yoctometer

Yoctometer is the SI unit of length equal to 10^-24 meters. It uses the prefix yocto-, designated by the symbol y, which represents 10^-24. The yoctometer is commonly cited alongside other SI prefixes but is rarely used in everyday measurements due to the extreme smallness of the scale. A yoctometer is one thousandth of a zeptometer (10^-21 m) and one millionth of an attometer (10^-18 m).

The concept of such a small length arises chiefly in theoretical and high-energy physics discussions rather than in practical metrology. Direct experimental measurement at the yoctometer scale is beyond current instrumentation. In many contexts, physicists describe extremely small distances using natural units, where length can be expressed in inverse energies, rather than in meters.

In relation to other fundamental scales, the Planck length is approximately 1.6 × 10^-35 meters, about 10^11 times smaller than a yoctometer. This illustrates that the yoctometer sits well above the smallest conceivable lengths suggested by some theories, yet far below scales accessible to direct measurement with conventional techniques.

Summary points: a yoctometer is 10^-24 meters, symbol ym; it is the smallest officially recognized SI length prefix, and its practical use is largely confined to theoretical discussions about ultra-small distances in physics.