# B Can someone explain string theory?

1. Aug 20, 2015

### Armando Valle

Can someone explain string theory? and how it works please? im really interested thanks :D

2. Aug 20, 2015

### Student100

There's are several different things that could fall under the umbrella of string theory. The different models don't "work", they just are. Can you elaborate more?

Judging from your post in the academic section, you probably will have difficulty grasping anything said here.

3. Aug 20, 2015

### Greg Bernhardt

4. Aug 21, 2015

### Demystifier

Last edited by a moderator: May 7, 2017
5. Aug 25, 2015

### Urs Schreiber

The single best way to conceptually understand what perturbative string theory really is about and why it is a natural concept to consider, is to first understand that ordinary perturbative quantum field theory has an equivalent formulation that is called the worldline formalism. In this formulation each Feynman diagram appearing in the computation of the S-matrix is identified with the correlator of a 1-dimensional quantum field theory, namely with the worldline theory of the first quantized particles that are the given quanta.

This worldline formalism in itself is highly interesting, as it is this formulation that most directly connects quantum field theory to zeta function regularization and hence to the mathematics of zeta functions and hence to structures famous in number theory. But for the purposes of the present question, of course the following aspect is relevant:

If the perturbation series of a quantum field theory is the sum over all appropriate 1-dimensional graphs of the correlators of a 1-dimensional worldline field theory, then...
...is there a generalization of this where one instead does a sum over d-dimensional spaces of the correlators of a d-dimensional worldsheet theory, as this is an immediate generalization?

And the answer is that doing this for d > 2 seems to be impossible. Doing it for d = 2 gives perturbative string theory.

More exposition that presents string theory along these lines is in

6. Aug 27, 2015

### Staff: Mentor

Closed pending moderation

Edit: a whole lot of off topic posts were removed, and the thread will remain closed

Last edited: Aug 27, 2015