Electroweak Unification Theory

There are four fundamental forces of nature;

1. The Strong Force

2. The Electromagnetic force

3. The Weak Force

4. Gravity

Right after the Big Bang, when the temperature of the universe was too high, all of these forces were in a combined form like in the form of a Super Force. As the universe cooled, the electroweak epoch (period after big bang when temperature was high enough for electromagnetic force and weak force to remain unified but not enough for strong force to remain in unification so strong force got separated) ended, temperature further fell down and quark epoch started, and hence they got separated forming electromagnetic force and weak force.

(It is all about showing that all of these fundamental forces were once unified)

Abdus Salam. Weinberg and Glashow in 1979 showed unification of these two forces and later in 1983,it was experimentally verified after the discovery of W and Z bosons.

Now, unifying or combining all of the fundamental forces (Grand unification) requires a temperature of 10^27 K which is currently unachievable.