How do we know that the fundamental forces become unified as the energy of particle interactions increases?

Question

Hazel Asher · Accepted Answer

Two of the fundamental forces have already been proved to unify at high energies.

According to the standard model of particle physics, boson particles are responsible for the fundamental forces' interactions. The photon, a boson, is the particle that propagates the electromagnetic force. The two bosons that make up the weak nuclear force are the W, a charged particle that is involved in the process of converting a quark from one flavor to another; this is what leads to beta decay, in which a neutron is converted into a proton, an electron, and an electron antineutrino. The Z boson is involved in the process of neutrinos being scattered off other particles. The two forces can be mathematically described by symmetry groups; the discovery of the W and Z allowed for the unification of electromagnetism and the weak force into the electroweak theory by establishing a unifying symmetry group that demonstrates the indistinguishability of the photon and the Z boson at high energies. The strong nuclear force is essentially a residual effect of the color force, and the next step is to find a Grand Unified Theory (GUT) that unifies the electroweak force and the color force that binds quarks together. Candidate GUTs require additional particles that we haven't yet discovered, and there are several candidate theories for a GUT. The problem is that the unification energy is so high that we can't imagine how to build a particle accelerator to reach it. A GUT will probably be discovered, but not anytime soon. There is a serious issue with gravity since there is no quantum theory of it. New physics is needed to create a Theory of Everything that unifies the four forces. String theory may be the solution, but it will take some time to develop.

Leah Abbate · Answer

undefined The unification of fundamental forces is theorized through Grand Unified Theories (GUTs) and the Standard Model. As energy increases, forces appear similar, suggesting a common origin. Experimental evidence includes particle interactions at high energies showing behaviors consistent with unified force theories.