title: Unit of time
context: The jiffy is the amount of time light takes to travel one fermi (about the size of a nucleon) in a vacuum. Planck time is the time light takes to travel one Planck length. Theoretically, this is the smallest time measurement that will ever be possible. Smaller time units have no use in physics as we understand it today. The TU (for Time Unit) is a unit of time defined as 1024µs for use in engineering. The Svedberg is a time unit used for sedimentation rates (usually of proteins). It is defined as 10−13 seconds (100 fs). The galactic year, based on the rotation of the galaxy, and usually measured in million years.[2] The geological time scale relates stratigraphy to time. The deep time of Earth’s past is divided into units according to events which took place in each period. For example, the boundary between the Cretaceous period and the Paleogene period is defined by the Cretaceous–Paleogene extinction event. The largest unit is the supereon, composed of eons. Eons are divided into eras, which are in turn divided into periods, epochs and ages. It is not a true mathematical unit, as all ages, epochs, periods, eras or eons don't have the same length; instead, their length is determined by the geological and historical events that define them individually.
question: What is the smallest unit of time?
answers: Planck time