Within which time frame from the initial Big Bang do cosmologists believe all four fundamental forces of nature were united into a single force? A) t = 0 to 10⁶ years, when radiation dominated the universe B) t = 0 to 1 s, when photons interchanged freely with electron-positron pairs C) t = 0 to 10^-35 s, when the strong nuclear force "froze out" of the universe D) t = 0 to 10^-43 s, the Planck time, when gravity "froze out" of the universe

Question

Quizplus · Accepted Answer

The correct time frame is from t = 0 to $10^{-43}$ seconds, known as the Planck time, during which all four fundamental forces (gravitational, electromagnetic, strong nuclear, and weak nuclear forces) are believed to have been unified into a single force. This period marks the earliest phase of the universe immediately following the Big Bang, before gravity separated from the other forces.

Within Which Time Frame from the Initial Big Bang Do