Grand unified theories

Grand unified theories (GUT's), theories that attempt to explain the physical universe by a unified concept of 3 of the 4 fundamental forces: the weak nuclear force, which controls radioactive decay of atomic nuclei; electromagnetism, which secures the electrons to the nucleus; and the strong nuclear force, which ties the nucleus together. The fourth fundamental force, gravitation, has not yet been included in GUT's. It is not known if it is indeed possible to explain all events and phenomena of the universe in such a unified manner.