The cosmic landscape: string theory and the illusion of intelligent design
Finally, my copy of Leonard Susskind's new book The Cosmic Landscape: String Theory and the Illusion of Intelligent Design has arrived.
I posted some comments earlier (see here) about the weak form (i.e. not driven by an external goal-seeking agency) of the anthropic principle and its relationship to Bayes theorem, and made some generally disparaging remarks about the hostile attitude of some physicists to the weak anthropic principle. There was some misplaced criticism of Bayesian methods posted here, but I don't know whether this was related in any way to my earlier comments on Bayes theorem and the anthropic principle. However, I do know that it prompted me to reinforce my statement about Bayesian methods here, which led to this spectacular response, and my own response to that here. I will not comment further on that exchange; I leave it for you to read for yourselves.
Anyway, now I actually have Susskind's book, I can focus more on the particular details of his arguments, rather than my own favourite argument based on Bayes theorem. What I plan to do is to work through the book in stages, and to report back here at each stage to explain the material that I have read, and to interpret it in my own particular way.
For the record, I have no prior prejudice about whether the cosmic landscape (i.e. the possibility of choosing between multiple alternative laws of physics) exists or not, but I do care about following up all credible avenues of enquiry, until they can be shown to be wrong because they are inconsistent theoretically or experimentally. In a nutshell, that is the scientific method. So we have to view the cosmic landscape as a valid possibility for now.
posted by Stephen Luttrell @ 5:21 pm
15 Comments:
I posted some comments earlier (see here) about the weak form (i.e. not driven by an external goal-seeking agency) of the anthropic principle and its relationship to Bayes theorem, and made some generally disparaging remarks about the hostile attitude of some physicists to the weak anthropic principle.
Lubos hates the anthropic principle more than he hates LGQ theorists, but I honestly don't know where you get the idea that the weak anthropic principle excludes an external goal seeking agency.
You referenced "Wikipedia" unbelievably enough:
http://en.wikipedia.org/wiki/Anthropic_principle
Weak anthropic principle:(WAP): "The observed values of all physical and cosmological quantities are not equally probable but they take on values restricted by the requirement that there exist sites where carbon-based life can evolve and by the requirements that the Universe be old enough for it to have already done so."
There is evidence that a goal seeking agency like our exanding universe would isolate its forces to produce life-conducive "sites" if the universe produces carbon based life-forms as a means to efficiently satisfy the second law of thermodynamics in an expanding universe that has an increasing negative pressure component.
If I thought that WAP had any "intelligent design" in it then I would abandon it immediately.
It seems that you are interpreting the wikipedia definition of WAP back to front. Unfortunately, I now see that the wording of the wikipedia definition of WAP is ambiguous in a way that makes it read as if it is a definition of the strong anthropic principle (i.e. the religious definition, where an external goal-seeking agency is tuning things).
In WAP the physical quantities are not restricted a priori but are restricted a posteriori. It is the knowledge that carbon-based life exists that is used a posteriori to restrict the possible values that the physical quantities might take. And, lo and behold, the values that we observe lie within the (sometimes very narrow) ranges that we have deduced from the observed fact of our own existence.
A practical way of realising this type of scenario without invoking "intelligent design" is to construct a priori an ensemble of universes, all having different laws of nature. This is then converted a posteriori into a much smaller subset of universes by the observed fact that we exist. This is where the "illusion of intelligent design" comes from.
WAP is essentially the Bayesian "inverse probability" argument that I have already described in detail. Causes give rise to effects, and Bayesian inference allows you to invert this to deduce the causes that could give rise to the observed effects.
A practical way of realising this type of scenario without invoking "intelligent design" is to construct a priori an ensemble of universes, all having different laws of nature. This is then converted a posteriori into a much smaller subset of universes by the observed fact that we exist. This is where the "illusion of intelligent design" comes from.
(i.e. the religious definition, where an external goal-seeking agency is tuning things).
Two points:
1) Assuming that intelligent design *could* be inferred by the anthropic principle, then a multiverse won't save you from this until and unless you can prove that the multiverse exists, or if string theory bears out to be the one true theory of everything. That's because the anthropic principle is a fact of the observed universe, so you can't use unproven theoretical speculation against the implication for specialness.
2) Lenny is flat wrong about this. As I demonstrated via my "entropic" interpretation, goal oriented design or structuring in nature cannot be construed as evidence for "intelligent" design without direct proof.
Lenny is playing in a field that he knows very little about.
In your first paragraph you accurately quoted from my previous comment, in which I explain how the weak anthropic principle can be realised.
Then in your second paragraph you erroneously juxtaposed another quote from my previous comment, which relates to the strong anthropic principle, and not to the weak anthropic principle.
The "illusion of intelligent design" is precisely the same as the "weak anthropic principle". The words "illusion of" correspond to the word "weak". If you omit the words "illusion of" then you have to replace the word "weak" by the word "strong".
The difference between the weak and strong versions of the anthropic principle is so fundamental that there is no point in discussing anything until this issue is properly understood by everybody. Maybe I will post a summary of this separately.
For instance, in WAP one does not infer "intelligent design", rather one infers the "illusion of intelligent design". Susskind chooses this phrase very carefully, and he is emphatically not inferring "intelligent design" (i.e. without the "illusion of" qualifier). Thus he is poking the people who propose "intelligent design" squarely in the eye, saying in effect that they are naive to fooled by such an illusion.
Of course, I have not yet finished Susskind's book, so I am making the assumption that he does not invoke the strong anthropic principle later on. However, the Laplace quote "Your Highness, I have no need of this hypothesis" at the front of his book suggests to me that he uses only the weak anthropic principle.
The difference between the weak and strong versions of the anthropic principle is so fundamental that there is no point in discussing anything until this issue is properly understood by everybody. Maybe I will post a summary of this separately.
Yeah, maybe you should, because I'm not EVEN convinced that you're not making up your own ideas based on your infatuation with the Bayes theorem:
The "illusion of intelligent design" is precisely the same as the "weak anthropic principle".
I don't think so... and neither does Lenny:
http://www.newscientist.com/channel/opinion/mg18825305.800.html
Susskind very clearly expressed rationale for these observations in his interview with New Scientist concerning his new book, The Cosmic Landscape: String theory and the illusion of intelligent design.
Amanda Gefter:
If we do not accept the landscape idea are we stuck with intelligent design?
Leonard Susskind:
I doubt that physicists will see it that way. If, for some unforeseen reason, the landscape turns out to be inconsistent - maybe for mathematical reasons, or because it disagrees with observation - I am pretty sure that physicists will go on searching for natural explanations of the world. But I have to say that if that happens, as things stand now we will be in a very awkward position. Without any explanation of nature's fine-tunings we will be hard pressed to answer the ID critics.
Lenny is saying that the "illusion" might be real if there is no multiverse, so it's only an "illusion" if the landscape is for real.
Lenny is saying that the "illusion" might be real if there is no multiverse, so it's only an "illusion" if the landscape is for real.
Lenny is wrong... is my point... for the reasons that I gave, which are exactly valid in context with Lenny's statement.
You say:
Yeah, maybe you should, because I'm not EVEN convinced that you're not making up your own ideas based on your infatuation with the Bayes theorem:
The weak and strong forms of the anthropic principle are well-defined, and Bayesian methods are also well-defined. I have posted a lot of material on this recently, so I will not repeat it here.
The following book gives a very detailed treatment of all of this: John Barrow and Frank Tipler, "The Anthropic Cosmological Principle", OUP, 1986. You will find the relationship between Bayes theorem and WAP discussed in the introduction to this book. Yes, it is that fundamental.
You say:
Lenny is saying that the "illusion" might be real if there is no multiverse, so it's only an "illusion" if the landscape is for real.
Absolutely! That is the whole point. If there is no multiverse then that approach to WAP has nothing to work with, so it is falsified. That is the scientific method.
If there is no landscape then Susskind says:
I am pretty sure that physicists will go on searching for natural explanations of the world. But I have to say that if that happens, as things stand now we will be in a very awkward position.
Surely, this statement is correct? Currently, there is no derivation of the fine tunings, and it is an "act of faith" to assume that such a derivation will be possible in the future. So if there is no landscape it would make it difficult right now to give a convincing counterargument to proponents of "intelligent design".
Like I said before, I am neither for nor against the landscape. For me, it is merely one of the possibilities that is currently on the table.
I may be wrong, but it seems to me that you have an a priori dislike for the landscape. Am I right? If I am, then I have to ask you why you feel this way.
Surely, this statement is correct? Currently, there is no derivation of the fine tunings, and it is an "act of faith" to assume that such a derivation will be possible in the future. So if there is no landscape it would make it difficult right now to give a convincing counterargument to proponents of "intelligent design".
Of course that statement is correct, but not for the right reasons. His statement is correct because Lenny knows that scientists won't buy into the creationists hype, even though he **erroneously believes*** that the failure of the landscape means that they have a valid basis for argument.
He is dead-wrong about this, as are you, apparently, is my point, and it is critical to the debate IF he's wrong.
it is an "act of faith" to assume that such a derivation will be possible in the future.
No, it is not, because we know that the cause for every known effect is natural in origin, so god theories are necessarily ruled-out without direct proof. Natural ID theories are too star-trek-like implausible without direct proof that ET didit, to have considerable merrit.
UNLESS you give them pseudo-ammunition that equally motivated antifanatics will counter with their own lame rationale that is predisposed to downplaying the significance of the implied "specialness".
Which brings us to this...
I may be wrong, but it seems to me that you have an a priori dislike for the landscape. Am I right? If I am, then I have to ask you why you feel this way.
Which leads back to this:
Currently, there is no derivation of the fine tunings, and it is an "act of faith" to assume that such a derivation will be possible in the future.
I personally don't see it as an "act of faith", because I believe that I have solid evidence that a near-flat anthropic universe is the most natural and only configuration that an expanding universe can have.
So I don't so much have anything against the landscape as I don't see it as necessary.
Assuming I'm right, we don't need people like Lenny screwing-up any hope that science might ever recognize the possibility that maybe we're here for good physical reason to the thermodynamic process of the universe because everybody's too busy trying to come up with new rationale that enables them to HIDE FROM the special implications, instead of facing them for their full implication.
I know from experience that this rationale is what Lenny is talking about when he says that "scientists will keep looking for natural answers"... but that's the wrong way to do science, because it's pre-prejudiced to look for more ways to downplay the implied significace, rather than to deal with the full possibility.
Assuming that I'm right, then a full derivation of the fine tunings will never be possible as long as science willfully ignores the special implications by automatically looking in the opposite direction for a more-random answer.
You have to know that this is a correct statement in this context.
You said:
Lenny knows that scientists won't buy into the creationists hype, even though he **erroneously believes*** that the failure of the landscape means that they have a valid basis for argument.
I don't think he is saying it as strongly as that. He recognises that if the landscape is actually true, then it is a powerful counterargument to "intelligent design", and if it is false then we have lost a powerful counterargument.
I don't know whether the landscape is true or false, but I am interested in evaluating the consequences of it being true.
When I said "it is an "act of faith" to assume that such a derivation [of fine tunings] will be possible in the future" you said:
No, it is not, because we know that the cause for every known effect is natural in origin
We don't actually know that; it is an assumption that natural explanations are to be preferred. However, this assumption has a good track record, so I am prepared to go along with it. But we also have to be prepared to accept the predictions of our theories even if they do not fit in with our prior prejudices. In this respect, maybe the landscape will turn out to be true.
You said:
So I don't so much have anything against the landscape as I don't see it as necessary.
Nor do I see it as necessary! I see it merely as a possibility that has not yet been ruled out, and which has this very interesting consequence in terms of the weak anthropic principle.
You said:
Assuming I'm right, we don't need people like Lenny screwing-up any hope that science might ever recognize the possibility that maybe we're here for good physical reason to the thermodynamic process of the universe because everybody's too busy trying to come up with new rationale that enables them to HIDE FROM the special implications, instead of facing them for their full implication.
I think you are saying that we should strive to derive everything from first principles (e.g. string theory ==> unique laws of physics), and should resist the temptation to "cop out" with the first convenient solution (e.g. string theory ==> landscape ==> WAP). If so, I agree with you. But all we have thus far is a landscape of solutions, so we should at least spend some of the time following up the consequences of that. Who knows? It might even turn out to be the way nature works!
You said:
Assuming that I'm right, then a full derivation of the fine tunings will never be possible as long as science willfully ignores the special implications by automatically looking in the opposite direction for a more-random answer.
That is true. We certainly should not give up trying to derive everything from first principles. I don't think Susskind is advocating that, but rather he is pointing out the interesting (from the WAP point of view) consequences of the current state of the art (i.e the landscape).
Postscript: All of this exchange has resulted from the mere fact that I announced that I would read The cosmic landscape: string theory and the illusion of intelligent design and report back to this blog what I found in the book. I never expected to have such a detailed discussion this early on, but I have tried as far as possible to be non-committal in my responses.
You said:
Lenny knows that scientists won't buy into the creationists hype, even though he **erroneously believes*** that the failure of the landscape means that they have a valid basis for argument.
Steve Replied:
I don't think he is saying it as strongly as that. He recognises that if the landscape is actually true, then it is a powerful counterargument to "intelligent design", and if it is false then we have lost a powerful counterargument.
There is no argument FOR intelligent design if the landscape is not valid, for reasons repeated now.
This extremely important point seems to have no affect on you, but you insist that Lenny said less than my direct quote of him indicates:
Steve's suspiciously kind translation:
if [the landscape] is false, then we have lost a powerful counterargument.
Counter-argument to what?
What Lenny actually said:
Without any explanation of nature's fine-tunings we will be hard pressed to answer the ID critics.
Hard pressed to answer what... ?
I see a clear indication that your responses aren't the least bit "non-committal", as you claim, but regardless... I got into this because I didn't understand your interpretation of something that I see more as a special and general case.
The WAP is about the environmental enablement.
The SAP is about why...
The reason that this isn't obvious is because the current tautologous form of the anthropic principle is incomplete.
Sorry if I missed something, but I don't see any reference to Lee Smolin's notion of Comological Natural Selection as a nonteleological alternative to Intelligent Design when accounting for anthropic coincidences. Basically, he taps Darwinian logic to come up with a model of the evolution of universes in which physical constants that skew universes toward black hole production give those universes an adaptive advantage in the ensemble of universes. More at http://www.starlarvae.org/Star_Larvae_Cosmological_Natural_Selection.html
Counter-argument to what?
and
Hard pressed to answer what... ?
I agree with your implied comment, that the "intelligent design" adherents have no scientific basis to their arguments. However, these people exist in large numbers and they are not going away, and from their point of view their arguments are perfectly valid. We have to somehow convince them of the validity of our arguments, even though we know that (viewed from our point of view) they don't have a scientific argument.
If the landscape is real then its consequences for fine tuning would be relatively easy to explain. The only place "intelligent design" could then hide is in the specification of the underlying laws from which the (assumed) landscape derives. Note that in my customary non-committal style I am not asserting that ID does hide there.
On the other hand, if the landscape is false then we have to use some other argument for fine tuning, and we have not got such an argument currently.
In a nutshell, that is how I interpret Susskind's remark:
Without any explanation of nature's fine-tunings we will be hard pressed to answer the ID critics.
I agree with your implied comment, that the "intelligent design" adherents have no scientific basis to their arguments.
However, these people exist in large numbers and they are not going away, and from their point of view their arguments are perfectly valid.
So, what?... they've already proven that religously motivated pseudo-theories can't win in court.
We have to somehow convince them of the validity of our arguments, even though we know that (viewed from our point of view) they don't have a scientific argument.
No, that's false.
If the landscape is real then its consequences for fine tuning would be relatively easy to explain. The only place "intelligent design" could then hide is in the specification of the underlying laws from which the (assumed) landscape derives. Note that in my customary non-committal style I am not asserting that ID does hide there.
Yes, you are saying that there is an implication for something that scientists don't like, (fear?)... if we can't *explain it away*. Once again I will also point out that "exlaining it"... means rationalizing away evidence for purposeful structuring in nature, rather than to recognize that it exists... which isn't science anymore than ID is.
On the other hand, if the landscape is false then we have to use some other argument for fine tuning, and we have not got such an argument currently.
No, that's false... as I've already stated, (and demonstrated), we know of no cause that isn't natural in origin, so there is no priori reason to conclude that the hardest proof for purposeful structuring in nature isn't of natural origin, as well. Like I told Lawrence Krauss...
http://cosmicvariance.com/2005/11/07/krauss-on-intelligent-design-religion-and-string-theory/
Origins science isn’t about speculative and known-to-be-fundamentally-flawed theoretical physics projections, multiverse theories have no business in origins science, unless you are “fending-off” an equally unsubstantiable attack. This is fine if the attack includes something the ludicrous plausibility of alien intervention, but it is NOT okay when the anthropic principle is used to support the idea that a fundamental and goal-oriented form of structuring/”design” forever exists in the energy of nature.
If this is correct for only one possible universe, say, the one that’s actually observed and “known”, then this is what defines the values of the forces and the asymmetrical reason why the forces cannot be unified at any level.
If you want to beat-back the lame hop to supernatural forces that’s supposed to lie beyond evidence for goal-oriented “design in nature”, then do it simply, by the fact that there is absolutely no evidence that the structuring of our universe isn’t forever inherent, regardless of how it started for us, and regardless of whatever mathematical “idealizations” may be pointed “toward” by our theories. That doesn’t even come close to actually getting there.
You can’t conclude anything else without an unprovable assumption, so don’t even open the door beyond empiricism until these guys finally find a good reason to quit fighting with each other over which theory is the most screwed up!
"In a nutshell, that is how I interpret Susskind's remark:"
Without any explanation of nature's fine-tunings we will be hard pressed to answer the ID critics.
You conveniently forgot that this was in response to Amanda Gefter's question of whether the illusion means that are left with a ID theory if the landscape fails.
Lenny:
we will be hard pressed to answer the ID critics.
Lenny gave the IDists ammuntion for no reason whatsoever, because the landscape **does fail** to be a valid argument against the special implications that are inherent to the "illusion" until or unless the landscape is is proven, or until it proves to be necessary to the one true theory of everything.
http://physicsweb.org/articles/review/18/12/3/1
Susskind expresses the hope that the sentence...
"the appearance of intelligent design is undeniable"
...will not appear out of context on a religious Internet site.
Fat chance!
It is a fact... Lenny gave the IDists unnecessary ammunition.
I now realise that opinions on these issues are even more polarised than I had anticipated when I originally decided to "review" Susskind's book.
You will be pleased to learn that the effect of your comments is to encourage me to do an even more complete job of explaining Susskind's book than I had originally planned. I look forward to reasoned and focussed discussion on what I post.
I can appreciate what you're trying to do, but I personally would like to see the point seriously addressed that the subject is NOT "polarized" to either/or.
It is not polarized to either, we have to "explain-away" evidence for purposeful structuring in nature, or we have a problem with IDists.
This mentality is killing science.
www.anthropic-principle.ORG
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