Although the 4 forces seems to have very different nature (for example, their strength and the gauge bosons corresponding to the forces are different), physicists have found that, as the energy of the gauge bosons (can think of as A and B throwing the ball faster), increased, the strength of the strong force and weak force will decrease while the strength of the electromagnetic force will increase. Therefore, it is natural to think that their strength will be the same at some high enough energy and the 3 forces will then become indistinguishable. This idea is called the Grand Unification Theory (GUT). Unfortunately, gravity does not seem to be unifying with the other forces. The idea of Electroweak Unification was suggested before GUT, which only says that electromagnetic force and weak forces will be unified and become indistinguishable at some energy lower than the one needed to unify the 3 forces.