The beard-second is a unit of length inspired by the light year, but used for extremely short distances such as those in nuclear physics. The beard-second is defined as the length an average physicist's beard grows in a second. Kemp Bennet Kolb defines the distance as exactly 100 Ångströms[1] while the Physics Handbook has it half the size at 5 nanometers.[2] Google search supports the beard-second for unit conversions using the latter conversion factor.[3]

the true length of the beard second growth is unknown because it varies due to certain quantum events such as particles appearing from nowhere or diverging from themselves causing major changes in its measurement