Any theory which explains the
strong nuclear force, the
weak nuclear force the
electromagnetic force and
gravity as different aspects of the same
superforce. Theorised to have been present in the universe only during the
Planck time. Following this, gravity immediately became independent of the other three. These other forces continued to function as the
grand unified force until later in the history of the
universe , when they too separated, in stages, into the forces we know today.