Smolin: Anthropery is not science

[Ontoplankton]

The point about the scientific community is they can get agreement by empirical tests.

they arent like theologians who split up into various parties and sects and schools of thought

The universe does not care about how we think social communities should work. It is under no obligation to provide us with ways to prove or disprove everything we would like to. If the most fundamental theory is one that makes no very specific predictions on what we will find (other than that we'll find a universe consistent with the existence of observers), then this is simply something we will have to accept. Anything else is just wishful thinking.

Of course, maybe this theory is wrong. If Smolin's black hole theory predicts specific things that the anthropic principle doesn't, then that counts in favor of it; but there are many things to take into account (such as: how plausible is his mechanism that generates a universe slightly different from ours? how strong is the evidence for eternal inflation?), and I have no way to judge all of these. Maybe Smolin's theory and the mono-vacuum versions of string theory will be falsified in the future; maybe in the future, the eternal-inflation-plus-anthropic-principle theory will the only one that predicts a universe with observers at all. In that case, we should accept it until we do find something better, and in the mean time, it should be taken seriously as a possibility.

But Onto, you have not yet exhibited anything weird about what Smolin says!

I exhibited a few weirdnesses in my first post in this thread.

I'm finding it difficult to criticize specific claims by Smolin, because I don't agree with the Popperian framework he places everything in. In fact, I can feel my brain shrinking as I think about falsificationism, right at this moment!

It's true that the anthropic scenario isn't falsifiable, but that doesn't mean it isn't testable in a more general sense. Any time a different theory predicts something specific about the universe not already implied by the existence of observers, that counts against the anthropic scenario; it makes it less plausible, just not impossible. Any theory that's consistent with any possible observation is unfalsifiable; there are more of such theories than you would expect. Smolin's black hole theory is one of them, because it has a varied multiverse where each universe has different laws. The difference between Smolin's theory and the anthropic scenario is that in Smolin's theory the worlds whose laws and constants are such that they don't allow for observers are "very rare" (though there are infinitely many of them!), rather than "common but empty anyway". I'm not sure that this should matter.

Anyway: IIRC Smolin calls his theory "falsifiable" even though it only makes probabilistic predictions (it's logically consistent with all sorts of physics, but some sorts of physics are more common because they produce more black holes), and at the same time calls the anthropic scenario "unfalsifiable" because it only makes probabilistic predictions (it's logically consistent with all sorts of physics, but some sorts of physics are more "typical" of the kind you would expect to see as an observer). The way to deal with probabilistic predictions is Bayesian probability theory. There are very difficult issues in how to deal with observational selection effects and with infinities in a Bayesian framework, but they're not the difficulties that Smolin talks about.

There's a whole literature on all this stuff, and it looks to me like Smolin hasn't read it.



IMHO, it all depends on whether Smolin's black hole claims hold up under further tests, and on how much more (or less) specific the region (in law-space) of black-hole-maximizing universes turns out to be compared to the region of observer-generating universes. It looks to me like Smolin may have a case for his theory, but his grounds for rejecting the alternative completely are wrong.

 

[jeff]

The Anthropic Principle = "Sorry, but we're kinda stuck for good ideas at the moment. Please check back later. Thanks."

 

[marcus]

The Anthropic Principle = "Sorry, but we're kinda stuck for good ideas at the moment. Please check back later. Thanks."

I agree with jeff.

 

[sol2]

The Anthropic Issue and the Flower Scheme

So who has last word?

Lubos said,

We have discussed these questions a lot on this board. If the number of
possibilities to create a Universe - including working cosmology - in the
correct theory *is* that huge, we will have to live with this fact. String
theorists don't agree yet whether the usage of the Anthropic Reasoning
will be necessary. Many of us hate it. But it is a logical possibility. At
any rate, as long as theoretical physics exists as a field, the scholars
in it will study something. Because they have no new experiments, they
must study more or less pure theory. String theory remains the most
promising game in town, perhaps the only game in town. This might
hypothetically change - but only if someone found something equally (or
more) interesting. It cannot change by political speaches without
scientific content, even if the speaker is as famous as Roger Penrose.

https://www.physicsforums.com/showthread.php?p=271882#post271882

So you can see, you have to be smarter then Edward Witten, and apparently you Marcus and Jeff are not. Cheez, that Lubos guy is sure not very nice. He think's he's tuff guy

Most string theorists are also too
nice - perhaps except for me- and therefore they won't comment on
declines of Roger Penrose although there would certainly be a lot of stuff
to discuss.

http://web.uvic.ca/~jtwong/T-Huniverse.jpg

I think the issue has become somewhat confusing when you think the universe came from a pea So where did the Pea come from?

And then he has the nerve to comment on the GRanium and Daisey's as Tulips! Not very original I think although they do belong to the class of the flower children. Maybe we can work the image of the tulip into Hawking's as a good visualization of the Instanton? Or even the lotus flower, as a symbol of the "emergent realites," deep from our subconscious level

> String theory has had a kind of tulip-mania fad or craze and now seems
> to be in decline.

Well, we've heard such things since the middle 1980s at least. It is
certainly a longer-lasting fad than any other fad in the history of
humankind. ;-)LM

Let's heard from you now Lubos-the tuff guy. I know thorny Jeff(the rose) can give you a run for your money


So now being lead into this fantasy:

Sol said:Would twenty mattresses help Alice, and how complex can each mattress remove the thinking from the pea of concern

http://superstringtheory.com/forum/dualboard/messages11/44.html

Fictional Alice was a http://superstringtheory.com/forum/dualboard/messages11/100.html :) Mathematicians tire easily becoming lost in the abstract theoretical world, so often times like Lewis Carroll, they create this new found fantasy to help see the world in a different way? Break the bonds of abstractness, and loose themselves in this world of fantasy.

What you don't like Penroses tessellations or Escher's interconnecting lizards?

During the later half of the 1950’s, Maurits Cornelius Escher received a letter from Lionel and Roger Penrose. This letter consisted of a report by the father and son team that focused on impossible figures. By this time, Escher had begun exploring impossible worlds. He had recently produced the lithograph Belvedere based on the “rib-cube,” an impossible cuboid named by Escher (Teuber 161). However, the letter by the Penroses, which would later appear in the British Journal of Psychology, enlightened Escher to two new impossible objects; the Penrose triangle and the Penrose stairs. With these figures, Escher went on to create further impossible worlds that break the laws of three-dimensional space, mystify one’s mind, and give a window to the artist heart.

In order to understand how Escher used impossible figures to create impossible worlds, impossible figures must be clearly defined. In his article Escher’s Impossible Figure Prints in a New Context, Ernst Bruno gives a thorough description of the thought process one goes through upon seeing an impossible figure. Bruno’s account can be summed up to produce a concise definition of an impossible figure; a definite figure with conflicting depth cues.

http://www2.bc.edu/~schiavop/escher.html

 

[marcus]

Hi Sol, tho often perceptive you may have a misconception here. If you could get Witten and Motl and Smolin to sit down just to talk about the effect on String theory research
of Susskind invoking multiple universes and resorting to athropery

(not to quarrel about other issues or discuss the merits of Loop or anything else, but just to assess whether AP has had a good effect)

what do you think? I don't want to put words in their mouths, but I think you should realize that they might agree in condemning Susskind's line and the AP, or deploring it's taking String theory in an unscientific direction.

Witten has expressed disapproval of resorting to AP
Motl (who may tend to follow Witten's lead in some matters) has
strongly condemned AP
Incidentally Jeff (who may tend to follow Motl's lead on key issues, or have come to similar positions independently) is here in solidarity with Witten and Motl.
Incidentally BTW (tho small fry outsider to string) I am in agreement with these people----Susskind's noisy invocation of AP, which has damaged the perceived integrity of String research, is causing distraction and a waste of intellectual resources.
Smolin would agree I believe.

Your post seems to suggest (if I read your symbolic and ornamented language correctly---which can be both a challenge and a pleasure)
that you expect disagreement and see a possibility for debate.

Of course I can't speak definitely for Jeff or any of those others but I strongly suspect that if you could get Witten, Motl and Smolin to discuss just that one issue they would be in hearty agreement-----contrary to what you seem to expect.

Let's not manufacture disagreement where there is none, sol

 

[sol2]

Hi Sol, tho often perceptive you may have a misconception here. If you could get Witten and Motl and Smolin to sit down just to talk about the effect on String theory research
of Susskind invoking multiple universes and resorting to athropery

(not to quarrel about other issues or discuss the merits of Loop or anything else, but just to assess whether AP has had a good effect)

what do you think? I don't want to put words in their mouths, but I think you should realize that they might agree in condemning Susskind's line and the AP, or deploring it's taking String theory in an unscientific direction.

Witten has expressed disapproval of resorting to AP
Motl (who may tend to follow Witten's lead in some matters) has
strongly condemned AP
Incidentally Jeff (who may tend to follow Motl's lead on key issues, or have come to similar positions independently) is here in solidarity with Witten and Motl.
Incidentally BTW (tho small fry outsider to string) I am in agreement with these people----Susskind's noisy invocation of AP, which has damaged the perceived integrity of String research, is causing distraction and a waste of intellectual resources.
Smolin would agree I believe.

Your post seems to suggest (if I read your symbolic and ornamented language correctly---which can be both a challenge and a pleasure)
that you expect disagreement and see a possibility for debate.

Of course I can't speak definitely for Jeff or any of those others but I strongly suspect that if you could get Witten, Motl and Smolin to discuss just that one issue they would be in hearty agreement-----contrary to what you seem to expect.

Let's not manufacture disagreement where there is none, sol

Marcus,

I like to create some humour as well and it should be taken in that context.

Do you really think I think any of these guys as tuff? I am challenging the group(flower children) per say that it has all been said and done. Do you really think they could sit down and agree? I know what they choose to believe

I also am speaking to Lubos on his position with Penrose. Imagine those math minds:)

 

[Ontoplankton]

If you could get Witten and Motl and Smolin to sit down just to talk about the effect on String theory research
of Susskind invoking multiple universes and resorting to athropery

I don't think physicists should be going down the path of "you must not think or talk about that, because it would be harmful to our cause". I prefer if they just tell me what they think are the most likely possibilities for what reality is like, rather than worry about taboos. If people like Gross and Witten and Smolin think no anthropic explanation will be needed, that's great. If people like Susskind think string theory leads to an anthropic scenario, that's also great.

 

[jeff]

What started this whole thing was the astonishing discovery that, contrary to all previous thinking, our universe is undergoing accelerated expansion.

This can be considered in the framework of GR as indicating something like a de sitter cosmology. However, the moduli space of string vacua don't include spatially compact cosmologies (consistent with the basic holographic nature of any correct theory of quantum gravity, the only true observable is the S-matrix whose inputs and outputs lie at spatial infinity and there's no such thing in spatially compact cosmologies). There are then two ways to look at this.

One is that we have to somehow find a way of bringing de sitter into strings and it was this attitude that led to the current debate. Specifically, they looked for metastable (that is stable for long periods of time) de sitter spacetime among all vacua, not just string vacua, with the very justifiable belief that string theory would still have relevance in such situations. Unfortunately, they found many such vacua but with no closed mathematical-physical principle to choose among them. Hence the invocation of the anthropic principle. Of course, it's possible that there is a way to sneak de sitter into string theory, but we just don't yet know how.

The other way to look at it is that the accelerating expansion is due to something that we don't yet understand and doesn't require de sitter.

The question is then whether we understand strings well enough to settle for the anthropic principle, and the answer is clearly no. From this standpoint, it's premature to be worrying too much about the anthropic principle. More generally, our understanding of strings is so primitive that we can't honestly conclude that any of it's current problems are fatal. Striking oil often requires we drill mighty deep holes and we've got a whole lot more drilling to do before we can give up on what has proven to be such a rich and self-consistent well-spring of deep ideas that is still our only known genuine quantum theory of gravity.

 

[selfAdjoint]

This was a very informative contribution. Thanks Jeff. I had wondered why the multiple solutions probloem, which I remember being discussed several years ago, had suddenly become such a hot topic.

 

[setAI]

more lenny vs lee action!


http://www.edge.org/3rd_culture/smolin_susskind04/smolin_susskind.html

 

[marcus]

more lenny vs lee action!


http://www.edge.org/3rd_culture/smolin_susskind04/smolin_susskind.html

setAI thanks for posting this!
a big reason I (and I would guess others) come to PF is to
get links to new really interesting stuff.

Smolin said something new in the final letter section, that caught my attention.
He referred to what I think is an important paper of Gambini Porto Pullin
about how using a realistic clock (instead of a nonexistent ideal clock)
can resolve the black hole information paradox.
(information decoheres by itself before the hole evaporates)

the two final letters start 2/5 of the way down the page, printed side by side in parallel columns.

If you go down to the 2/3 mark of the page----a ways down in the
final letters----and look in Smolin's column you will see this paragraph:

---quote---
"A second point is that there is good reason to believe that in quantum gravity information accessible to local observers decoheres in any case, because of the lack of an ideal clock. In particle physics time is treated in an ideal manner and the clock is assumed to be outside of the quantum system studied. But when we apply quantum physics to the universe as a whole we cannot assume this: the clock must be part of the system studied. As pointed out independently by Milburn [e] and by Gambini, Porto and Pullin [f], this has consequences for the issue of loss of information. The reason is that quantum mechanical uncertainties come into the reading of the clock — so we cannot know exactly how much physical time is associated with the motion of the clock's hands. So if we ask what the quantum state is when the clock reads a certain time, there will be additional statistical uncertainties which grow with time. (In spite of this, energy and probability are both conserved.) But, as shown by Gambini, Porto and Pullin, even using the best possible clock, these uncertainties will dominate over any loss of information trapped in a black hole. This means that even if information is lost in black hole evaporation, no one could do an experiment with a real physical clock that could show it."
---endquote---

where you see footnote reference [f] that is to this neat paper.
It came out in June before the big fuss over Hawking GR17 talk in July.
In my view it probably made the hooraw about Hawking superfluous.
I am glad Smolin is recognizing and citing this work. Jorge Pullin
occasionally visits here at PF and also puts out Matters of Gravity newsletter. I should get a link or two

 

[sol2]

I read this first thing this morning when reading in sci.physics the link (Should of read Peter Woits, Not Even Wrong Blog. Sorry Peter.

What I took with me from that article is the perception that is embedded in the debate about black holes.

That raises the question of what exactly is a black hole? One of the deepest lessons that we have learned over the past decade is that there is no fundamental difference between elementary particles and black holes. As repeatedly emphasized by 't Hooft [10][11][12], black holes are the natural extension of the elementary particle spectrum. This is especially clear in string theory where black holes are simply highly excited string states. Does that mean that we should count every particle as a black hole?

Smolin's theory requires not only that black hole singularities bounce but that the parameters such as the cosmological constant suffer only very small changes at the bounce. This I find not credible for a number of reasons. The discretuum of string theory does indeed allow a very dense spectrum of cosmological constants but neighboring vacua on the landscape do not generally have close values of the vacuum energy. A valley is typically surrounded by high mountains, and neighboring valleys are not expected to have similar energies.

http://www.edge.org/3rd_culture/smolin_susskind04/smolin_susskind.html

The word Susskind uses as discretuum(in bold) in regards to strings is most troubling. Maybe someone can speak to that?


Can Consciousness be truly expressed in the geometrical design( this has yet to be discerned), although I have been working on it as you can tell in liminocentric structures.


This might be found different from Smolins, based on their diffrent views and the different in the choice of geometry? The SRian approach and revisions?

You cannot speak about the background dependence unless you are immersed in it? And of course this requires a different frame? See http://wc0.worldcrossing.com/WebX?14@84.f0BIcWLAyal.19@.1ddf4a5f/99 for consideration about those frames?

 

[Ontoplankton]

Now http://www.edge.org/discourse/anthropic.html#myhrvold weighs in with yet another confused piece on the anthropic principle. His definitions of the "weak anthropic principle" and "strong anthropic principle" are around the tenth completely different variant that I've seen.

He questions "what value there is in not being surprised", but isn't the whole point to have theories under which our observations are unsurprising -- isn't that what an explanation is?

 

[marcus]

another word for it

Tom Banks has just posted 0408260
the first lines of the introduction go:


"Introduction
The hypothesis of Cosmological SUSY Breaking[1] (CSB) correlates the gravitino mass, m_3/2 with the cosmological constant, according to the formula

F_G \sim m_{3/2}M_P \sim \Lambda^{1/4}M_P . (1.1)

Lambda is viewed as a discrete, tunable parameter (perhaps determined in the real world by galactothropic considerations), and the limiting model with vanishing Lambda is assumed to preserve exact N = 1, d = 4 super-Poincare invariance and..."

then again on page 3 he goes:

"...This gives rise to a gravitino mass of order 10^-3 eV. The formula for the mass scales with the power of Lambda predicted in [2]. The value of w(0), which is a number of order 1, must be fine tuned to an accuracy
\inline{\frac{\Lambda^{1/2}}{M_P^2}} in order to produce the correct value, Lambda, for the value of the effective potential at its minimum. Lambda is a fundamental input parameter in CSB, rather than a calculable low energy effective parameter, so this fine tuning is philosophically unexceptional. If one wishes, one can determine the correct value of this parameter in the real world, by applying the galactothropic principle of Weinberg[5], rather than simply fitting more recent cosmological data..."

Lot of stuff going down around Lambda these days. For Smolin it seems to be a kind of pre-stressed curvature in space and a fundamental constant that applies to LQG, mond, etc.
for Banks it seems to be the "gravitino" mass
Banks does seem to respect Smolin's point that what Weinberg did was NOT
an application of the anthopic principle because it derives constraints on the value of Lambda by theorizing about galaxy-formation.
Nothing said about multiple universes or conscious life or all that jazz.
Just that whatever it is Lambda couldn't be too big or it would blow galaxies apart before they could form. So you could estimate an upper bound on it, from existence of galaxies.
Smolin made that point in "Scientific Alternatives to the Anthropic Principle"
the paper that yanked Leonard Susskind's chain to a considerable degree.
So now, for whatever reason, Tom Banks has the consideration to
call Weinberg's reasoning galactothropic rather than anthropic.
Clearly an idea whose time has come

 

[Ontoplankton]

This is why people distinguish between the "weak anthropic principle" and the "strong anthropic principle". The weak anthropic principle says that since we exist (or: since galaxies exist), we should predict the value of the cosmological constant isn't too far from zero. Whether we should call this "anthropic" at all is a question of terminology; maybe we shouldn't, because we're reasoning from the existence of galaxies, not from the existence of humans.

So far, so good. But there also exists a strong anthropic principle. The strong anthropic principle says that the fact that a sufficiently low cosmological constant is necessary for the existence of observers explains that our universe is that way, e.g. because there is an ensemble of universes over which the cosmological constant varies, and the ones where it's too high don't contain any people. So if it's about explanations of the cosmological constant, you do have to talk about observers instead of galaxies; it makes no sense to say that we (a priori) have to observe a small cosmological constant because we have to observe galaxies, unless it's because galaxies are necessary to have observers. The existence of galaxies doesn't explain why we observe a small cosmological constant, just because we live in a universe with galaxies; saying this would be like saying that the existence of cows explains why there is gravity, because we observe cows, and for there to be cows, there has to be gravity.

It's very easy to get confused about these things, and I think it's happened to many people.

Also, in the debate at Edge, I see Susskind saying this:

In particular Weinberg's prediction that if the anthropic principle is true, then the cosmological constant should not be exactly zero, is very similar to the example I just invented.

So, as I understand it (though I haven't looked at what exactly Weinberg did), Weinberg didn't just predict the cosmological constant to be within certain bounds; he predicted it to be nonzero, and not extremely close to zero.