Greetings from Norway, where we’re about to embark on what is surely the most logistically elaborate conference I’ve ever attended. Setting Time Aright starts here in Norway, where we hop on a boat and cross the North Sea to Copenhagen. The get-together is sponsored by the Foundational Questions Institute, although it came together in an unusual way; I was part of a group that was organizing a conference, and we applied to FQXi for funding, at which point they mentioned they were planning almost exactly the same conference at the same time. So we joined forces, and here we are. Unity ’11!
The topic, if you haven’t guessed, is time. That’s a big subject, one that can hardly be done justice by sprawling books with hundreds of (admittedly quite charming) footnotes. You can see why the conference has to spread over two countries. We’re trying an experiment in interdisciplinarity: while the conference is a serious event meant for researchers, we have a wide variety of specialties represented, including biologists, computer scientists, philosophers, and neuroscientists, as well as the inevitable physicists and cosmologists. (There is also a public event, for those of you who find yourselves in Copenhagen next week.) I can’t wait to hear some of these talks, it should be a blast.
My job is to open the conference with an introductory talk that hits on some of the big questions. Here are the slides, at least as they are right now; last-minute editing is always a possibility. I think I put enough in there to provoke almost everyone at the conference one way or another.
@Alan (#7) : Does the multiverse “select out” self-sustaining universes? ..
That’s an interesting idea, which might fit well with my notion of each universe (lowercase – meaning a causally connected chunk of the Universe AKA multiverse) comprising the constantly evolving combination of “neighbouring” parallel universes immensely speeded up, a sort of composite of ever-changing tangential possibilities.
I’ll paste a post of mine in a recent a many-worlds discussion in another forum.
> aren’t the scientific multiverse theories a bit less vague than that, in that they DO
> posit some kind of relationship between universes as a way to explain how ours works? ..
No, that’s the problem. Conventional parallel universe interpretations posit no influence of one on any others, which means the theory is impossible to test directly.
I reckon the opposite is true, but each universe evolves to completion in the other in the shortest possible time (in fact defines a Planck time unit), where “completion” here means either expand to infinity or collapse.
So we, and everything we experience, in other words all fields and particles, are nothing _but_ parallel universes constantly being created and destroyed, with each “split” representing a choice at the most fundamental level (individual energy quanta) between two possibilities.
Evolving so fast, for all practical purposes the parallel universes are late stage ones, comprising nothing but vacuum, as ours will one day in something like 10^500 years once all the black holes have evaporated.
Note that in theory if you fell into a large rotating black hole then as you approach the inner horizon, the outside universe you had left behind would appear to evolve ever faster until it evolved to completion in a tremendous blue flash. So that illustrates in a crude way that universes can manifest themselves enormously speeded up in others!
One can sort of see how this might conserve energy in normal circs, but at the same time allow for mysterious effects that apparently don’t, such as dark energy or the Big Bang.
It also seems vaguely plausible that limiting splitting to an unambiguous situation, where say there are only two possibilities, might ultimately be what allows energy to collect in and preserve the resonant states we call particles (and determine their relative masses etc).
But without being able to whump up some formal model consistent with conventional QM and GR, it’s just a lot of vague musing and most physicists would (rightly) not give the idea the time of day.
End of paste
The only snag with relating this idea with selection of long-lived universes is that as I have explained the parallel universes splitting from another must time-wise be very localized in the latter, as much so as can be. So it’s hard to see how collectively they could impart a long term property to the universe from which they split.
I’m only 4 hours from Bergen, I’d ran into you if I had known.
As T->0 K, the entropy goes to zero.
The universe started at zero entropy
So was the temperature at the moment of the big bang absolute zero?
I think that was my Boltzmann Brain popping into existence.
“while the conference is a serious event meant for researchers, we have a wide variety of specialties represented, including biologists, computer scientists, philosophers, and neuroscientists, as well as the inevitable physicists and cosmologists.”
hahaha
It seems to me that this medium entropy — high complexity connection is a similar conundrum to the fine-tuning problem associated with the matter-dominated universe. On a logarithmic scale, the universe is matter dominated for only a few orders of magnitude in scale factor while deSitter space is infinte in extent during lambda-domination or past-eternal inflation and even the radiation-domination phase spans far more decades in time than matter-domination. And yet we live within an order of magnitue of this particularly unique time in our universe’s history. What gives? And why is there so much medium entropy right now?
I cannot find a video or recording of Severn Darden’s metaphysics lecture, so this transcript will have to do:
http://groups.google.com/group/rec.music.dementia/browse_thread/thread/86f5c66980d81fa3
I am not a physicist (inevitable or otherwise), but it seems to me that the questions of time all amount wholly to perception issues given that the laws of physics have no requirement of running one direction or another — or in any sort of “direction” at all. Thus, changes in relative entropy, while certainly interesting, can’t really be used to address the time question at all because they are not necessarily synchronized with perceptions — even if they may seem to be.
Simply said, there is no reason to believe that humans would perceive the arrow of time any differently if there were no correlation with changes in entropy (or any other external condition, for that matter). But there are clear indications that the problem has more to do with the design of the human (and the view of time provided by the senses, processed by a brain) than it does the design of the universe.
I realize that this may sound like an application of the anthropic principle, but I don’t exactly intend it that way.
In physical space we are limited to a certain point of view based on location. This is inherent in the design of our senses. We can conceive of different points of view (say the view of the universe from the Andromeda galaxy) but we have no way of actually experiencing it (though that could be theoretically overcome).
Likewise, why could we not be limited to a certain point of view in time based on our design? We can conceive of different points of view in time (namely, remembering the future and predicting the past), but have no way of actually experiencing it (though perhaps that could be overcome).
The direction we face in time, just like the point of view we’ve been given in physical space, could be completely arbitrary, requiring no further explanation.
(I’ll admit that this is not wholly satisfying.)
A Predictive Interlude
Hmm, lots of general discussion of highly unprovable things. So just for grins, here’s a specific prediction I’ve been making to friends for about three years now. I know it seems unrelated to time, yet there are connections.
Firstly though: I am poor, simple computer person, and emphatically not a trained physicist. So folks, this really is just for fun, an example of using heuristics and complexity reduction techniques to search for interesting postulates within intentionally minimized mathematical and topological frameworks. With that said, here’s my postulate:
There is no Higgs boson — not at any energy, not at any level of data analysis. The particle simply does not exist. While the real mass mechanism has certain similarities to the Higgs premise, it is not created by the Higgs field for the simple reason that no such field exists. Mass derives instead from a different and rather simpler form of stickiness.
My no-Higgs postulate can be generalized in the following way: There exist no fundamental (i.e. point-like and non-composite) spin-zero particles of any type. Such particles simply cannot can exist within the spacetime of our universe.
Given the recent spate of anti-findings of Higgs analysis coming out of the LHC, this likely doesn’t count as much of a prediction, at least not now. Still, a lot of people have not quite given up on Higgs yet, so perhaps it’s still timely. And in any case, my prediction that there are no fundamental zero-spin particles is a bit broader than just saying “no Higgs.”
That’s a pretty brave opening talk, but seems mostly reasonable, I hope you got some useful feedback.
As #8, I’m also somewhat confused as to the notion of ‘complexity’ employed. Generally, if we’re looking at the microscopics, the Kolmogorov complexity of the last shot glass should be highest — since it’s essentially a random string of ‘molecule of white liquid, molecule of black liquid’, etc. True, on the macroscopic level, a short description, and hence, low Kolmogorov complexity appears possible — something like ‘all brown’, for instance.
But then, entropy is consistently measured against the microscopic level (as it must be). If we do the same thing wrt Kolmogorov complexity, it exhibits the same kind of behaviour: the shot glass with white and black substances separated will admit a heavily compressed description (writing 0 for ‘molecule of black liquid’ and 1 for ‘molecule of white liquid’, we get something like 111111…00000…, which is evidently highly compressible), the middle phase of partial mixing is still somewhat compressible, while the final, mixed state, equivalent to a random bitstring, will be almost totally incompressible, and thus, of maximum complexity.
Otherwise, just looking at the macroscopic level, one could argue that there is one state for ‘black and white separated, white above black’, a number of states for ‘black and white partially mixed’, and just one state again for ‘all mixed’, or ‘all brown’, giving the impression that entropy decreases!
complexity isn’t the same as randomness at microscopic level, the mandlebrot set has a very simple description mathematically but you couldn’t so well compress samples of the set at high resolutions.
Similarly the heat death of the universe or the completely mixed liquids have a simple description (start from unmixed and mix until no further change (on some coarse scale) (ignore poincare recurrence)), but the intermediate stages have no such simple description, they are highly “complex”
“An individual respective very location is the present and rest all locations are of the deep of the past”. That is to say- Our home planet is present before us, likewise just at this time it is again submerged into the depth or the past from another place of space. In the universe, there has been no incidence of present and future at all at any site of space, all are submerged into their respective depths of the past. In or under the circumstances: See into- Amazing facts about the Universe at http://t.co/a8LHwAY
I have a couple of questions about Sean’s birthday photo example in ch. 9 of From Eternity to Here (granted this isn’t exactly on point with this thread, but I missed the interactive book club and I couldn’t think of a better place to possibly get a useful response). I teach physics at a school for gifted children and thought it would be fun to go over some of these ideas with my students when we get to thermodynamics, but I would like a better understanding of a few things first.
The entropy increasing in both directions of time from a point of low entropy makes perfect sense to me, but the fact that the random apparition of a photo of you in a red shirt is a higher entropy state than the string of events that we would normally think of as leading to such a photo does not seem so evident. The fact that the photo would have to corroborate with so many things (possibly other people in the photo, other objects in your house, as well as your memories of the party) makes it seem even less probable than the universe producing an actual party. Maybe a photo of a stranger in an unfamiliar location would avoid these problems, or is there something I’m missing?
A second question is actually of more interest to me. Granting that the spontaneous photo is indeed higher entropy than the event actually having taken place, I’m still having a hard time seeing how the Past Hypothesis gives a preference for lower entropy events in the past. Where I get caught up is when switching from looking at the entropy of the universe to looking at the likelihood of entropy states within a portion of the universe. Surely the PH excludes past higher entropy states for the entire universe, but does that make lower entropy states of a given sub-system of the universe more likely than high entropy states (i.e. the actual event over the random photo)? Would this depend on how far from equilibrium a low entropy state of the universe was (e.g. extremely low entropy states of the universe might make high entropy states of a sub-system unlikely, but entropy states of the universe near yet still below equilibrium would have sub-systems that favor high entropy states)?
Any thoughts would be appreciated.
Came across this:http://www.youtube.com/watch?v=Lvx945SP-RM&feature=player_embedded
when someone posted the standard time dilation and simultaneity objection to the questioning of the existence of time. Unfortunately I am only coming at it from a lay-persons perspective so cannot really critique it, or challenge it, but it makes some interesting points which appear to be quite logical and are allegedly backed up with reproducible experiments.
It attempts to highlight flaws in the thought experiment Einstein used, suggesting that there are flaws in the models which, when accounted for, would lead both the observer on the train and on the platform to conclude that the flashes of lighning occured simultaneously.
Here is the website: http://absolute-relativity.be/node/7
This potentially addresses the issue of simultaneity and time dilation as mentioned above, although I am not in a position to say whether it definitively does or not. It is, however, incidental to the argument that time does not exist.
just on the above, the standard time dilation and simultaneity objection was not the one posted here, but in a message board – it was accompanied by a video explaining time dilation and simultaneity
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Time does not exist. It only exists to entities that are born in one “moment” and dead in another “moment”. Take away birth and death from the scene…and there is nothing called Time. Humans never measure anything that they have an infinite supply of (again infinity defined by what they perceive to be not finite per their senses). Anything they find finite ..as perceived by their senses…..will be measured…be it Time(bound by the finiteness of mans birth and death..) or Temperature ( bound by the finiteness of what s/he percieves to be “hot” or “cold”)
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> “A Lifespan is a Billion Heartbeats”
Only partly correct, according to an ancient essay by Issac Asimov.
Briefly, he observed that for all mammals except humans, their lifespan is around 1 billion heartbeats. He analysis relied on a table of metabolic rates (expressed as pulse rate) multiplied by maximum lifespan for each species. Shrews have a pulse of about 3000 beats per minute, but only live about 3 years. He discovered that body mass is proportional to life span, and body mass is inversely proportional to pulse rate.
Except for humans.
Taking 60 bpm as a typical pulse rate, and 115 years as maximum known life span, we live up to 4.5 billion heartbeats.
(Ignore the bleatings from religiouis types, shrieking, “Abraham lived to 900 years!” Piffle. Twaddle. Horse-feathers. Bicycling fish.)
At age 50, I’m already past 1.5 billion heartbeats: 1,576,800,000 (according to MS Calc).
My maternal grandmother lived to 102 years, 3.2 billion heartbeats.
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