The Planck time is
A) the time it takes for light to travel across-- or around-- the entire universe.
B) the time when the cosmic background radiation originated.
C) the time it takes for an electron in an unexcited hydrogen atom to orbit the nucleus one time.
D) the time required for pair creation.
E) the shortest time that has any physical meaning.

Question

Quizplus · Accepted Answer

Planck time is the smallest measurable unit of time, defined as the time it takes for light to travel one Planck length. It represents the limit below which the laws of physics as currently understood cease to be useful.

The Planck Time Is