This video is from the YouTube channel 1veritasium and it’s about the world’s roundest object! The world’s roundest object helps solve the longest running problem in measurement — how to define the kilogram. This perfect cylinder is made out of a single crystal of silicon 28 atoms. By carefully measuring the diameter, the volume can be precisely specified. Since the atom spacing of silicon is well known, the number of atoms in a sphere can be accurately calculated. This allows for a very precise determination of Avogadro’s constant. Enjoy this video!
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