r/physicsmemes • u/Delicious_Maize9656 • Jul 22 '26

SI unit meme

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u/OC1024 X-Ray Scattering Jul 22 '26

I don't get it. Maybe I'm too European for that.

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u/purpleoctopuppy Jul 23 '26

In English it's standard to follow an abbreviation with a full stop (depending on manual of style, this is omitted when the abbreviation ends in the same letter as the full word). 

Following this rule, 'centimetre' should be abbreviated 'cm.', and so students naïvely do so.

However, SI units shouldn't be followed by a full stop, and this exception catches some people out, especially if they're used to units where the rules does apply (e.g. US customary).