How hard is string theory exactly?

[negru]

in my opinion String Theory is really a hard subject (either considering it physically sensible or just a mathematical curiosity) because the amount of material one must know to learn and pursue the subject.

But this can be an issue with pretty much every single topic in physics. For example just in Classical Mechanics, with dynamical systems and whatnot, there's enough theory to keep anyone occupied for many many years. If you put together all the random research topics, problems or concepts in Classical Mechanics I'm fairly certain the volume will be comparable to all the random research topics and problems in QFT or string theory.

The point is you don't need to know more than 5% of string theory to do research, just like you don't need to know what a symplectic manifold is to do classical mechanics. I guess the difference is that most people can agree what the basics of CM are, but it's not yet clear for ST.

Knowing all string theory is like knowing all of History. Unpractical, unnecessary, most likely impossible.

 

[ImaLooser]

It's as if we discovered time dilation, but without Einstein ever being born.

Huh?

 

[Demystifier]

I agree with negru (and disagree with QGravity).

 

[scottbekerham]

I think (I don't know if it's true) that the most important skill one has to acquire in order to really understand strings is differential geometry and lie groups . Differential geometry is the basic tool to use as one deals with curved surfaces , branes and other geometric structures. Even gauge theory is best expressed using fibre bundles and connections . So you can't get far in string theory without differential geometry .What I want to know is :
Is it sufficient to understand differential geometry from a practical point of view (e.g. nakahara ) or should one learn the foundations of the subject (Which means absolute ragor) (e.g. read spivak textbooks on DG) in order to be able to apply these mathematical ideas in nonconventional and non-trivial way ?

 

[haushofer]

I would say that Nakahara is sometimes already to rigorous. Its treatment on Fibre Bundles and gauge theories is not really a revelation; I've never understood this fetish of some people with fibre bundles anyway.

So imho Nakahara suffices for most applications, unless you really want to do die-hard math. E.g., the proof that certain string theories are anomaly-free is rather involved, and I think that only reading Nakahara doesn't give a thorough understanding. On the other hand, I'm not sure how interesting that is unless you really want to be able to do the full calculation on your own.

 

[sshai45]

About experiment / theory argument, I would say making important experimental discoveries is as hard as making important theoretical discoveries, but the entry barrier is lower. Just look at how many undergrads help out in the labs.

In fact, once you get to the professional level, you're competing with people who have devoted a large part of their life to understanding the subject. It's hard to make truly groundbreaking contribution to any field. So my impression is that when people talk about a subject, e.g. string theory, being hard, what they're really saying is that the entry barrier is high.

So does this mean you can only be ready to compete after spending, say, 25-30 years (a "large part of your life") studying it?

 

[haushofer]

So does this mean you can only be ready to compete after spending, say, 25-30 years (a "large part of your life") studying it?

No, that's impossible. In that time the field already has involved in such a way that you should catch up again, creating some sort of Zeno paradox.

That's why people buy the book of Becker^2 Schwarz. It's horrible as a pedagogic introduction, but it gives a highly compressed overview of the field in less than 1000 pages. It allows people to get the overview which is needed to start research, even though it's more of a "knowing the jargon" than "understanding what's really going on".

One of the hard things about research in theoretisch physics, and string theory in particular, is that you have to find a midway between understanding and being able to contribute to the field. Most people, not being geniuses, will find the following: trying to understand too much does not allow you to contribute, and trying to dive into something very specific doesn't allow you to develop a broad overview and put your findings into the bigger picture. Which can become awkwardly exposed during questions if you give a talk :P