zeptometer

A zeptometer is a unit of length in the metric system, equal to 10^−21 meters. It is the smallest unit of length in common use. The prefix "zepto" comes from the Latin word "septem," meaning seven. A zeptometer is one sextillionth of a meter.

To put the zeptometer into perspective, it is extremely small. For example, the diameter of a proton is approximately 0.84 zeptometers. The size of an atom is typically in the range of tens of picometers, where a picometer is 10^−12 meters. Therefore, a zeptometer is vastly smaller than an atom.

The zeptometer is used in particle physics and other fields where extremely small distances are studied. It is a very specialized unit and is not commonly encountered in everyday life. While theoretical physics may explore even smaller scales, the zeptometer represents a practical limit for current scientific measurement and theory. The smallest directly measured distances are in the attometer range, and the zeptometer is a theoretical extension of this scale.