Also known as Grand Unification or GUT, this refers to any of several unified field theories that predict that at extremely high energies (such as occurred just after the Big Bang), the electromagnetic, weak nuclear, and strong nuclear forces are all fused into a single unified field. Thus far, physicists have only been able to merge electromagnetism and the weak nuclear force into the “electroweak force”. Beyond Grand Unification, there is also speculation that it may be possible to merge gravity with the other three gauge symmetries into a “theory of everything”.