Is there like a master ruler? Who decided what a length a cm, mm and inch would be and why?
In: Other
Actually, yes!
For example, the kilogram was originally defined in 1795 during the French Revolution as the mass of one litre of water. In 1799 they decided that everyone would refer to a single platinum block as THE definitive kilogram, and copies were based on this example.
Likewise, machinists who need standardized lengths can resort to gauge blocks. It’s a little suitcase full of metal or ceramic bricks that have been cut to an absolutely ridiculous degree of precision (0.05 micrometers). They are so perfectly flat that if you press two of them together the individual atoms will start to behave as if they are one solid object and you have to exert force to break them apart.
Latest Answers