I have a theory about science journalism.
Well, perhaps “model” or “hypothesis” would be a better word. Also, the basic idea isn’t original with me, but I think I can pull together pertinent evidence from a wider variety …

Not too long ago, the way the outside world tells time, Matthew Nisbet and Chris Mooney published a paper in Science on the topic of “Framing.” Well, ’tweren’t really a paper — truth be told, it was more like an Op-Ed wi…

Concerning the superior computational power of evoluion/emergent of physics rule, There are three levels. One extreme level is that like Penrose’s claim about the human mind also evolution and the emergence of the law of physics exhibit superior computational power. An intermidiate step would be that since we do not have understanding of the mechanisms, solving the tentative models we create is computationally unfeasible. An even more mundane statement (which seems rather obvious) is that the randomness involved and unknown “input” prevents us from giving a precise simulation. I do no know where Lee’s opinion lies on this spectrum.

And as for the “no free lunch” theorem that Lee mentioned and its relevance to optimization and to evolution, I found this paper by Olle Haggstrom.

String Theory Landscape

Quantum Effect, however allow a manifold to change state abruptly at some point-to tunnel through the intervening ridge to a nearby lower valley.

See here

AS a layman I needed to understand the differences of String theory Landscape and Fitness landscape? Are others having the same problem?

Fitness landscape

In evolutionary biology, fitness landscapes or adaptive landscapes are used to visualize the relationship between genotypes (or phenotypes) and reproductive success. It is assumed that every genotype has a well defined replication rate (often referred to as fitness). This fitness is the “height” of the landscape.

See here

Always still a puzzle to me. Thanks for your patience.

I brought evolution back in to clarify(?) Lee’s position. It also has some relevance to at least Steve Weinberg’s ‘justification’ for the Anthropic Landscape, e.g., see:

http://www.pipeline.com/~lenornst/Anthropic.html

The Landscape - For Real This Time

Clifford:

Lets’s think of height as representing potential energy, just like on our earlier sketch. Let’s think of the valley (the surface of the lake, say) as being at zero energy. Then all higher elevations are positive energy, and you see that there are several interesting features. …

See here for link to article.

Look familiar? How many time since then have we seen “the familiar” dressed up in what another may say of the landscape?

Somehow, the 2 links I provided, were deleted. They are:

http://www.pipeline.com/~lenornst/Life.html and

http://www.pipeline.com/~lenornst/SETI.html

You note,”The issue…seem(s) to apply even for one or a few different species co-evolving together”. It applies for many different species evolving together, in the sense that the problem gets to be even more complex.

If you need infinite time to solve a problem, then in the real world the best you can get is a good approximation. And if you can’t expect even a good approximation in a few billion years, the problem is hard enough to fit under “no free lunch”; although that also is only an approximation.

Maybe this provides some clarification?

I see, thanks. (But for reading your papers please give a precise reference/link.)

The issue you refer to (if I understand you correctly) seem to apply even for one or a few different species co-evolving together. (Not just for the “real thing”.) I realize that you cannot write a computer program repeating precisely or even approximately an evolutionary process that depends on unknown parameters and may have chaotic components. I thought Lee meant something stronger. (Maybe you mean something stroger as well but in this case I do not understand what it is.)

Specifically, Kauffman’s argument that Lee mentioned based on the “no free lunch theorem” is supposed to say something stronger about impossibility - in principle - to optimize in the context of evolution. Some people I talked to were very skeptical that the no free lunch theorem (whatever it is; I am only vaguely familiar with what it is, but they were,) says much about optimization in general, and were especially skeptical about any relevance to the theory of evolution.

I don’t want to put words in his mouth, but I believe Lee was referring to the improbability of evolution approximately repeating itself, were it even to start with a same progenitor ‘bacterium’.

This is usually referred to in evolutionary biology as the problem of convergence. How likely is it that any ’similar’ structural or functional, features produced in one evolutionary lineage, will be able to arise, completely independently, (using different DNA sequences, let alone the SAME sequences)? This obviously depends at least upon the complexity of the feature, the time available, and the properties of the environment (both physical and biological).

There is a great deal of evidence for convergence in the evolution of features and functions like flight and swimming adaptations. The case for higher levels of complexity…like the evolution of a nerve, of light sensing organelles, and of eyes is less clear cut (see my Science and Physics Today discussions of these matters: and ).

10^500 may seem big, but the combinatorics of possible DNA messages dwarfs, that magnitude into complete insignificance. Given infinite time, biological evolutionary processes MIGHT be approximately ergodic, but not likely over as little as a few hundred billion years. In this sense (rather than “in principle”), “The evolution process can not be simulated…by a computer”.

Hope this helps.

Thank you very much for your answer.

I asked “Are you saying that what nature produced is so fit to the extent that the evolution process cannot be simulated, even in principle, by a computer?”

To which you answered:

“But when we come to the real thing, with millions of different species co-evolving all at the same time, one faces a problem of enormouosly greater complexity than evolution of a single species on a fixed fitness landscape. There are claims that it may be impossible to create a static landscape to represent something like the space of all possible combinations of all possible viable biological species on a planet. There are also results like the “no free lunch theorem” which states that no single optimization procedure works better than random search on all possible landscapes, that imply that unless you know a lot already about the landscape you cannot design a good optimization procedure for it. This means that no single computer program can both anticipate all possible landscapes that might be produced by coevolution of a large number of species and simulate evolution on it efficiently. …”

Your suggestion, Lee, that the fitness achieved in our world is not something that can be simulated (even in principle) by a computer is quite far-reaching!

(Of course, we are not talking about a simulation that will lead to precisely the same outcomes, since those depended on a lot of randomness and relied on unknown parameters. But we are talking about comparably successful processes.) This opinion resembles in some general terms Penrose’s claims about the human brain.

While being naivly somewhat appealing, as far as I know ideas about proceesses in nature which are capable to achieve optimization beyond the capacity of computers seems contrary to emerging insights about computation. It is not clear to me if by “computational complexity” you refer to the same thing as the people in computer science. (I think the paper of Douglas and Denef that you mention and regard as “no news to anyone who was familiar with the literature on evolution on landscapes in theoretical biology” is really talking about technical terms from the theory of computer science.) But if you do talk about the computer science notion of “nor feasible” , I do not see what can be a possible interpretation of your ideas on this matter. What can be a mechanism to achieve fitness that produced something computers cannot match?

Claims of similar nature and the reference to the “no free lunch” are prominent in the intelegent design literature. Of course, advocates of intellegence design may have or may quote serious scientific ideas. But in this particular case, I do not see any reasonable scientific interpretation of claims which attribute to any optimizatin process in nature, such as evolution, computational powers which are superior than the powers of computers. (I also very vaguely remember that the “no free lunch” argument is considered rather weak.)

E8 is a lesson on diversity of symmetry, and “the 11th” the movement to branes?

iMagine what goes on in this abstract thinking? Even to me it is bewildering. Yet the brane diagrams help. How did we get there? The “complexity” quantumly involved, would have to be mind boggling?

I have a great deal of respect for ST, it is actually kinda fun and some of its results suggest it is probably in the right track. Now, from there to even imagine is the ONLY way there is a huge gap. It seems like an intelligent design type of thing: Let ST be…

By the way,

“… and that the interactions of these states is always consistent with a string interpretation.”

Even so, that doesnt mean at all it is the ONLY consistent theory of QG in any sense, and one more time (sorry to bother repeating myself), it is always based on the assumptions.

G

ps. I wonder actually, how is it possible to have a theorem which will *prove* from scratch that the *only* consistent world is 11 dimensional…

Just drawing attention to the dates of publication and comparison of views. I was thinking of “Benchmarks” in terms of the progressions, that could have been marked as successes, and help one to realize that there was still a process unfolding?

I thought these two views countering one another?

A second obstacle arises from the theory’s reliance on the idea of spontaneous symmetry breaking to explain why each of the elementary particles we see in the world has different properties. While this is a beautiful idea, there is a certain ad hoc quality to how it is realized. To this date, no one has so far observed a Higg’s particle and we have only a very imprecise idea of their properties. Page 61, The Life of the Cosmos by Lee Smolin ISBN 0-19-510837-x 1997

As a Lay person I was thinking of the word “ad hoc” in Lee’s statement, and wonder if this is still reflected in his views of today. This was a build up and precursor to the statement about string theory in question according to Lee’s book statement??

Unravelling String Theory,by Edward Witten 29 Dec 2005

String theory is the only known generalization of relativistic quantum field theory that makes sense. The framework of special relativity plus quantum mechanics is so rigid that it practically forces quantum field theory upon us. The tightness of the modern framework is one of the main reasons why physicists were able to discover what has become the standard model of elementary particles.

Have we moved past this today and “all” in agreement?

A related issue is “exaptation”-the fact that the selective advantage confered by a trait can change unpredictably through evolution by the discovery of a new strategy or niche,never before used or occupied. There are claims in the literature that there is no fixed procedure that can anticipate such novel shifts in fitness. This implies that the contribution to fitness of a given attribute of a species can change unpredictably as a result of changes in the environment brough on by the co-evolution of many other species. This means that there is a limit to the validity of studying evolution on fixed fitness landcapes.

Imagine that you list all the traits that contribute to the fitness of bacteria. Could you then infer from these the traits that confer fitness on multicell creatures? On the fitness landscape of bacteria there is no meaning to “flying” or “having a song which communicates health and vitality”. Yet all life evolved from bacteria. The claim that you could simulate all evolution on a computer requires anticipating in advance all possible traits that contribute to fitness in all possible biospheres and knowing how these are coded into instructions to make proteins.

One source for these issues are the last two books of Stuart Kauffman.

Thanks,

Lee

Mark clarifies what he means in this comment. If you wish to contribute something sensible to the discussion, please reply to him on that thread, to avoid confusion.

(Update: I see Mark replied here too. Well, ok, carry on. But do read his comment on the other thread.)

cheers,

-cvj

No one ever claimed to have such a theorem. In 1895, Lord Kelvin declared that “heavier-than-air machines will never fly.” No proof was offered. And he was immediately challenged with the counterexample of birds. To which his only answer was that birds were different because they were alive.

Lee: is your position that case (1) on your list, “Ours is one of a vast collection of universes with random laws”, could not possibly be true? That was the conclusion I drew from what you wrote in your book, and I am left unclear by what you wrote above.

What if, someday, someone proves a theorem that shows that string theory provides the only mathematically consistent framework for quantum gravity?

And what if someday somebody proves a theorem that bodies heavier than air cannot fly?

You will have to define first what you mean by “quantum-gravity”, and certainly you would get the desire theorem if the hypothesis is: “string theory is the only TRUE consistent framework for quantum gravity”, although the whole thing would become a logic puzzle.

Nature in the other hand is a different story. I regard mathematics (and ultimately logic) as a fantastic tool to help us trying to understand the universe, and possibly the best we can get. However, mathematics itself isnt physics, and [most] mathematicians dont cranck their heads trying to come out with simple leading ideas or models to explain data and make predicitons. One of these new ideas may lead to an experiment which will show us that QM isnt the final word and will make us rethink what a quantum theory of gravity could be.
I like what mathematicians say about their theorems, they are as useful/strong as its assumptions. And these are ultimately what makes the difference.
I’ll give u a simple example. Let’s say we find Lorentz Invariance is broken, or evolution violates unitarity. Then we would have to go back and change our assumptions and start all over, falsifying ST along the way perhaps?

I like philosophy (perhaps too much) as well, and truly believe it can give us hints and lead our path towards understanding nature, but we all want to do ‘Science’ at the end of the day, dont we?

G

Dear Lee, It is not clear what precisely you are referring here to. Are you saying that what nature produced is so fit to the extent that the evolution process cannot be simulated, even in principle, by a computer?

Of course I am not claiming to have been part of the discovery that string theory has a vast number of compactifications, or ground states. Nor was I the first to think about a multiverse cosmology, Linde’s eternal inflation was prior to my thinking about this. Nor was I the first to think about natural selection as a model for how to explain how the laws of nature of our universe were chosen, the philosopher Charles Sanders Pierce suggested this in 1893, although I did not know of this when I wrote the first papers on cosmological natural selection. I do claim that I was one of the first, if not the first, to propose that there would not be a dynamical vacuum selection principle in string theory leading to a unique vacuum state and instead to take seriously that the output of the theory would be a vast landscape of theories. I believe I was the first to define the problem of how to make falsifiable predictions from the landscape of string theories, and I believe that so far I have given the only solution to it.

Of course part of the reason for my insisting on this is personal: it would be nice to get credit for the notion that the connection between string theory and experiment must go through the landscape, especially given that so many people insisted I was wrong about this then, and especially since the term I introduced for this is the one that is now in common use.

But part of my reason is for the science, it is incredibly frustrating to have thought through the possibility that the AP be combined with the string landscape in the early 90s and to have understood why it, and more generally static, random distributions, on the landscape can’t work, to explain this in a book, and then to watch very smart people waste years playing with the ideas that one has already considered and understood cannot work. For example, it was nice to see the discussions of the difficulties of minimizing potentials on the landscape due to issues of computational complexity of Denef and Douglas, but this was no news to anyone who was familiar with the literature on evolution on landscapes in theoretical biology. The problem of evolutionary biology begins with the question of how nonetheless, in spite of the computational complexity of the fitness landscape in biology, nature produces organisms which are so fit.

Dear Mark,

Even if there were a unique theory of quantum gravity one would still need experiment to show that this was relevant for nature. This is because there is an alternative proposal, which is that gravity is not quantum mechanical but that instead quantum theory is modified or itself is only a low energy limit of a very different cosmological theory, applicable only for small subsystems of the universe.

But having said this, given that in LQG there is both a rigorous existence and uniqueness theorem for the quantization of diffeomorphism invariant gauge theories (the LOST theorem) and given that there are now calculations of the graviton propagator, there is a lot more evidence than there was five years ago that LQG does provide a consistent, finite quantum theory of gravity with a good low energy limit. There is also evidence accumulating that CDT has a good low energy limit in which spacetime emerges in 3+1 dimensions. Thus, while there is more to do on both approaches, it is looking less and less likely that string theory is either the unique or the best approach to quantum gravity,

Thanks,

Lee

Elliot

(rediscovery in the sense that Einstien had originally proposed a non-zero CC then backed away from the claim.)

You seem to be under the impression (I’ve pointed out this flawed assumption before) that the “bulk of the community” has made up their minds in favour of the AP. It is not true that the bul has made uptheir minds one way or anohter. It is also not true that the bulk of the community is even *working* on the AP.

I also have to say that I find this claim of yours to have invented, or introduced, or discovered the landscape in string theory to be far from convincing. I don’t see (in broad brushstrokes at least) how the idea of a landscape of solutions was not evident right after the first (for example) Calabi-Yau compactification, combined with the knowledge that there is a vast number of CY manifolds. Phase I of the modern discussion of a landscape of solutions of string theory, and the phenomenological issues it raised, began around then… in the 1980s. I don’t recall you being on any of those papers. Most people did, I’ll agree, prefer to learn more about the theory first before concluding from perturbation theory alone that that was all there was. But there were several serious discussions of the other possibility, I believe, although I do not know if much of it made it to print. Phase II (where some researchers are now) came about with constructing landscapes of long-lived vacua with finite cosmological constant, with the aid of some improved knowledge of control of some non-perturbative issues (but far from anything like a satisfactory non-perturbative understanding of the theory).

So I would say that your discussions several years later are notable, and probably interesting, but it is really quite a distortion (by almost any definition) to say that you discovered/invented the landscape in string theory and was just “waiting for the string community to catch up”. I will grant you that you might have been one of the first to try to see what would happen if the landscape of solutions was all there was, and what that would mean. But that is a bit different from what you are claiming.

Cheers,

-cvj