What Everyone Ought To Know About White Hat
second unit of time Starting in the 1950s, atomic clocks became better timekeepers than Earth's rotation, and they continue to set the standard today. In science, a second is the time it takes for a caesium atom to vibrate 9,192,631,770 times. Scientists measure the second this way because the length of a day changes all the time. For example, when the dinosaurs lived, a day was about an hour shorter. Vibrations of atoms on the other hand always take the same time. The Earth's motion was described in Newcomb's Tables of the Sun , which provided a formula for estimating the motion of the Sun relative to the epoch 1900 based on astronomical observations made between 1750 and 1892. A consistent method of sending signals must be developed before the second is redefined, such as fiber-optics. The definition of a unit refers to an idealized situation that can be reached in the practical realization with some uncertainty only. In 1656, Dutch scientist Christiaan Huygens invente