Final answer:
The first force to separate from the unified single force during the Big Bang was gravity. After gravity, the strong nuclear force separated, and finally, the electroweak force split into the electromagnetic and weak nuclear forces.
Step-by-step explanation:
At the very beginning of the Big Bang, when the universe was extremely hot and dense, all of the fundamental forces (strong nuclear, electromagnetic, weak nuclear, and gravitational) were unified, behaving as one single force. As the universe expanded and cooled, these forces began to "freeze out" or separate from each other. The first force to separate was gravity, after which the combined strong nuclear and electroweak forces existed. Following this, the strong nuclear force separated from the electroweak force. According to the Grand Unified Theories (GUTS), as the universe continued to cool down, the electroweak force then split into the electromagnetic force and the weak nuclear force, becoming distinct entities as we observe them today. The gravitational force is particularly challenging to unify with the other forces due to its unique effect on space and time. In summary, the first force to freeze out as a separate force during the Big Bang was gravity.