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Old 2019-06-23, 06:40   #8
CRGreathouse's Avatar
Aug 2006

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Originally Posted by jasong View Post
Why can't quantum entanglement be used for speed of light communication or slower?

I tried to ask Google, but it appears to be obsessed with FTL communication, which I know is impossible.

What if we use double quantum entanglement, one over the long distance and one entanglement locally, where we are, and don't check the information until a photon would have had time to make the trip?
Fundamentally, when you and a partner have a collection of entangled particles, you don't communicate information when you both measure them. Rather, you both get (in essence) the same copy of noise/static/etc. So it's as instant as you like, but it doesn't convey information, thus circumventing the ban on speed-of-light transmission. Waiting longer doesn't somehow make the particles transmit information: they'll still just show noise, like they always do. (Indeed, if you measure them without entangling them you'll get the same sort of noise.)
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