what are pridictions of string theory.?

Answer 1

11 dimensional string theory, (and 26 dimensional M theory), has not produced anything.

It is possible that the extra 7 dimensions of space in string theory, (that are not perceived), are mathematical deception that first appeared with 5 dimensional Kaluza-Klein Theory.

String theory is possibly deception involving adding dimensions of space to the already existing 3 dimensions of space one dimension at a time at 90 degree angles to the previous dimension.

That string theory is possibly invalid is stated at the end of the wikipedia article on string theory.

Answer 2

First, string theory is a hypothesis; not a theory even though that's what it is called. It is a hypothesis because it is yet to be tested by a controlled falsifiable test, which is a prerequisite to be called a theory.

Second, here are some of the WAGs I remember:

* Everything is made of infinitely thin vibrating strings of 1 Planck length (about !0^-33 cm).

* How these strings appear in our universe depends solely on the frequency of the strings.

* Strings can be mass (like bosons) or massless (like photons) in our universe.

* The perturbation equations used to predict the string characteristics reach into 10, 11, or more dimensions, depending on which string theory you invoke (there are more than one).

* Parallel universes may exist in other dimensions next to our own, something like slices of bread in a meta-universe loaf.

* The big bang may have been caused by a collision between two or more parallel universes; in which case, the BB occurred in more than our own universe.

* Some strings may co-exist in other universes as well as our own. The strings that predict the graviton, for example, are among this kind of strings.

Read "The Elegant Universe" and "The Fabric of the Cosmos" by Brian Greene, Ph.D., Columbia U. He also has an excellent, easy to read web site.

Answer 3

To make a long story short, one of the main problems of string theory is that it cannot predict anything measurable. This is actually why it's not so fashionable nowadays, though some great minds think it holds remarkable promise.