Everybody measures light at the same speed

Measure a light beam and you get 299,792,458 m/s — standing still, running

Why it works

If light’s speed cannot differ between observers, then the things used to

Do it exactly

Estimate with the rule, then check it against the calculator that models it properly.

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What is relativity, in one sentence?

Measure a light beam and you get 299,792,458 m/s — standing still, running If light’s speed cannot differ between observers, then the things used to .

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