I How do string theorists reply to Roger Penrose

[ohwilleke]

I would be curious to know the extent to which there are particular innovations of string theory, if any, that are "severable" from the overall structure of M-theory.

If there are, that might justify the discipline. If all the work is irrevocably tied to the whole, the really undermines its usefulness as an intellectual endeavor.

 

[Urs Schreiber]

I would be curious to know the extent to which there are particular innovations of string theory, if any, that are "severable" from the overall structure of M-theory.

All of them are. It goes the other way around: there is a system of phenomena in string theory as such, and the observation that as a whole they seem to point to an overall structure to which they might all be connected.

 

[MathematicalPhysicist]

Did he say that before or after receiving the Nobel Prize?

I don't think anyone would quote someone who isn't famous, and Einstein wasn't famous before he won the prize, was he?

 

[Demystifier]

I don't think anyone would quote someone who isn't famous, and Einstein wasn't famous before he won the prize, was he?

First, Einstein became famous before he won the prize. Second, once he became famous, others may wanted to quote his statements that he wrote even before that.

 

[MathematicalPhysicist]

First, Einstein became famous much before he won the prize. Second, once he became famous, others may wanted to quote his statements that he wrote even before that.

When did he start being famous to the wide audience?

 

[JorisL]

When did he start being famous to the wide audience?

This is a guess but probably earlier than one would expect.
The German state promoted science between the two world wars if I'm not mistaken.
In fact during the Weimar republic phase science was considered as a part of culture. People would listen to scientific lectures like we watch plays today.
It was the epitome of culture (not even sure if this is an exaggeration, it's been a while I read/learned about this stuff).

 

[Demystifier]

When did he start being famous to the wide audience?

After an observation of light deflection by Sun, predicted by his general theory of relativity. The observation was done by Eddington in 1919.

 

[Paul Colby]

So instead of spending time on the popular prose of those authors you refer to, why not drop all that, pick up Polchinski's textbook, open it on page 1, and start reading.Take a pen and paper with it, and try to follow the arguments. Such as to finally know what we are actually talking about.

This is a very good point to which I would ask, what known results of the theory justifies such an expenditure of effort? If understanding only leads to more technical questions there is no way to recoup time wasted. To the unwashed like myself there appears to be no usable phenomenology in these theories.

 

[Haelfix]

I don't know what you mean by 'usable phenomenology'. If you mean, the sort of things that high energy physicists study, then perhaps it might be wise to browse new papers in Hep-pheno, and note that there is something like a paper a day that deals with some aspect of stringy phenomenology (which is a vast subject with tens of thousands of papers).

 

[ShayanJ]

This is a very good point to which I would ask, what known results of the theory justifies such an expenditure of effort? If understanding only leads to more technical questions there is no way to recoup time wasted. To the unwashed like myself there appears to be no usable phenomenology in these theories.

This post is based on some naive assumptions about how people learn physics and eventually choose what to work on!

 

[Paul Colby]

I don't know what you mean by 'usable phenomenology'.

Fair enough. One should be able in some way to convert theory into observational predictions that can be compared with experimental results in a unique way (I know I'm old fashion this way). In the standard model there is a well defined way of doing this (eh more or less). If it's possible to start from a pure string theory on however many dimensions and produce numerically accurate branching ratios for all those measured with LHC or some other experiment, then my understanding of the state string theory is truly remiss. If application of a theory isn't unique or requires essentially assuming the answer then it's not really what I would consider a theory. IMO the shear volume of papers on a topic isn't the guaranty of relevance it used to be.

 

[MathematicalPhysicist]

Fair enough. One should be able in some way to convert theory into observational predictions that can be compared with experimental results in a unique way (I know I'm old fashion this way). In the standard model there is a well defined way of doing this (eh more or less). If it's possible to start from a pure string theory on however many dimensions and produce numerically accurate branching ratios for all those measured with LHC or some other experiment, then my understanding of the state string theory is truly remiss. If application of a theory isn't unique or requires essentially assuming the answer then it's not really what I would consider a theory. IMO the shear volume of papers on a topic isn't the guaranty of relevance it used to be.

I heard some considered it a framework and not a theory, whatever the difference between the two may be.

 

[Paul Colby]

I heard some considered it a framework and not a theory, whatever the difference between the two may be.

I'm concerned that a framework involves much more hand waving than a theory. In any case I should be able to fine at least a couple (out of 1000s) of papers that will give me a better perception of the applications. To hear that string theory is routinely used in high energy phenomenology indicates a much more complete "theory" than I was led to believe based on what I've seen of the literature.

 

[MathematicalPhysicist]

I'm concerned that a framework involves much more hand waving than a theory. In any case I should be able to fine at least a couple (out of 1000s) of papers that will give me a better perception of the applications. To hear that string theory is routinely used in high energy phenomenology indicates a much more complete "theory" than I was led to believe based on what I've seen of the literature.

Well mathwise it seems interesting enough to learn, is it a physical theory that one day engineers will use (in the very far future) to harness nature to our will as was done with QM, CM,EM and Statistical Physics (I don't see many applications of GR in engineering)? to tell you the truth I have my doubts, well first we need to incorporate GR into Control Theory in a meaningful way.

But I digress from the topic of this thread, there's a lot to be learned.(the understatement of the century :-D).