While we’re getting the multiverse out of our system, let me point to this interview with Leonard Susskind by Amanda Gefter over at New Scientist (also noted at Not Even Wrong). I’ve talked with Amanda before, about testing general relativity among other things, and she was nice enough to forward the introduction to the interview, which appears in the print edition but was omitted online.
Ever since Albert Einstein wondered whether the world might have been different, physicists have been searching for a “theory of everything” to explain why the universe is exactly the way it is. But one of today’s leading candidates, string theory, is in trouble. A growing number of physicists claim it is ill-defined, based on crude assumptions and hasn’t got us any closer to a theory of everything. Something fundamental is missing, they say (see New Scientist, 10 December, p 5).
The main complaint is that rather than describing one universe, the theory describes some 10500, each with different kinds of particles, different constants of nature, even different laws of physics. But physicist Leonard Susskind, who invented string theory, sees this huge “landscape” of universes not as a problem, but as a solution.
If all these universes actually exist, forming a huge “multiverse,” then maybe physicists can explain the way things are after all. According to Susskind, the existence of a multiverse could answer the most perplexing question in physics: why the value of the cosmological constant, which describes how rapidly the expansion of the universe is accelerating, appears improbably fine-tuned to allow life to exist. A little bigger and the universe would have expanded too fast for galaxies to form; a little smaller and it would have collapsed into a black hole. With an infinite number of universes, says Susskind, there is bound to be one with a cosmological constant like ours.
The idea is controversial, because it changes how physics is done, and it means that the basic features of our universe are just a random luck of the draw. He explains to Amanda Gefter why he’s defending it, and why it’s a possibility we simply can’t ignore.
David says : That is merely opinion, not an incontrovertible fact. If there is no multiverse, then some may decide that Occam’s razor comes down in the favor of design rather than blind luck. In that, Susskind is correct.
Sure. But
(a) I don’t think the fat lady has given up yet.
(b) Would you advocate the teaching of “Blind Luck Decides that We can Exist in this Universe” in public school science classes? (Since, as you said, both are merely opinion?)
Who,
I have scanned the paper and it looks very interesting. I will take some time to read it carefully.
Eugene,
No. If the topic of fine-tuning came up in a tangential discussion (since it is not going to be in the curriculum) I would advocate teaching that the competing explanations, all (in the Popper sense) unfalsiable (in my opinion, I am will to convinced otherwise) are multiverses, design, and blind luck. After that, there isn’t much to say.
Just read an interesting challenge to ID. That is if you take ID as true then you most certainly would need to ask who made the designer. It would obviously need to be an even more intelligent designer. This lead to an infinite series of intelligent designers each a bit more intelligent than the previous one. Seems like a bit of a logical cul-de-sac to me.
Elliot
Elliot,
I assume you are very young or just starting to think about ID, because “who designed the designer” is the oldest, the most repeated, and probably the weakest criticism of ID. It is also probably the most easily handled criticism of ID. It is roughly akin to criticizing evolution by asking “what good is half an eye?”
David,
I don’t see the analogy to asking what good is half an eye. It is strained at best.
Since it is the oldest and most oft repeated, I imagine it has some creedence.
I am not young but you are right I haven’t spent much time thinking about ID. Given that it is basically creationism with a new brand name not sure I need to.
Elliot
Dear David,
regarding this
you say
thanks for expressing interest. I hope you do respond at more length. If you respond in your blog please call my attention to your reply in this thread so I don’t have to watch two places.
the CNS explanation of the constants is FALSIFIABLE, which is the whole point. The falsifiability claim is something you should check to see if you find it convincing because the falsifiability responds to what you say here:
If indeed you are WILLING TO BE CONVINCED, as you say, that one of the competing explanations is falsifiable, then here it is. Please consider, not whether you like the theory (I am not advocating it) but whether you agree that it is falsifiable.
CNS presents you with the following challenge: look at the list of fundamental dimensionless constants and find even one in which a small change would promote the formation of more stellar-mass black holes.
Very simply, the CNS explanation for the basic constants is that they are approximately optimized for black hole production. They may INCIDENTALLY favor life as we know it but this is a side effect. What the constants really favor is black holes.
Details can be found in the paper I mentioned and references therein.
It seems clear to me that the conjecture that the basic constants are a local maximum for black hole formation is falsifiable. All you have to do is find one constant (like a quark mass) which, if changed, would yield a significant improvement in the rate of black hole formation.
If the constants turn out to be fine-tuned for black hole abundance, that provides for a simple explanation as follows:
Several of the papers at the October Loops ’05—an international quantum gravity conference—were about the emergence of big bangs from black hole gravitational collapse. Quantizing removes the singularity and the collapse at the pit of a hole has to go somewhere and it now looks as if spacetime may continue on out in a bounce, and re-expand. In other words stellar-mass black holes produce other branches of spacetime. The relevant quantum gravity theory predicts signature that can be looked for in Gammaray Bursts. Parampreet Singh at Penn State gave a talk about that in November, which fortunately is online.
So black hole formation provides a possible reproductive and hence evolutionary mechanism by which a set of fundamental dimensionless constants, like a set of genes can evolve.
This evolutionary CNS theory does not say anything concerning the existence or nonexistence of a Divine Creator—-it simply offers a mechanism by which the basic parameters are self-tuning.
there might or might not be some Creator somwhere who set the whole tree-like branching process in motion—-many black holes ago, many iterations, many bounces, many big bangs ago.
But that imagined Creator, if existent, would not have needed to twiddle the knobs in order to fine-tune the basic constants of our particular spacetime branch
The fine tuning is taken care of by Smolin’s proposed cosmological natural selection process. Which, it is argued, is FALSIFIABLE. That is why it is a significant part of the discussion and why I suggested the paper to you.
Cheers,
Who
Given that it is basically creationism with a new brand name not sure I need to.
I agree Elliot. I am hoping that I am speaking for a part of society, and if not, apologize for “imposing my thinking on them,” if it felt this way. If one did not speak about this, would the “battle not have taken it’s toll” without them knowing the results they are dealing?
Is this what those who Fight against ID are trying to do?
Who knows. Maybe a stronger resolve for “empowerment” shall arise out of the chaos, once a resolve is held too?
Re: CNS,
Are there variants of this theory which postulate other selection mechanisms than black hole formation? Certainly it is an interesting one but not the only thing that could be selected for that would potentially lead to the emergence of intelligent life in this or any other universe.
Elliot
Who:
I think this is a reasonable assessment( my struggle to geometrical propensities in regards to quantum geometries?) in expression.
Would this contradict Multiverse idealizations or demonstrate compatibility?
Elliot, to reply to your question
the answer is almost no other but I seem to recall a paper from the mid 1990s which proposed a variation of Smolin’s CNS. It may have been by Louis Kauffman. Maybe I can find it on arxiv.
to make the obvious point, black hole formation provides a credible reproduction mechanism: in the past year a fair number of Quantum Gravity papers have been written about gravitational collapse and they mostly point towards a bounce, in which spacetime continues and reexapands in a new branch from the pit of a black hole—inflation providing a fresh endowment of matter.
admittedly intelligent critters could INTERFERE and perhaps encourage black hole formation, so there could be some extra reproductive fitness associated with branches of spacetime where there were creatures willing and able to do this (so their branch or universe would pass on its characteristics to more offspring branches).
It is a thought but for me seems just unnecessary complication. the main issue is whether the universe is optimized for black hole abundance or not. it is something that ought to be able to be settled by observation, as long as the fundamental constants of physics (as they effect star, galaxy, and black hole formation) are well understood
Elliot, that mid 1990s paper was by Louis Crane (not Louis Kauffman) and it was
http://arxiv.org/abs/hep-th/9402104
more discussion of the CNS idea, including criticism and possible variants, is in this paper of Rudiger Vaas
http://arxiv.org/abs/gr-qc/0205119
Who,
Thank you very much for your response and the references. The Crane paper looks particularly interesting.
Elliot