According to the Big Bang theory, how many forces operated in the universe during the GUT era?

The correct understanding of the Big Bang theory and the associated GUT (Grand Unified Theory) era indicates that during this phase of the universe's evolution, it is hypothesized that three of the fundamental forces—specifically the strong nuclear force, the weak nuclear force, and electromagnetic force—were unified into a single force.

During the GUT era, which is a brief period that occurred at approximately (10^{-36}) to (10^{-32}) seconds after the Big Bang, the universe was extremely hot and dense. The energies were so high that the distinctions between these three forces became negligible, meaning that they operated as a unified force. Gravity, however, is treated differently in theories of quantum gravity and did not unify with the other three forces at this time, remaining a distinct force.

Thus, stating that there were two forces—gravity and a single unified force—does not accurately reflect the current understanding of the unification of the forces during the GUT era. While gravity was present, the focus is on the unification of the strong, weak, and electromagnetic forces into one single force, making it clear that the correct interpretation accounts for the three forces unifying rather than standing apart as gravity does.