1 Light-Nanosecond Ruler https://www.physicsfunshop.com/search?keywords=nanosecond The speed of light is a universal physical constant and the basis of this ruler, made 29.98cm in length and equal to the distance light travels in one billionth of a second. This amazing ruler, marked off in increments of 10 light-picoseconds, was created by Michael Stevens and came to me in The Curiosity Box by Vsauce last month. The photons of light from the “Inq the octopus” enamel pin take approximately 1 nano