Reply to post: how do you measure a change of 1/10,000 of a proton diameter with a laser?

Boffins' gravitational wave detection hat trick blows open astronomy

PghMike

how do you measure a change of 1/10,000 of a proton diameter with a laser?

Optical lasers wavelengths are in the few thousands of angstroms (angstrom = 10^-10 meters). But a proton is 10^-15 meters in diameter, and 1/10,000 of that is 10^-19 meters, or one billionth of a photon of visible light.

So, how can you use such large photons to see such a small change in length?

Also, how do you know the size of the black holes involved, at such a distance?

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