unification explanation

Selnex

I am nearly certain that it has been suggested that three of the four now thought to be fundamental causes of motion have been unified. Excluding gravity, these are : the weak force, the strong force and electromagnetism. Can someone please explain to me what indicates or how it was shown that these three forces can shown to be unified and what it means that they are unified?

mathman

Actually only the weak and electromagnetic forces have been unified (electroweak force). The strong force plus the electroweak force form the Standard Model, in that they are compatible and both are quantum theories. Gravity, on the other hand, is described by General Relativity, which is a classical (non quantum) theory. There are certain extreme conditions (inside a black hole) where the two theories (quantum and G.R.) are incompatible. One of the major areas of current theoretical research is developing a theory to include all four forces. String theory is an example.

arivero

As for the meaning of unification, it depends of the theory. In a GUT, it means that all the carriers of force are classifyed in an unique mathematical scheme, usually a SU(n) group. In these schemes, forces seem to be different because of symmetry breaking: the carriers get different masses, thus different range of interaction.

LURCH

Mathman,
It is my understansing that the strong force has been linked recently. I'll double-check to make sure, though.

Selnex,
What is meant by uniwfication is that these three forces become identical at high enough energies. Mathematial models showed that everything the ellectromagnetic force does at these temps, the weak nuclear also does. At higher energies, the strong nuclear force also behaves the same way. These mathematical predictions were recently verified through experimentation. Verification of the gravitational foce (or proof that it will not unify) awaits a higher-energy supercollider.

dock

What's the purpose of unification then having in mind that it only referes to significant high energy?

I tought that unification should let us understand that every force no matter from what kind of interaction arized is at the bottom force or no matter electrical, magnetic, nuclear or gravitational in the end they are all forces. thus you can displace one by some other while exersizing your math and every thing to be ok with that.

Could I practise this kind of independent thinking without problems?