstein's equation into another configuration of curve spacetime where the energy is the same, but now some of it is moving away in the form of gravitational waves. And I don't think this has any implication for the black hole information paradox, because you don't need to talk about black holes merging or gravitational waves to talk about the information paradox.

1:33:37.1 SC: Shlyer says, "You've said that you take the universe to be a closed system, thermodynamically, I know some other physicists don't, though I think they are outliers. Can you describe the status of our knowledge here being unbounded, expanding and maybe infinite, the universe doesn't seem much like a piston chamber?"

1:33:55.5 SC: Well, our knowledge is very minimal here, right, 'cause we're talking about the universe as a whole about which we know very little. Now, I think I'm missing something when you say the universe doesn't seem like much like a piston chamber. That's true, it does not seem much like a piston chamber, a piston chamber is a paradigmatic, not closed system, there is an external thing that pulls or pushes on the piston and the walls of the pistons move in response to that, and therefore the system inside can increase or decrease in heat or entropy or whatever. It is not a closed system by any usual way of thinking.

1:34:31.4 SC: The Universe is usually thought up to be a closed system for two reasons, number one, when you see no reason why it shouldn't, [chuckle] there's no either a theoretical argument or experimental evidence that the universe is not closed. Number two, it's not even clear what it would mean for the universe to not be a closed system, unless you have some weird definition of universe, a closed... A not closed, an open system is one that is exchanging energy and information with another system, so if our universe was exchanging energy information with another system, I would just redefine universe to include that other system too.

1:35:09.4 SC: I don't know what it would be. Again, there's no need for any such system on the basis of theory or experiment, but my usual philosophy about these things is to admit that lots of things are possible in cosmology, etcetera, but to try to keep things as simple and as close to what we already know is true, and work out what would happen in those cases. So I think that just viewing the universe as a closed system is perfectly simple and compatible with everything we know. So I'm gonna go with that.

1:35:37.9 SC: Martha Hendrix says, "What socio-cultural rituals and ceremonies do you or have you ever participated in? I.e were you married by a Religious Efficient? Do you watch fireworks on the Fourth of July? Fast during Ramadan?"

1:35:52.4 SC: Do not fast during Ramadan, do not watch fireworks on the Fourth of July. We were married, I guess, by a Religious Efficient, namely a friend of ours who got one of those online religious order you have $25, you're now a holy man kind of thing. In California, that's all you need to marry somebody, but not really very religious, honestly. But we did have a ceremony, we got married, there was a ceremony. We modified our wedding vows from other wedding vows and the whole thing, and I take that very seriously. I think that's very... I don't wanna say it's important, it's important to me. It may or may not be important to someone else. I think that rituals and ceremonies are very important, but I have no special attachment to other people's favourite rituals and ceremonies. So Jennifer and I would never go out for a romantic dinner on Valentine's day that just seems like asking for trouble. Everyone else is out, and they're all crowding the restaurants or whatever, and we can very easily go out on some other day and have a very nice dinner.

1:37:03.4 SC: Likewise, neither one of us are big fans of the traditional Thanksgiving turkey dinner, but we did replace the traditional Thanksgiving turkey dinner with a ritual of going to Las Vegas every Thanksgiving and having Peking Duck at the restaurant, Jasmine in the Bellagio. That was easier to do when we could drive there from LA. So we're not gonna be doing that this year. We need to establish a new tradition. We have various traditions for Thanksgiving for New Years, for birthdays and things like that. So I think that they're... My personal traditions and rituals and ceremonies are important, but if you're asking about the commonly shared socio-cultural ones, no, I don't have any special attachment to those. Except of course, like sports and things like that, which I'm a big fan of, I think... Again, it's a sort of harmless fun way to get swept up in the crowd and enjoy their enthusiasm together.

1:38:00.3 SC: As I record this, the Philadelphia Phillies are still in the World Series. They may have lost by the time you're listening to it, or they may have won by the time you're listening to it... So the City of Philadelphia will be very, very happy. I'm not a huge baseball fan, so I'll be mildly happy, but I'm not gonna go crazy like many of my fellow Philadelphians.

1:38:17.8 SC: Brent Meeker, says, "In Mindscape 63, the solo episode on finding gravity within Quantum Mechanics, you speculated that there are only finitely many degrees of freedom in a given volume, wouldn't this imply that there are also only finitely many possible states? And so there would be a smallest non-zero probability of any possible event?"

1:38:37.6 SC: The basic answer is no, because Quantum Mechanics just doesn't quite work that way. To say This is a finite number of degrees of freedom means there is a finite number of completely independent states, but in Quantum Mechanics, states are continuous states are any superposition of any set of basis states, as we call them. So you can have a particle spin-up, a particle spinning... That is spin down, so that single particle is literally one degree of freedom, it's either up or down, there's only one particle doing the thing. But how many states are there? An infinite number of possible states, because any superposition of alpha times spin up plus square root of one minus alpha squared spin down is a perfectly good state. There's a smooth continuous spectrum of them, and that is why there's no relationship to anything like a smallest non-zero probability. The probability does not come from the number of states, it comes from those coefficients, the amplitudes and the amplitudes are complex numbers. There are complex numbers between zero and one in magnitude, so it's a smooth continuum of possibilities even if there's a finite number of states.

1:39:49.1 SC: Sean Bentley, says, "Loved your episode on large numbers with Tony Padllia. I'm not as studied on the holographic principle as I could be, so I apologize for the pedestrian question. When removing gravity, why do we go from three dimensions of space down to two and not four dimensions of spacetime, down to three?

1:40:07.6 SC: Well we do... [chuckle] Sorry if that wasn't clear. So we have space and time, time didn't go away when we did the holographic principle, but time is just time, it didn't change when we did the holographic principle either.

1:40:18.4 SC: So when someone says, there's different versions of Holography and in the AdS/CFT correspondence in particular, there's a boundary and a bulk, and the bulk has one more dimension of space than the boundary does, but it has the same number of dimensions of time, namely one. So we don't need to keep saying that over and over again. We can just say five dimensional space in the bulk, four-dimensional space in the boundary or whatever, and spacetime just goes along for the ride.

1:40:49.1 SC: Roman 11 Dob says, "In the context of the show with Barry Lower, specifically when you discuss how the laws of physics can explain anything, Do I understand correctly, the Deutsch and Marletto's Philosophy of Science and Constructor Theory is in the middle between humean and an anti-humean views?"

1:41:02.6 SC: That is counterfactual principles are event producing real and service explanations, whereas dynamical laws which can as Deutsch and Marletto conjecture, be derived from fundamental counterfactual principles are mere descriptions. I think this is probably a super interesting question, and I don't know the answer to it. Sometimes I'll just read out the question because I think that the question is interesting even though I have nothing interesting to say about it.

1:41:27.4 SC: In this case, I don't understand enough about what Deutsch and Marletto would say Chiara Marletto was of course, a guest on the podcast, and you can go back and listen to that. She's a proponent with David Deutsch of what is called Constructor Theory, where instead of thinking of the laws of physics as saying from one moment and all the information in that moment, I will tell you what will happen at the next moment, they speak the language of what is possible and impossible.

1:41:53.9 SC: I suspect that... So, a constructor is something that would make something possible from a pre-existing possible thing. I suspect that it could go either way, the humean view is that the laws are just convenient ways of talking about the world, the anti-humean views, that the laws have an independent existence of their own, and they have some sort of generative role in bringing the world into existence.

1:42:23.1 SC: So I'm not sure I understand the Constructor Theory well enough to answer this question, but to the extent that I do, I could imagine playing that either way that you could imagine that the space of or the division of things into things that can happen and things that cannot happen, itself has an independent existence and brings things into existence by its continual enforcement of what is allowed to happen and what is not allowed to happen. Or that certain things just happen, and that we speak about possible and impossible as a convenient way of summarizing what it is that happens? So I don't think that there is a clean connection there, but maybe one of them would say something different there.

1:43:03.9 SC: Simon Lubinas, says, "Various spiritual and philosophical traditions claim that the universe has a non-dualistic nature. That ultimately the universe and everything in it is one indivisible thing, and that the apparent diversity we see is mirror illusion. I'm not suggesting that ancient philosophers actually discovered Quantum Field Theory, but theology aside, is it scientifically valid to think of the Wave Function of the universe as the only one thing that actually exists? Can we even think of individual objects as being separate from each other if ultimately everything is a manifestation of a single field?"

1:43:37.4 SC: Well, I think this is a slightly tricky question because we come to it with pre-existing baggage about what it means for things to be separate or connected from our everyday life, and when we talk about fundamental physics through the ultimate nature of reality, that intuition is gonna fail us, it's just not going to quite count, so thinking of it in a trivial way, if I have a red block and a blue block, now I have two blocks, right, but also I have one thing, the set of those two blocks, so is it one thing or is it two things. Well, it's certainly both. It's not like it isn't one thing, I have a set of things, and that is a one set, but it's also clearly divisible in an easy way, and the world is like that, the world is clearly divisible in a pretty clear why, we do it all the time. It is certainly at the emergent higher level that we do it, but it's still something that we do.

1:44:34.9 SC: And I suspect the universe is just like that, I suspect that indeed, the Wave Function of the universe is a way of talking about the universe as a single unified monastic thing, but that it is also very useful to divide it up into sub-factors, in fact, they wrote a whole paper about it with Ashmeet Singh called Quantum Mereology. So I think that the categories of being fundamentally one or being fundamentally multiple don't fit very easily onto the question of what the universe really is would be my take.

1:45:08.4 SC: Crystal F Peronski, says, "I love my cats. I enjoy their unique characters and admire their ingenuity, but the same time, I see their intellectual limitations as they can't grasp complex concepts, it seems that the jump from a cat to human intelligence is a qualitative one, then there are quantitative differences between individual people's intellectual abilities. Do you think that there is another level, a qualitative jump above human intelligence, or do you think that for some reason, language ability generalized being universal Turing machines, we are at the most general level already, and any progress from there is just scaling?"

1:45:48.7 SC: I don't know, it's a very good question for a couple of reasons, one is, I am not 100% sure that there is a qualitative jump from cat to human intelligence, there definitely is a jump, but I guess if I were really pressed, I might think that a really really, really noticeable, big, obvious quantitative jump is indistinguishable from a qualitative jump, if cats have an ability to reason abstractly or imagine the future, but that ability is just very, very, very primitive and limited, and we have those abilities that are just much more developed, then it's not a qualitative difference, it's just a difference of degree.

1:46:35.0 SC: So I'm not a 100% sure that I buy the premise of the question. There is a qualitative difference between human intelligence and the intelligence of a water molecule, I think that that is true, 'cause the water molecule has zero intelligence, but I can imagine that there are higher forms of intelligence that really, if once you get down to it, are just capacities that we have, but enormously stronger capacities. We are not very logical, we're not very rational, we're not very good at math, there's a whole bunch of ways in which you could easily imagine improving on human intelligence. Now, if there is a way to be intelligent that is qualitatively different, then I guess I might have a difficult time imagining what that is, so on the one hand, I can't rule it out. But on the other hand, I don't know what it would be. So my suspicion is that it's just not there, but that I can imagine ways that we could be more intelligent and so much more so that it would seem like a completely different kind of thing from our point of view.

1:47:42.2 SC: Chris A, says, "Somewhat moot now as he's thankfully been voted out, but had Bolsonaro been re-elected in Brazil, would it have been ethical to assassinate him to prevent his continued wanton destruction of the Brazilian rainforest on which so much of the world's Biological Diversity depends?"

1:48:00.1 SC: I think there's two ways to think about a question like this one is in some abstract philosophy land and the other one is in the real world. In the real world, no, it would not have been ethical to do that, because if you have a principle that says that elected officials who you think are gonna do terrible things can be assassinated, then a lot of people are gonna take that principle and run with it to assassinate people you don't think should have been assassinated. It's not a matter of deserving or not deserving to continue living, it's a matter of who gets to decide. And the idea that an individual should just take it upon themselves to make that determination is one which we do not want to spread around commonly. I can imagine... I don't think there's a lot of hard and fast rules in situations like this, I can imagine literally a end of the world scenario where you have to assassinate somebody to prevent the end of the world, and nobody else thinks that... They don't see it clearly, so they don't get that and you have to do it yourself, fine, I don't think that any current leader of a country is quite in that category.

1:49:13.0 SC: In abstract philosophy land... I should say, the other thing is, of course, you could be wrong. You could be sure that this person is gonna cause tremendous harm to the world, but maybe you're wrong. So that's why we have institutions and mechanisms for doing things like this. And it would also be different if the person were a dictator and or an autocrat versus someone who was elected. You can argue about whether or not the election is fair, etcetera, etcetera, but in principle, if the people vote somebody in, in a democracy, then I would not be in favor of people in the minority who lost, assassinating that person if they thought that their policies were gonna be disastrous. But then again, yeah, so to get to perfect philosophy land where we grant ourselves the ability to know with certainty that this person really would lead to the destruction of the world, then sure, go ahead and assassinate them. But I think that the difference between abstract philosophy land and the real world in this kind of example is really, really big and important, so I don't think that the in principle conclusion carries much weight in real world deliberations here.

1:50:24.1 SC: John Perry says, "I've just been catching up and listening to your Secrets of Einstein's Equation podcast. It seems inconceivable to me that Euclidean geometry was considered to be the answer without serious question for so long. The sphere, for example, would have been a well-known object to Euclid himself. With the obvious level of historical intellect available, why do you think it survived as the single solution for so long?"

1:50:46.6 SC: Well, I would recommend that in addition to listening to the podcast, you buy the new book, The Biggest Ideas in the Universe, where I discuss exactly this. So, sure, in three-dimensional Euclidean geometry, you could imagine or even construct a two-dimensional sphere embedded in that three-dimensional Euclidean geometry. Construct the set of all points fixed distance from some single point, there you go, a two-dimensional sphere. And you could talk about the geometry of this sphere, but that's exactly the point. The point is, you don't need a new set of axioms for geometry to discuss two-dimensional spheres. Right? You have Euclidean geometry, and the two-dimensional sphere is a subset of the three-dimensional Euclidean geometry. That was the difference when people finally stumbled across hyperbolic geometry, because hyperbolic geometry, negatively curved geometry, if you have a... I don't know. Let me...

1:51:46.4 SC: There's different mathematical terms for this, but if you have a maximal isometric hyperbolic, negatively curved two-dimensional geometry, we always say it looks like a Pringle or a saddle, but those are not... Those are just sort of gesturing at the actual geometry, which is supposed to be completely uniform. That geometry, a uniform negatively curved two-dimensional surface, cannot be embedded in three-dimensional Euclidean space. But it still does have a geometry of its own. So this was an example not just of a geometry that you derived from looking at a subset of Euclidean geometry, but a wholly new kind of thing. That's why it took a long time to do it, and then of course, once you do it, you realize, "Oh, I could have done this with spherical geometry also." So in other words, sure, people knew about spheres, but they didn't think that you needed a separate kind of geometry to talk about them.

1:52:39.7 SC: Paul Cousin says, "How many back-and-forths do your papers have to make on average between you and your reviewers? On which parameter does this depend the most? Topic, length of paper, prestigious journal, etcetera?"

1:52:51.4 SC: It's very different, it's not like there is some medium that you stick pretty close to. I've had plenty of papers just get accepted right away. I've had papers get rejected. Happily, more accepted than rejected. But sometimes they're rejected in such a way that clearly the referees misunderstood something or you made a mistake and you can fix it and then resubmit the paper. So it's usually not that many back-and-forths. I don't want to engage in seven rounds of revising and re-submitting. I would just pick another journal and try again, or even not even bother. In these days, when you have the archive, when you have the online dissemination of papers, to me as an author, getting the paper in a journal is much less important than it used to be. There's better ways. Even when I wanna look at my own papers, it's easier for me to find them on archives than to find them on my own computer. Certainly that's also true for other people as well.

1:53:48.0 SC: But in terms of the parameter that matters the most, in terms of getting rejected, there's some higher criterion in physics for certain journals, like Nature or Physical Review Letters. But honestly, physics has a much flatter notion of journals than many other academic fields do. In many academic fields, your papers are just evaluated by which journals they appear in. Certain journals are really, really hard to get into and getting a paper in there is awesome. Others, anyone can get a paper in. Whereas in physics, the main journals, like Physical Review D, have super, really good papers and also extremely boring run-of-the-mill papers in them. So it's less important to go for those prestige journals in physics than in other fields. It does matter how imaginative, let's say... I'm trying to think of a value neutral terminology here.

1:54:43.3 SC: How creative or non-mainstream your paper is. In many ways, interesting papers are more likely to get rejected. And that sounds bad, but it's actually completely sensible. If I just come up with a model of dark matter or inflation or whatever, that is not super interesting, it just plays by the rules, it does the usual thing, I show that it fits all the constraints and blah, blah, blah. That paper is not gonna get rejected, that's gonna get accepted. It's super boring, but it's also correct in its assumptions. Under its assumptions, the conclusions follow, they're gonna publish it in a regular old journal. Whereas if I try to be dramatically different and I say, "Well, what about this brand new idea?" A lot of people are gonna look at it and go, "No, I don't like that brand new idea," and just reject it. So this is actually not just me sour graping, there are studies that have shown that highly, highly influential papers are more likely to have been rejected the very first time they went to a journal than boring, dull papers. [chuckle] And I'm not even sure how to fix that, but I think that it's something we need to keep in mind when we think about the role of the refereeing system.

1:56:00.7 SC: Declan Brennan says, "Does history have a direction? Some people looking at the Ukraine situation think that Russia doesn't realize the era of colonization is over. Others feel that history has no more of a direction than does evolution. If it doesn't have a direction, does it at least move through phases? If it has a direction, can individuals influence it, or are we all just flotsam on the tides of historical necessity?"

1:56:25.2 SC: I don't think that history has a direction in any especially useful sense, no. Sort of like evolution. If you follow the evolution of the whole biosphere, there are certain patterns that emerge, and you can call those directions. There's sort of increasing diversity of species maybe up until a big collapse, a disaster hits and a lot of species die off, and then it starts growing again. So do you wanna call that a direction? I don't really know. I don't really... I think that the idea of a direction implies that either there is something directing it, or that there's some inevitability about what is going on because there's a direction.

1:57:04.2 SC: Like if you say, "Oh, colonization used to be all over the place, now we don't do that anymore. There's a direction of getting rid of colonies." Well, that might be an empirically true fact, but it doesn't have any control, it doesn't actually have any influence. If one country wants to have a colony and no one stops them, then they're gonna get a colony no matter what the rest of history is doing. So does it move through phases? It's absolutely crucial to history that we can simplify it a little bit. A history book is not simply a list of every event that happens during some period of human history. That would not be sensible. We extract from that. And remember when I talked to Brett along on the podcast, he's extremely upfront that he has a grand narrative that he is trying to use as a lens to view the economic history of the long 20th century, and that's perfectly good. That's why historians have a job because they can notice different trends, different phases that things go through, but it's usually hard to predict ahead of time what that's going to be. We can say after the fact, "Oh yes, here is a single historical era," or something like that.

1:58:19.0 SC: Malte Ubl says, "Given the assumption that the world was created as a random quantum fluctuation, what is the probability that it just now happened rather than happened in the past and from there dynamically evolved to the current state?"

1:58:32.6 SC: Well, I don't think this is quite a well-posed question. I'm not sure what it means to say "the assumption that the world was created as a random quantum fluctuation." I know of no such assumption. [chuckle] There might be random quantum fluctuations within the world, but I don't know of any way to have the world be created as that. I know that people sometimes talk that way, but that's 'cause people are really sloppy. We don't know what happened at the creation of the world, and to say that it was a random quantum fluctuation seems to imply that it was a fluctuation from something to something else. But if it's literally the creation of the world, then there was nothing pre-existing for it to fluctuate from. So that's not what it is. How long was it non-existent before it randomly fluctuated into existence? That's not a sensible question because there was not even time before that moment happened. So I don't think that that's an idea that is really on the market, the world was created as a random quantum fluctuation.

1:59:31.4 SC: There is absolutely an idea on the market that the world had a beginning. But if the world had a beginning, the world in terms of the whole universe, that just means that there's a first moment of time. It doesn't mean that that first moment of time fluctuated out of a pre-existing nothingness. That is literally the wrong way of thinking about it. It's no more or less than the statement that the universe had a beginning, just say that. Don't say it came out of nothing or anything like that. As far as the probability is concerned, yeah, I don't know. [chuckle] I could easily imagine a whole bunch of different quantum states that give rise to different probabilities. And the quantum mechanics that we know and love, there is a probability associated with different measurement outcomes given any one particular quantum state, but if you don't know what the state is you have no idea what the probability of different possibilities are. So again, I think it's a little bit of an ill-formed question.

2:00:28.7 SC: Connor Cheffron says, "Unless I've mis-counted, you've only had three episodes that discuss climate change as a main topic, with the most recent being three years ago. It seems like there are a lot of smart people with expertise in climate science who are saying that climate change is the most urgent issue facing humanity at the moment. Is there a reason you don't talk about it more these days?"

2:00:47.7 SC: Well, there's zero connection between what I think is the most urgent issue facing humanity and what I need to have on the podcast, otherwise, I wouldn't have podcasts about music and wine tasting and things like that. There are far more urgent issues facing humanity. That is not the decision procedure I go through. It's more like, is there an interesting thing to talk about? Is there something we can learn from having this conversation?

2:01:10.2 SC: And obviously, climate change is super duper important and super duper interesting, but I'm not gonna do a podcast just to sort of reassure ourselves that we're virtuous about it. Just to say, I never believed in the therapeutic value of complaining. When Donald Trump won the election in 2016 and there was a period where you couldn't have dinner with people without it just being like, "Oh no, the world is ending. Donald Trump is president, things are bad." And I agreed that things were really bad, but my response was always, "Okay, well, what are you gonna do about it? Why are we having this conversation? Is it just to get it off our chest? We just feel bad, we wanna kind of yap about it ineffectually?" And I just never saw the point in doing that.

2:02:00.9 SC: I will talk about democracy a lot, and I think the democracy is in trouble, but I don't just have a whole bunch of podcast saying, "Democracy is in trouble. This is bad." I try to analyze the ways in which democracy is in trouble, whether democracy could be improved, whether it can work better. There's a whole bunch of intellectually interesting questions there. When it comes to climate change, there's a whole bunch of intellectually interesting questions about climate science and atmospheric science and so forth. I'm not especially an expert on those myself, and I'm not quite sure which ones would make good podcasts, but I don't wanna just have a podcast saying, " Climate change is coming and it's bad." I assume that over 95% of my listeners already know that, and I have zero interest in just telling them something they already know. That's not what we're here to do.

2:02:49.1 SC: Tarun says, "In your recent discussion with Barry Lowe, you seem to agree that the Humean view in relation to laws of nature is the correct one in comparison to what you called the God view. However, I was then surprised to see that in the last PhilPapers Survey, the majority of philosophers stated that they accept or lean toward the non-Humean view, this is despite the majority having atheistic views and subscribing to naturalism. Why do you think that is?"

2:03:14.7 SC: So I think that... I didn't wanna call the anti-Humean view the God view. That was Barry's terminology, and he was being a little cheeky in doing it because we're both Humeans. We're all Humeans here. Just have a good slight poke at our anti-Humean friends. I don't know of any anti-Humeans who call it the God view. There is a family resemblance behind the idea that the laws of physics have a separate identity to the physical universe, and the idea that God has a separate existence in addition to the physical universe, but they're not necessarily connected in any way. There's plenty of atheists who are anti-Humeans. Okay? So don't take the phrase God view too literally, is what I would say.

2:03:58.4 SC: James Allen says, "Briefly, in your debate with William Lane Craig, you mentioned that modern physics doesn't use Aristotelian notions of cause and effect. Is there a place in the literature that clearly expressed that view? Such a citation would be valuable in the corners of the inter-webs where atheists hang out."

2:04:14.1 SC: Yes. It is the book, The Big Picture by Sean Carroll. I can highly recommend it. With one footnote, I talk a lot about cause and effect in that book, and I talk about Aristotelian notions as well. But because people continually misunderstand this, let me be very clear, I am not an expert on what Aristotle himself actually said, nor do I really care what Aristotle himself actually said. That's not the point. I am using Aristotle as an exemplar of a tradition that puts cause and effect front and center in our understanding of the dynamical evolution of the world, and furthermore, in front and center in our explanatory framework of the world. This tradition goes all the way up, at least to Leibniz and the principle of sufficient reason. So it's not Aristotle himself that is really, really important here. What's important here is the idea that causes are fundamental in the universe rather than higher level emerging phenomenon. That's really the distinction that is important to me in that book.

2:05:18.2 SC: Jimi, says, "Is there an asymmetry between position and momentum in the Hamiltonian? If so, doesn't that mean that they aren't as practically equivalent as it sometimes seems?"

2:05:32.0 SC: So yeah, if you think about Hamiltonians in physics, the Hamiltonian is at some level, just a simple way of saying what the energy of the system is. But there's a specific way in which the Hamiltonian comes about, namely when you're using as your coordinates on the space of all possible states, positions and momenta. Okay? So the Hamiltonian is a function of position and momentum, and it's the function that says, here is what the energy of the system would be if it had this position and this momentum. Read more about it in, The Biggest Ideas in the Universe, where I talk about Hamiltonian mechanics.

2:06:07.0 SC: As far as there being an asymmetry in there, it depends on what you mean by the Hamiltonian. In Hamiltonian mechanics, you're allowed to write down any Hamiltonian you want, and position-momentum are perfectly symmetric. You can write down any function of X and P or any function of P and X. Just as well, those could be Hamiltonians. In the real world, the Hamiltonians we actually use to describe physical systems are not arbitrary, they're kind of specific. And in those specific Hamiltonians, there is an asymmetry between position and momentum. One simple way of saying it is, particles will interact with each other, more strongly at least, when they are nearby in position. They bump into each other or they have an electromagnetic or gravitational effect on each other, etcetera, as a function of position. The interaction there has nothing to do with whether their momenta are close to each other. There's no principle in the real world that says, if two particles have the same momentum, they will interact in some strong way. That's just not a thing. And that difference can be traced to the fact that P and Q, momentum and position, appear differently in the Hamiltonian of the real world.

2:07:19.6 SC: Joshua Hillerup says, "Do you think poetic naturalism could be applied to ethics? For instance, could there be some sort of fundamental consequentialism that's about as useful for making actual ethical decisions as the standard model is for engineering a building, but it could be used to build up other ethical theories more specific to given domains in a similar chain to what we see in science?"

2:07:40.0 SC: I think that's very possible. I think that Joshua Green actually gestured in this direction where he tried to say that he didn't perceive as much of a difference between utilitarianism and deontological theories as some people do. And even Will MacAskill said that we can sort of consider the median or some superposition of consequentialism and deontology. However, I don't necessarily know that the fundamental level would be consequentialism. I think the way that I would put it is, what you could say is, is there some fundamental moral theory, and it doesn't need to be objective, it can be something constructive, that's fine, but it's supposed to apply to all situations, all circumstances and be universal in some sense, even if not everyone agrees with it, but some people do.

2:08:26.2 SC: If there were such a theory, but that theory was so wickedly complicated in practice that we would get in trouble if we had to sit down and work out what the consequences of that theory were in any particular circumstance. So instead, we use rules of thumb and approximations at that higher levels. I think that's extremely possible, whatever that fundamental level actually is, and probably something like that is what we actually aspire to do in the real world.

2:08:56.6 SC: Policy Conte says, "I was wondering now that you're at Johns Hopkins, if you would be given any preference in submitting an observation proposal for the JWST? If you could submit an observation proposal to the Committee, what cosmological or astrophysical question would you consider investigating?"

2:09:13.3 SC: Well, I'm allowed to consider to submit observation proposals. As far as I know, there is no preference for Hopkins faculty for JWST. I don't know if you're an astronomer yourself, but very often universities or research institutes will buy a fraction of a telescope. So you have a big telescope that has many institutions using it, like the Keck telescopes in Hawaii were a joint between Caltech and the University of California so there's different University of California campuses and there's Caltech, and the professors at those institutions absolutely get preference when it comes to submitting proposals.

2:09:56.9 SC: But the JWST is a NASA facility, so if anyone is gonna get preference, it's gonna be NASA employees. I don't even think that they get preference, to be honest, I think it is supposed to be a national or even an international good, the space telescope. And so anyone can apply to it. I myself have zero plans on proposing anything like that, I'm gonna leave that to the experts. It's the kind of thing where you gotta know what you're doing, it's one thing to say, "I would like to observe something," but there's a lot of real knowledge of how it is done, practical knowledge that you need to learn the hard way by training with someone who knows what they're doing and learning and stuff like that. And as a theorist, I haven't done any of that, so I'm gonna leave that to the experts. If I have a theory I want tested, I'm not gonna put in the JWST proposal, I'm gonna go to my friends who are good at this and say, "You should test my theory." That I might very well do.

2:11:00.6 SC: Nalita Ess says, "What is from your perspective preventing us from finding dark matter, given its immense influence? Do you think we will ever be able to spot it like we did other elementary particles?"

2:11:10.5 SC: Well, that's certainly the hope. There's no... As Martin Rees has said, former Mindscape guest, now that I think about it, it's not surprising that there's dark matter in the universe in the sense that all dark matter is, is some particle that has the substantial abundance of mass in the universe that doesn't interact either through the strong interactions or the electromagnetic interactions, how hard is that? That's not. It's very, very easy to go up with ideas or particles like that. Indeed, neutrinos are absolutely particles like that, they are not the dark matter that we know about in cosmology, at least we don't think that they are, because they move too fast. Okay? They're too low mass and high velocity to fit the detailed properties that we think dark matter has, they would be hot or warm dark matter, whereas cold, dark matter is what fits the data, but they are an example of particles that are dark and are matter. So there you go.

2:12:04.4 SC: And we've detected them also, so we absolutely hope to spot it. We've talked about that on the podcast, with people like Lina Necib, if you wanna go back into archives. But we haven't spotted them yet, so we're still looking. I don't know, you'll know, if we find it you'll definitely know.

2:12:24.7 SC: Brent Jones says, "I teach AP chemistry and AP Physics at a rural high school in West Virginia, and I absolutely love going to work every day. Now that you're teaching again, I'm curious to know what you love most about teaching."

2:12:37.4 SC: It's probably the wrong time to ask me that as I'm kind of swamped with teaching right now, there's a lot of work involved in teaching apparently, who knew about that. But there's so many things I also love about it, and I can't deny that. I love it when I'm able to say something that suddenly makes a little light bulb go off in the student's head, especially when that light bulb is, "Oh no, I've been misinformed about something my whole life." I'm teaching an upper level undergraduate seminar on the philosophy of physics, and there's plenty of places where you can point out that, here is what we get taught in our physics classes, and here is the completely different truth, and you see the students go like, "Oh my goodness, yes, I was taught that. You're right." And so that's always fun.

2:13:24.3 SC: It's also just fun to talk individually to the students. To me, the years of your undergraduate education are, in many cases, the most important informative of your life, because you go from having been in the same environment or a very, very similar environments for most of you are going up and then suddenly you're in a completely different environment with completely different friends, learning new things at a high level, doing different things, and then that sort of sets you on the trajectory of the rest of your life. So I worry a little bit, you talk to students and you always worry that you're gonna say something that will turn out to be really crucial for their life, and you were just saying it kind of randomly. So there's a responsibility there, but I do like the idea that I can help students navigate this very, very important and fraught period of their lives. I have usually in my teaching past been teaching upper level Physics classes where the students were more or less on a trajectory already, either graduate students or very upper level undergrads. Now I'm teaching a more diverse set of undergraduate students at different levels of their career, and so a lot of it is like, "Yeah, I have no idea what I wanna major in yet." And there are a couple of words here and there can have a big impact. So it's something to take very seriously.

2:14:49.1 SC: Dave says, "According to black hole holography, does Hawking radiation convey information about the state of an object when it hit the event horizon and only? Or rather a history of all of its states inside the event horizon until it hits the singularity?"

2:15:01.6 SC: Well, technically, there's no difference between those two things. If you believe that information is conserved, which is one of the motivating ideas behind holography, etcetera, the information from one moment to the next is the same information, just sort of scrambled by the historical evolution. So knowing the whole universe [2:15:20.9] ____ at one moment of time is equivalent to knowing it at any other one, and that goes also for objects falling into black holes. So we talk about the quantum state of the black hole as if it was a constant thing, but even if it's evolving, it goes from one state to another in a way that is strictly determined by the equations. So that set of information, whatever it is, however you wanna present that set of information, that is what is supposed to be taken away by the Hawking radiation, if information is conserved.

2:15:54.0 SC: Redmond says, "On atheism, does a strict materialist who rejects not only traditional concepts of a deity, but any higher organizing principle whatsoever, assume the burden of proof?"

2:16:05.3 SC: Well, short answer, no. Longer answer is, what do you mean, the burden of proof? Burdens of proof are an idea that that's a concept that applies in a legal proceeding. Prosecutors have the burden of proving that the guilty person really did it beyond reasonable doubt, in a civil proceedings, the burden of proof will be different and so forth. If you're just talking to someone and you are mutually trying to find the truth, no one has the burden of proof, you should be working together. It's very, very... Using legal proceedings as a paradigm for finding the truth is a very, very bad way of finding the truth, let's put it that way. There's much better ways of doing it as an intellectual endeavor. If what you mean is, does rejecting traditional concepts of a deity and a high organizing principles somehow deserve less a priori credence than assuming a deity or whatever, then no. That doesn't seem at all right to me. If anything, assuming a deity is one extra thing to assume, and therefore you should have a reason for doing it, but I wouldn't call that reason a burden of proof.

2:17:18.7 SC: Jeff B says, "Imagine that a simple object like a paper clip is floating in empty space, for the sake of argument, suppose that the paper clip is shielded from interacting with the environment in any way. Now, we could imagine waiting some amount of time and observing the paper clip. Am I correct in saying that the longer we wait, the more branches will be created when the paper clip is observed? If so, is this mostly due to the larger number of radioactive decays the paper clip has undergone, or is it mostly due to the paper clip gradually spreading out over Hilbert space?"

2:17:50.9 SC: I'm always a little leery of questions involving counting number of branches. If the number of branches is infinite, there's no way to count, you can integrate over certain sets of branches and get a weight that you can apply to them, but the total number is infinite, so it's not like there are two more branches in some period of time or anything like that. The interesting part of your question, the quantitative part, I do think that in some sense, at least morally, yes, more branches are created the longer you wait to observe it. You don't have to put it in a box to make that true, you don't have to shield it from interacting with the environment.

2:18:28.2 SC: Just let it interact with the environment and branches will be created all along. And the number of branches created or not any different if you're just looking at the paper clip the whole time than if you're letting it float freely in space. And both of the effects that you mentioned, a spreading of the Wave Function of the paper clip itself and the fact that there are radioactive elements within the paper clip they'll will both contribute to branching the Wave Function of the universe. How many of them? Yeah, I have no idea. [chuckle] As I said, I truly don't care about these questions about counting the number of branches, that's just not where the interest to me lies. Maybe that's an answerable question, but I just don't know what it is.

2:19:10.0 SC: Chris Murray says, "In a closed universe, if you put many black holes close together in a straight line all the way around the universe, could they merge to become a black tube but with a stable cylindrical horizon? And what would that be like?"

2:19:23.4 SC: This is a very interesting question because the short answer is, no. There would not be a black tube with a stable cylindrical horizon, but it turns out that that answer depends on the number of dimensions of the universe, and also on the size of the universe. So there are things called Black strings, so a black hole, but rather than being a sphere is like a one-dimensional tube, just like you say, not in our three plus one dimensional spacetime, but maybe in compact dimensions of space, you could have such a thing. And the reason why it would not be stable is you can increase the area just by beating it off into individual black holes, and that increases the entropy, and that's what you wanna do in terms of what black holes tend to do. You always wanna increase your entropy.

2:20:11.8 SC: Casey Mahone says, "Experiences of aesthetic beauty can sometimes feel transcendent and divine, but from a material standpoint, these experiences must be rooted in our evolution. What do you speculate is the evolutionary basis for these sorts of overwhelming mystical or artistic experiences?"

2:20:30.1 SC: Well, I don't know, is the short answer. But I can at least say that it's completely unsurprising to me that there are such mystical or artistic experiences, the human brain is a complicated place. Evolution is a complicated process. It's not a straight line design in order to fulfill some goal. The shifting demands of our environment and the situation we're in, put different evolutionary pressures on our brains at different times. And also because it's not designed, we have to work as previously mentioned, with this framework of looking at random fluctuations in the underlying blueprint from the DNA and seeing how they play out in the real world, which is a very hit-or miss way of doing things. So we end up with systems in biology, whether it's the brain or otherwise, that are in many ways, not well-designed. Enormously powerful, but a lot of redundancy in some places, fragility in other places, inexplicable wiring choices in yet other places and so forth.

2:21:32.2 SC: So it's not that we are evolutionarily chosen to have transcendent experiences, but maybe there is some reason or even maybe it was just random, that transcendent-like experiences played a good role, being happy, not being drawn down or depressed by the moment. Sort of being able to think more why be about big questions, these are all things that I can imagine have a good evolutionary purpose to them. So I don't know the specific answers to this question, but the brain is a complicated place and it makes zero difficulty in my mind to imagine that something like that could evolve.

2:22:17.5 SC: Floyd Alteryx says, "Could you explain how a dragon would breathe fire in the fantasy world?" So this is another one, I think I'm getting more and more interested in picking questions to which the answer is, I don't know, [chuckle] or you shouldn't ask that question. But for this one, this is... I don't wanna read too much Floyd into your asking of the question, but there's a whole genre of discussions that I am very familiar with, having worked as a consultant on the Hollywood movies and so forth, which is taking something that appears in a fantasy or not very grounded science fiction story and exposed facto trying to come up with a sciency plausible explanation for it. Okay?

2:23:01.8 SC: The real answer is, because the author wanted them to. That's how a dragon can breathe fire. Dragon don't really exist, they couldn't be able to fly if they did exist, and so why not have them breathe fire. It's kind of fun. Right? That's the actual real answer. Now, if what you mean instead is what is the most biologically physically plausible way to get a biological creature to breathe fire? That I also don't know the answer to, but it's actually not that difficult to believe, probably just for safety considerations, what you would want is not to actually be able to breathe fire, but to belch some sort of highly flammable gas in an environment where things light on fire all the time by themselves 'cause there are sparks or electrical currents or something like that. That seems to be a little bit more safe than actually starting a fire inside you and then breathing it out, that doesn't sound very safe at all. And if that's the way you're doing it, if you're just belting out gas, we belch out gas all the time, there's no special evolutionary reason why the gas should be highly flammable, but if you really, really, really wanted it, I could imagine that an organism could do that. So that would be my guess, there's probably other ways to do it.

2:24:25.4 SC: And even better way if you were able to design rather than just build it biologically, what you might want is to have two gases which are separately perfectly stable, but then when they're combined, they become highly flammable. That happens all the time, it happens in rocket ships, right? Hydrogen and oxygen can be kept separate, but then when you put them in the same region of space, they burn very, very easily, so that might be another way for dragons to do this. I don't know how dragons get a large collection of hydrogen in them, but it is a fantasy world after all.

2:25:00.5 SC: Christopher Becks says, "I recently read on New York Times article about a German heiress leading a movement to have massive inheritances go almost completely to taxes and redistributed by the government, the thought being that redistribution versus philanthropy reinforces existing power structures by allowing the ultra-wealthy decide where the money goes."

2:25:19.0 SC: I like the spirit, but feel like it puts a lot of faith in government to use this money well, and actually reinforces International power dynamics by keeping money in countries with more ultra-rich people. Well, it's always, compared to what? I presume that what you're imagining or contemplating is comparing some very severe kind of inheritance tax, that when people die, their fortunes are heavily taxed, versus letting the wealthy family keep it and decide how best to philanthropically spread it around. And I think that I don't want to eat the rich or kill the rich or anything like that. As I often said, I'm in favor of rich people. I wish I were a rich person, and I'm okay with allowing rich people to enjoy their money, to some extent. At the same time, I do think that there should be inheritance taxes, and I think there probably should be a lot more than there are. And I think that the argument that, "Well then, the government has to use that money well," is pretty easily defeated by just looking at how the government would typically use that money versus how a wealthy individual might use that money.

2:26:31.2 SC: Many wealthy individuals are very good at doing philanthropic good to the world, but it certainly has the failure mode that you have someone with quirky interests. They have a lot of money and they're gonna spend on things that they think are interesting, and that's their right to do so. I'm not against that. But the government has different interests, the government has the duty of thinking about how best to spend all of the money on all of the needs that people have and do so in a responsible way. Does the government always do a good job at that? No. But at least it's their job and we can try to make them do a better job at it. I'd be very much in favor of all sorts of higher taxes on richer people, and then separately, work to make the government spend the money as well as we can. It's very down-to-earth kind of boring policy proposal, but I'm in favor of that.

2:27:26.2 SC: Peter Solfest says, ""In Episode 200, you seem to make the argument that considering yourself as a Boltzmann brain is cognitively unstable, so we shouldn't think of ourselves as Boltzmann brains and thus should assign lower credences to theories that predict there are a lot more Boltzmann brains than other observers. I follow the logic to not thinking of myself as a Boltzmann brain, but why should that give me the leverage to lower my credence about cosmological theories that predict them? In other words, I get that I should behave as if I'm not a Boltzmann brain for practical reasons, but why should that give me theoretical grounds to make any statements about which theory is better?" Well, I'm not sure I quite buy the difference between the two things. Behaving as if you're not a Boltzmann brain for practical reasons, but not theoretically accepting it.

2:28:10.9 SC: I think that you should behave in accordance with whatever view of the world you actually accept is likely to be true. And the point about the cognitive instability of Boltzmann brains is, it's no way to go through life accepting that because you can draw no conclusions, you do not know anything about the world, if that's the cosmological scenario you accept. I don't think there's a difference being saying, "I think this is true, but I'm gonna act as if something else is true." I can't imagine a principal justification for doing that. You might be in trouble if we lived in a world where there was no better theory, there was no way to assume that we are not Boltzmann brains and get a coherent picture of the world. But there is. It's pretty clear that we can assume we're not Boltzmann brains, that there is actual regularity in the world, there is a low entropy past that we evolved from, and all that stuff. All that fits the data really, really well. So you do have the ability to construct cosmological models that are both potentially true and sensible and fit all the data. I'm gonna advocate doing that.

2:29:19.6 SC: Fyrass says, "I've noticed that whenever a scientists talk about the state of the universe and associated big theories, they never really add the small asterisk that it's all from the perspective of humans and from our location in space. Do you think this creates a form of scientific absolutism where we fail to recognize that the rules that govern our reality only really makes sense from our observer status, from our perspective?"

2:29:41.5 SC: Well, yes and no, I wouldn't put it that way. The short answer there is no, but it is absolutely true that we are highly conditioned on what we are able to observe. Sure, there are some things that are easier for us to observe, easier for us to notice than other things and that guides our scientific theorizing. There was a reason why Aristotle and Galileo and Newton came up with their theories before we came up with quantum mechanics and the standard model and gender relativity and things like that. Our knowledge of the world was much more limited back then.

2:30:14.9 SC: But it's not a kind of absolutism. Newton... I don't know what Newton thought, but he should have thought that maybe someday we'll know more and change our minds. That's what we do as scientists. We do our best to understand the universe to uncover the patterns, the laws that it obeys, and we imagine that maybe those patterns and laws continue to be true elsewhere, and then we test that idea. We say, "If that's true, what would we predict? What would you observe?" And we go looking for it, that's how science works, and we need to be careful of our biases, etcetera, but we've gotta work with what we can work with, and there's no absolutism about it.

2:30:53.8 SC: Krather Luca says, "Why do you think many worlds is still not the consensus view for the foundations of quantum mechanics?" Well, I do think that there's perfectly good reasons why many worlds should not be the consensus view. I don't think that they're right, but they're decent reasons. I think the basic reason is the simple fact that the metaphysics, the underlying view of the world presented by many worlds, is radically different than the view of the world that we're familiar with from our everyday experience.

2:31:22.8 SC: And, on the one hand, you should expect something like that. Who's to say that the true underlying theory of reality should in any sense map in any easy way onto our everyday experience, but on the other hand, when you actually have a proposal for the underlying structure of reality, you should be cautious. The thing about many worlds is it's a very easy theory to state, there is a vector in Hilbert space and evolves under the Schrödinger equation, but there's a lot of work to be done in connecting that simple underlying theory to our observations and our experiences. And there's an obvious way to go wrong if we think we know already what our observations and experiences are. I wrote a paper about deriving the Born rule from the many-worlds interpretation of quantum mechanics with Chip Sebens, we've already mentioned, and I think that I agree with the logic we put forward there. But I have to be honest in that we knew the Born rule ahead of time. [chuckle] We weren't gonna write a paper deriving a different rule. It's easy to fool yourself in those situations and exactly, because the fundamental structure reality suggested by many-worlds is so different than the world we observe, it's perfectly okay to be cautious, to be tentative about it.

2:32:43.6 SC: And other theories map on more directly to the world. In a hidden variable theory, the reason why you see particles is 'cause there are particles. That's very basic. And in objective collapse theory, the reason why weigh-functions seem to collapse is 'cause they collapse. And that makes the theory uglier and more complicated and harder to generalize, but also easier to understand in a very direct way. So that's okay. Eventually, everyone will be on the side of the angels and agree that many-worlds is right.

2:33:14.7 SC: Steve Galore says, "Do you have any anecdotes about your interactions with William Lane Craig? I've seen quite a few WLC debates, and yours is probably the one that has challenged his scripted talking points the most effectively. You had some help from Alan Guth as I recall. What are your recollections of the times you have debated him? Any chit-chat before or after? Thinking back, are there any additional things you wish you had said or things you would now put differently?"

2:33:39.2 SC: No, we didn't chit-chat that much, we chit-chatted a little bit. We didn't pre-plan anything for the debate. He's debated many times. He has a system, we're not gonna deviate from the system. It's either, when I get invited it's like, "Do you wanna do this or not?" There's no negotiations. And we only debated that once, so I don't have repeated interactions. We did go out to dinner afterward, but we went to dinner with like, 20 people, so even there, there was not a lot of chit-chat. He was very gracious, he complemented me on my debating at the end of the whole thing. I didn't convince some of anything. He later wrote a bunch of blog posts and did interviews explaining why I was wrong, which is not surprising. As far as what I would have done differently, I don't think I would have done that much differently, but I would do it differently were we to do it again. I don't think we will. We have no plans, there's... Life is short and I did that once, I'm not planning on doing it again. But if I change my mind and the world changes and we do do it again, I would approach it very differently, not because I think I shouldn't have approached it the way I did, but because I already did that.

2:34:42.3 SC: So there's a different way to approach it. And the approach I took in the actual debate was, I'm not interested in winning the debate in the sense of a high school or college debate competition. I was on the debate team in high school, I know what it means to win, to go point by point by an argument and refute the arguments, etcetera. But that's a very, very stylized way of discussing things, it has nothing to do, as we have already said previously with the burden of proof and legal proceedings, it's not about the search for truth. My goal in that debate was less to sort of score points and more to explain myself, more to be understood. Given that there is an audience, and some of those... It was literally at the New Orleans Baptist Theological Seminary so the audience was stacked against me. But as long as there are young people, I don't mind. Young people will always listen, old people are a whole different story. But I wanted to help them understand why someone would be an atheist and yet be rational and even maybe a good person. That was my goal.

2:35:50.8 SC: And so I hope that I succeeded at that. Why the arguments from William Lane Craig were not logically airtight, because they are not, and also why there is an alternative that works very, very well. We each... He spoke and then I spoke, then he spoke then I spoke, then he spoke then I spoke. And by the last of my three little speaking slots, it was short, but I had already said everything I wanted to say. I had refuted his argument in his most recent... In his final speech, I don't think that he said anything new or rebutted any of my arguments. So I didn't even try in the third part of the debate to refute anything he had previously said. I think that I'd done that already so I just gave my sales pitch for why naturalism is a very fulfilling and rewarding way of thinking about the world. And I think that's exactly what I should have done, and I'm very happy that I did that. If we were to do it again, maybe I would actually try to win the debate [chuckle] in the sense that I would... Having given my sales pitch for naturalism, maybe I would just focus in more on why his pro-theism arguments aren't that compelling. Or maybe not, I don't know, but that would be a different style, which could be equally effective depending on what your goals were.

2:37:12.6 SC: Claudio says, "I lived 32 years in a country with mandatory voting, and 20 in a country where voting is not mandatory. I strongly favor making voting mandatory. My rationale is that for proper democracy, the government must be representative. This is, its composition should be as proportional to the people as possible. What's your position on mandatory voting?"

2:37:33.4 SC: I don't have a strong feeling. This is a case where I think that the, whatever feeling you do have should be informed by the data. In other words, I don't think that there's any philosophical or moral argument that would completely persuade me to be either for or against mandatory voting, but if it actually in the world led to do better results than I'd be in favor of it. I don't actually know any sort of unbiased systematic survey, whether or not it leads to better results, or even what it means to say that it leads to better results so therefore, I'm agnostic on that one.

2:38:10.4 SC: Brian says, "Antonio Padilla said that, 'We can't picture Graham's Number because it contains too much information', but then I wondered, can you picture Pi? There aren't enough atoms in the universe to do that in your head either but we have it defined, the same for Graham's Number. Maybe the question is, what is the significance or are there any implications from the fact that we can't hold it fully in our heads?"

2:38:32.3 S2: So you're right that in the case of both Pi and in Graham's Number, we have a definition of it. And we can write down that definition in a finite number of bits, a finite number of instructions to calculate the number. But if we were to actually write out the number, the story changes a lot. Graham's Number is very, very, very long. Pi is literally infinite. If you write out the entire decimal expansion of Pi, it never ends. There was never any question of holding the decimal expansion of Pi in your head, it's just infinity is bigger than a finite number, so you can't do it. It's sort of not an interesting conjecture.

2:39:10.4 SC: The thing that Tony was making, the point he was making about Graham's Number, is that it is a finite number. You might think you could hold it in your head. No one ever thought you could hold all the digits of Pi in your head, but you might think you could hold all the digits of Graham's Number the number in your head, but you can't. Because the storage capacity of the brain that would be necessary to do that would collapse into a black hole, that is the implication. It's a little bit different just because Graham's Number is long, but still has a finite length.

2:39:43.2 SC: I'm gonna group two questions together. James Swift says, "I sometimes struggle with how mathematicians use the phrase, 'Solve the equation.' It's easy to understand when someone says solve F for X, but when just generally stated statements... " Sorry, I am reading this with a bad inflection here. "But when just generally stated, statements like, 'Schwarzschild solved Einstein's equation,' I feel a little lost. Can you give guidance about how to understand such statements? What is being solved?"

2:40:12.3 SC: And Billy Weston says, "I'm trying to learn some basics about Einstein's field equations, and I feel I am missing something simple in my understanding of the significance of them before and after they were solved. Were Einstein's equations in 1915 simply incomplete, but still obviously important? What does it mean for an equation to be revolutionary without solutions yet found?"

2:40:33.7 SC: Yeah, I want it very much to answer this question, but you're kind of making me feel bad because I'm realizing that this notion of having an equation and solving it is perfectly clear to me, but maybe I didn't make it clear in the book or elsewhere. And it's not fair to think of it as an obvious notion because it's not an obvious notion. The notion is, if you have an equation like 2 + 2 = 4, that's an equation, there's nothing to do with it, you can't solve that equation, it just is the equation. But when you have algebraic or analytical equations, you have equations with undetermined parameters in them, you have not just numbers, but symbols, to put it very basically. You've elevated your mathematical technique from numbers to letters.

2:41:21.0 SC: Let's say you have X squared equals four, X squared equals four is also a perfectly good equation but you're not done when someone hands you that equation. Here's X squared equals four, that's the equation. The question is, what is X? And you know the answer, X is two, except also X equals minus two, so there's two solutions, and that's a little bit of a subtlety that you can talk about, but finding the actual value of X that satisfies that equation is what we mean by solving it. And Einstein's equation and general relativity is exactly the same structure, except what you're solving for is the metric, the geometric quantity that tells us the curvature of space time. We have a metric, it's G mu nu, if you're reading the book. And what we do is we write an equation containing G mu nu in various forms, but the equation itself doesn't instantly tell us what the solution is, what the actual value of G mu nu is. When Karl Schwarzschild solves Einstein's equation, we had the equation, but we didn't know that there was a solution of the form G mu nu equals the Schwarzschild solution.

2:42:31.1 SC: So Einstein, when he wrote down his equation in 1915, the equation was complete. It was done and he instantly solved it in various approximations, in fact, honestly, he had essentially solved it before he wrote it down because he had approximate versions of the equation itself. But he didn't have any interesting exact solutions, those came later. So you can propose an equation and have a very good reason to believe that it is correct, not... You can't be sure, 'cause you're never sure in science, but you think it's correct without yet knowing what the solutions are. Einstein's method was to find approximate solutions, and that's why he could still explain things like the deflection or the precession of the orbit of mercury, for example, he could show that that was a prediction of his equation without solving it exactly because he was solving it approximately.

2:43:22.9 SC: Brandon Hall says, "Do you ever do problems or exercises from a textbook when you're trying to learn a new subject these days?" You know, sometimes. I'm not that devoted to it. [chuckle] But I guess the reason I want to answer the question is to emphasize that there is a part of learning which, one way or the other, is the equivalent of solving exercises from a textbook. And this is precisely what we don't do in the Biggest Ideas In The Universe, that's what makes it possible to fit all that information into such a short space in the book, we don't tickle that part of your brain. We do not teach you how to solve exercises or solve the equation, etcetera. I'm a very firm believer that if you truly want to learn something, you can't just know the equations, but you have to know techniques for solving them, for doing the problems, for doing the exercises. And that's really how you learn it, as unpleasant as it is in your student days. So if I... I don't have a good example right now off the top of my hat, but I have... Well, here's an example, I have a book on the bookshelf next to me, that seems to me like it'll be an amazingly good book as a textbook for a course in a physics course on complex systems.

2:44:37.1 SC: It's by Stefan Thurner and collaborators called Introduction to the Theory of Complex Systems from Oxford University Press. I have an aspiration of some day teaching a course on the Theory of Complex Systems, which is something that I only know a little bit about, so if that ever happens, I will certainly go through this book and try to do exercises in it. But I haven't done that yet so that's why it's not a great example.

2:45:00.4 SC: Eric Strongquist says, "On the question of probability in the ever interpretation, the leading ideas from you and Sebens, from Wallace, earlier Deutsch, all successfully explain why the Born rule should work, but they don't explain the mechanism. How is it that the great majority of, or the greatest measure of observer moments with their memories of a series of measurement results end up distributing in the weigh functions so that an observer chosen at random has usually observed just about the right quantum statistics?"

2:45:28.3 SC: I kind of wanna un-ask this question. I don't buy the presumption of the question, the underlying philosophy of it. It's cheating when you say, let me read it again. "How is it the great majority of observer moments end up distributing the weigh function so that an observer chosen at random as usually observed just about the right quantum statistics?" That completely begs the question, what do you mean by chosen at random, in many worlds, there's gonna be many different observers, and the whole question is, what do you mean by choosing at random. The thing about many-worlds is, let's not over-complicate this. It is crystal, 100% super-duper clear that if you think that the theory implies any probability rule at all, that probability rule is going to be the Born rule, there was never any chance. It was gonna be the probability is equal to the wave function or the way function to the fourth power or whatever, it's.

2:46:25.4 SC: Just Pythagoras there, the hypo new square is the sum of the squares of the sides. That's where the Born rule comes from. The right thing to do is to justify why there is a probability measure at all, and I think that that's what Chip Sebens and I did. We told you why there is a probability measure and why it acts like the Born rule, because they're a self-locating uncertainty, so I don't think there's anything more to be done in the cause of explaining the mechanism. I think we did explain the mechanism, self-locating uncertainty when the way function branches. That's the mechanism. I suspect that your thought that we haven't explained the mechanism is a relic of the thought that if you have probabilities, they have to reduce at some point to literally counting, counting a certain fraction of things. If you think that there's a 30% chance that X and a 70% chance that why then somewhere in some abstract space, there are 30 Y and 70 X or something like that. That's just not how many worlds works, and so I don't feel that need to satisfy that itch in order to say that I have the mechanism, I think I know exactly what the mechanism is.

2:47:40.4 SC: Andrew Goldstein says, "I read things like The October 30th, Washington Post editorial, which tried to provide some insight into the volatile activity of the stock market and the fortunes of the mega-wealthy, it leaves me even more confused, therefore, I wonder whether you see any potential for more sophisticated understanding that would give us better knowledge how to forecast the complex social behaviors and interactions observed in humans, but poorly understood."

2:48:09.7 SC: Well, [chuckle] Sure, I do see the potential for that in the sense that I believe there is a potential... If I knew how to do it, I could be much more specific, but I don't. Okay, there was interestingly, very recently something I tweeted about a post on the blog Marginal Revolution, which is shared by Tyler Cowen, previous Mindscape guest, but his co-author, Alex Tabarua was the one who posted it, who was pointing to a new paper by McDonald and Shales, I believe is them, which basically took some of the most commonly accepted economic models, DSG-e... I'm gonna get it wrong. Dynamic General System equilibrium, some combination of those words. These Models that everyone uses, an economic is very, very popular, and roughly speaking, it is only a slight exaggeration to say that they said they are completely nonsense.

2:49:10.1 SC: And here is how they show that they are non-sense. They use the model... So what the model means is there are certain parameters, certain parameters for different economic things, this thing is producing this, there's a certain volatility over here, etcetera, and you can change the parameters and get different predictions for economic output, GDP, unemployment or whatever you wanna get... So parameters, the into predictions from these models, so basically they... But there's also randomness in them, so you don't predict a terminus Cally 'cause there's... You predict a probability distribution. They use the model to make a prediction to sort of predict a future history given some parameters, and then they took that history and they fed it back into the model and ask, Okay, what are the values of the parameters? And there was essentially no relationship between the values of the parameters that they derived and the ones they had put in. In fact, they said you could even change the labels on the variables, so what they called the inflation rate, they took the actual values of the inflation rate and switch them for the values of the unemployment rate, and the model found just as good a fit, even though that makes no sense whatsoever.

2:50:18.6 SC: I haven't read this paper, so I don't know whether they're right or they make some assumptions and they make some mistakes, they're good people, but it speaks to the difficulty of modeling and forecasting these complex social behaviors. I guess what I'm saying is, Yes, I think we can do better, but we're not doing very well right now. And that's okay. It's completely okay. Did not do very well right now, we're young and not very good at this yet, but we're learning, we're learning about the whole idea of something called a complex system, there are some regularities in Complex Systems, even if they're only statistical. I remain optimistic that we can do better. But it's hard and it's gonna take a long time.

2:51:02.3 SC: Jim Murphy says, I've developed a hobby of creating cellular automata and watching the emergent results of various rules."

2:51:09.3 SC: This is a good hobby. I wish more people had hobbies like this. What do you need to do, Jim, by the way, is convert it into a social hobby, somehow make a website, the crowd sources, cellular automata and see who's best at finding out the rules. Anyway, the question is, the vast majority of the rules seem to produce a chaotic static without any... I think is a typo here, chaotic situation without any obvious complexity emerging, however, I wonder how much this is a result of my limited computational power and world size versus the inherent properties of the automata. Do you have any intuition for how often rules that a peer chaotic at a small scale will create immersion complexity on a larger scale.

2:51:51.3 SC: I have an intuition, but I don't know whether my intuition is very good here, I do think the question is super-duper interesting. So for those of you who don't know, in the game of life, for example, this was invented by the mathematician, John Conway, famous checker board, kind of set up and you put some squares down and then let them evolve according to certain rules, and you can see patterns you can see things that look like gliders, and you can even see things that are what are called glider guns, they're like a fixed configuration that will spit out a series of gliders that move away, and you can even show that you can do calculations using this whole kind of set up. Similarly, Stephen Wolfram former Mindscape guest, needing to say, I was able to show that you could do similar things with one-dimensional cellular automata rather than two-dimensional ones.

2:52:41.3 SC: So there are these examples of emergence. Now, maybe Jim, you should actually look at Wolfram book on a new kind of science because he's kind of interested in this question. In the world of very, very simple one-dimensional cellular-automata, as long as you have the idea that three sites at one time step predict the one site below them, at the next time step, you can literally write down every possible rule. And then you can literally say, Here's the subset of rules that lead to emergent behavior, so you can count. But what you're asking is, how does that scale with more dimensions, more complexity, etcetera. My intuition is that even as things get bigger and higher computational power, it will still be generically not true, that you see simple emergent behavior. I think that most things will just be a chaotic mess. Depending on what you allow yourself to put in. So for our world, for our real world universe, we certainly have emergent behavior in the world, you and I are examples of emergent features, immersion systems. But that rely is kind of heavily on two things, Number one, there is a hierarchy of scales.

2:54:04.6 SC: So there are atoms that are made of different masses, there are particles are made of different masses, and crucially, there are photons, which have no mass at all. What this means is that the atoms and the electrons and so forth bumping into each other can dissipate by giving off photons, and it's not very easy to model that in a cellular automaton because you're keeping track of everything. What a astrophysicist do when they wanna think about the formation of a star, you don't keep track of every photon, the sun is, the star is giving off heat or whatever, and that's dissipation and that sort of brings you down into a sub-space of all the possible configurations and gives you a handle on what's going on and helps explain emergent phenomenon. So that's one thing. The hierarchy of scales.

2:54:55.0 SC: The other thing is, of course, the past hypothesis, the fact that we began a very, very, very special initial state and that allowed complexity to arise as I've talked about before along the way, and as I talk about in the big picture. So without those two very special features, I think that generically, you would not expect simple, coherent large-scale structures, but this is again, something I'm totally happy to be wrong about because I don't know of any systematic exploration of the space possibilities there.

2:55:30.2 SC: Okay, the final question is a long one. Terrible Turnip. Not the question, the AMA has been long. So... But I like it. I like doing these AMAs if I had more time, I would do them more, I do not have more time, I don't even have time to do this, but I'm glad I'm doing it. Terrible Turnip says, "What is your view on how specific a fundamental theory should be to feel right." It seems there is a paradox of sorts, if one finds a theory such that there is only one viable self-consistent possibility. That would seem very strange. On the other hand, if there are a huge range of possibilities that would seem to make people uncomfortable in that case, you would end up using anthropic principle-type arguments to justify one's observation of this particular universe. I don't think that it's a matter of feeling right in this sense. Some theories... There is something called feeling right, I get that you're on the right track there, but the feeling right has to do more with how simple and elegant the theory is, the ways in which you either directly or indirectly connected with observations, the scope and fruitfulness of the theory. The compatibility of the theory with other existing ideas that we think are true, things like that, that's what goes into making a theory feel right.

2:56:46.9 SC: You're focusing in on a very important idea, which is how accepting or not accepting the theory is of different kinds of solutions. If there's... We were talking about solving equations, if you have a set of equations where there's only one solution versus if you have a set of equations that had many, many solutions and both are perfectly plausible. I don't think that you should really judge the feel of theories along that particular dimension, I can't imagine a theory that only had one solution and also fit the data, but if you had it... If you had a theory that only had one solution and it was a perfectly good fit to the universe, I think people would be ecstatic about that, the fact that it can't fit other things that didn't happen should not count as a strike against it is what I would say. On the other hand, like you say, when there are a huge range of possibilities, you feel like it's almost a shame, someone like David Gross, famous String theorist, is very upfront about the fact that throughout his life, he has been hoping to find the one theory that uniquely predicted our world, that's why he's very sad at the current popularity of more anthropic explanations.

2:58:01.8 SC: I don't quite feel that way, I'm perfectly happy if the fundamental theory predicts a whole bunch of things and we are just a statistical prediction within it, maybe it would have been nicer to be more specific. But I always always say that we don't get to make demands of the universe and how it operates. I wanna figure out how the universe operates, I don't wanna tell it how to operate. The very, very good news is that the universe operates in such a way seemingly, that we can figure it out, and that's a non-trivial fact about the universe. With respect to Jim's question on the previous one, if the laws of physics have been different, maybe we would have no hope of figuring it out, but not only can we figure out something about the laws of the universe, but we can do it piecemeal, we can get better and better at it, we can get one regime under control and then get more and more, and that's just the best way, that's the most fruitful way to figure out these very, very deep, very, very wide-ranging principles that make the universe runs in all ways. I would say, count our blessings, that the universe is so nice to us to help us figure it out, and don't tell the universe what to do will be my advice.

2:59:10.7 SC: Alright, thanks everyone for hanging in there for the AMA. Happy beginning of fall... Like it's fall here in Baltimore. It's been a long time. So I lived in the northeast, I lived in a region of the country where they didn't really have seasons in any noticeable way, so it's very, very nice to see the beautiful colors of the trees and all that. And don't imagine that I don't know that the niceness will not last forever 'cause it's coming... There's gonna be winters. It already gets dark very early around here. So, Happy November. Happy Halloween, I guess, Halloween's already passed. Happy Thanksgiving, happy all the various holidays that happened between December and January. Talk to you soon.