What good is string theory?

[rrw4rusty]

Hi!

 

When quantum mechanics was established it allowed us to do things that we could not do before.

 

What would string theory allow us to do? Lets say that string theory was confirmed -- tests showed the projections string theory made were correct and now string theory was accepted. What would it allow us to do that we can't do now? What good would it do us?

 

Thanks,

Rusty

[ajb]

What it has done so far include

 

1) A calculation of the entropy of black holes based on statistical/quantum physics.

2) Related gravity and gauge theory by the KLT relations. (Which has since been shown to hold more generally).

3) It was the first (only?) theory to make a prediction of the number of dimensions.

4) It predicts gravity. The graviton is necessarily in the closed string spectrum.

5) Suggests that space-time should have a discrete nature (string momenta).

 

On the mathematics side it has been instrumental as a motivation for many investigations in geometry and topology. For example mirror symmetry has a "stringy conception". String theories on different Calabi-Yau manifolds are identical and this lead to its discovery.

 

It can be difficult to distinguish string theory properties and supersymmetric field theory properties. lot of string theory deals with the low energy effective theories. Supersymmetry has also had a large impact on mathematics. Seiberg-Witten and Gromov-Witten invariants are good examples as is Witten's proof of the Morse inequalities.

 

Both string theory and SUSY theory allow many physical ideas to enter pure mathematics. This is very much a benefit to both mathematics and physics.

 

What would sting theory like to do is more involved. Ideally, string theory (or some think like M-theory etc) should allow us to unify the forces and have only one free parameter.

 

Probably string theories greatest achievements could be in the field of cosmology and astrophysics as we would have an understanding of quantum gravity in extreme conditions.

[J.C.MacSwell]

Why is String Theory considered a Theory in the scientific sense. Or is it?

 

Seems premature as it has not been solved/confirmed.

[ydoaPs]

Hi!

 

When quantum mechanics was established it allowed us to do things that we could not do before.

 

What would string theory allow us to do? Lets say that string theory was confirmed -- tests showed the projections string theory made were correct and now string theory was accepted. What would it allow us to do that we can't do now? What good would it do us?

 

Thanks,

Rusty

 

[ajb]

Why is String Theory considered a Theory in the scientific sense. Or is it?

 

Seems premature as it has not been solved/confirmed.

 

You should take theory to mean an mathematical model or framework.

 

Think of string theory as a mathematical set-up that possibly could be used to construct realistic theories of nature.

[J.C.MacSwell]

You should take theory to mean an mathematical model or framework.

 

Think of string theory as a mathematical set-up that possibly could be used to construct realistic theories of nature.

 

It just seems to me it is more "string conjecture" at this point. In a scientific sense it really hasn't met the criteria that other scientific theories have, such as Relativity, Evolution, or even the Big Bang.

[ajb]

It just seems to me it is more "string conjecture" at this point. In a scientific sense it really hasn't met the criteria that other scientific theories have, such as Relativity, Evolution, or even the Big Bang.

 

Theory in a more mathematical sense means "a collection of knowledge".

 

Let us take an example you have given.

 

General relativity by itself is not enough to describe nature. It is a mathematical framework in which to describe nature. Even with certain energy conditions you have lots of solutions which may or may not be physically realised.

 

String theory should be viewed in the same way. It gives a mathematical framework in which to work. It may, or may not be the correct one to give a unification scheme and describe nature well.

 

This is the same as quantum field theory, quantum theory, classical dynamics, thermodynamic theory etc...

 

All need extra work in order to build a "physical theory".