Monday, September 03, 2007

Do not miss this!

Do not miss this! The Stringscape: The Latest Master Pieces From Liers's Club in the newest Physics World. The following pieces give some flavour of what is waiting to become read by you!

However, the richness of string theory that has become apparent in the last decade, and its increasing contact with the real world, gives theorists something to shout about. This is why our main feature on the subject, which started with fairly modest intentions, has ballooned into the longest ever to appear in Physics World. As the views of even many non-string theorists in the article make clear, the theory still holds all the potential it ever did to revolutionize our understanding of the universe.

...few string theorists think that the sometimes negative portrayal of string theory in the popular arena recently has had much of an effect other than to irritate people.

... with the study of 6D “Calabi–Yau” spaces making Witten in 1990 the first physicist to be awarded the prestigious Fields Medal

String theory is full of qualitative predictions, such as the production of black holes at the LHC or cosmic strings in the sky, and this level of prediction is perfectly acceptable in almost every other field of science,” he says. “It’s only in particle physics that a theory can be thrown out if the 10th decimal place of a prediction doesn’t agree with experiment.

This supposed problem with a theory having many solutions has never been a problem before in science.

In terms of changing the way we think about the world, the anthropic landscape is certainly as big as the other revolutions

And much much more!! Just click this and enjoy!!


CarlBrannen said...

It was string theory that got me back to studying quantum mechanics after a hiatus of 25 years, but it was a lack of satisfaction with the foundations of the theory after I bought a text book on it.

Thanks for the link, it is a great article.

Matti Pitkänen said...

For me the starting point was a generalization of hadronic string model: this was 1978, 6 years before super-string models.

What I have been wondering since 1984 is why string hegenomy is unable to admit the failure of the original approach and ask what are the good/bad aspects of approach. Conformal invariance will certainly be an essential element of any future theory and the question is how to generalize it. There is a lot of nice mathematics involved. Spontaneous compactification is however complete nonsense physical and has led to the recent catastrophical situation.

The physical picture of M-theories (if it is possible to talk about it) suggests that the only reasonable manner to formulate M-theory mathematically is by using a supersymmetric generalization of Wheeler's super-space by allowing all possible 10-D metrics and topologies plus mass densities which are singular and concentrated on branes of various dimensions plus path integral over 11-D surfaces.

This would mean giving up the original idea and return to path integral quantization of general relativity but replacing D=4 with D=11. Not very appealing idea. Singular mass densities concentrated on branes are not very attractive idea either.
Even worse, Wheeler's super-space formalism did not work since the infinite-D geometries exists only under extremely strong additional conditions and this is the case also now.

It however seems that admitting the failure of the spontaneous compactification is too humiliating so that the farce is continuing. This despite the fact that there exists highly developed theory based on the notion of fixed imbedding space predicting correctly standard model symmetries, mass spectrum of elementary particles, plus a lot of new physics.

I thought that progress is possible when everyone knows that everyone knows;-). Perhaps I was too optimistic;-)!

Anonymous said...

Some personal reflections...

Sheldon Glashow said: “I have been brought up to believe that systems of belief that cannot be falsified are not in the realm of science.”

IMO this raises the point howto consider some theoretical aspects of physics - as a theory, or as a scientific framework for any theories - and how to do falsify a theory of a theory?

I personally think the notion of the falsification criterion reflects that we are considering sequences of "static theories" that are then proved right or wrong, and replaced when wrong. I find that level of reasoning unsatisfactory.

In an evolutionary perspective it seems to be beeing right or wrong isn't the big questions. Beeing wrong isn't bad, but failing to learn and adapt is fatal.

If we consider theories of theories, or basically a learning and adaption strategy, the falsification criteria seems odd. Because the ultimate criteria is wether the strategy survives or dies.

To me the natural focus should be on the evolutionary/revisionary steps, and the steps of revision upon facing a failure. And I think for intellectual consistency at least, I'd expect to treat our theories, our methods and our references on to the exten possible, equal footing.

Most of the debate I see rarely touch this, does it? Why? The basic issues are fairly clear and profound, but the lack of immediate ideas on howto make progress seems to make many reject this as philosophy or simply irrelevant.

I've got a feeling also that some of the apparent issues in string theory forces them to eventually consider this aspects, which I would assume will lead back to the foundations of what this "string" in some space, is supposed to mean in the first place. Or maybe it really isn't supposed to mean anything in the first place? It's just another "theory". Then, it seems to fair to question the underlying gaming strategy, and wonder when the time is mature to question the old one, and improve it.

Even for the endeavour of theoretical physics and science, I think it's relevant to question the driving forces at play. Curiousity, whatever that means? Economics? or probably all of them at once.

I think this might be an interesting project for applying game theory reasoning to the dynamics of the scientific community and how it interacts with the rest of society for acceptance and funding.


Matti Pitkänen said...

We have roughly similar overall views about what theory is.
I see universe as a structure building gradually about itself and at the same time re-creating itself again and again so that no final theory is possible.

On the long run I am therefore rather optimistic: the recent situation is only a temporary crisis and will be resolved in the natural manner;-).

The tragic of string theory was the overcompetitive atmosphere in theoretical physics which led to this spontaneous compactification catastrophe and induced cannot- lose-the-face syndrome. In a less competitive academic enviroment it would have taken only a few years to abstract out the notions of sub-manifold gravity and to discover the extended conformal invariance of light-like 3-surfaces.

Anonymous said...

> On the long run I am therefore rather optimistic: the recent situation is only a temporary crisis and will be resolved in the natural manner;-).

Yes I'm sure :)

There isn't much learning points in feeding any flamewars. The only rational motive I can see is that the society as a whole may certainly question what they are getting back from the investments made in the particular fields of research which is in part, ultimately my tax money.

No doubt research is definition a search an in some sense by definition a bit speculative, the distinction must be the supporting arugments that justifies the strategy chosen by considering apparent gain,loss and risk. To not play at all means, no learning and no adaption and survival is at stake.