
Quantum entanglement and the non-orientability of spacetime - ovidiu69
https://arxiv.org/abs/2009.04990
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codethief
I know this is a physics paper and not a math one but as a mathematical
physicist / relativist I find it very confusing that you treat "orientability"
and "time-orientability" as synonyms. These are completely different concepts,
though, see e.g.

[https://physics.stackexchange.com/questions/14168/orientabil...](https://physics.stackexchange.com/questions/14168/orientability-
of-spacetime)

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charlieflowers
Well, I read the abstract, but I must admit it didn't help me at all :shrug:

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meowface
It appears the OP of this thread is the author of the paper, for what it's
worth, so if anyone could summarize it it would probably be them.

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vondur
Yeah OP, come and give us the layman's version of Quantum Entanglement! (If
that is indeed possible)

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ahelwer
I'll give it a shot. When you entangle two particles, it's kind of like
they're connected to the same random number generator. So if you measure one
particle it'll collapse to a certain value (at random), and you know that the
other one will also collapse to the same value (or some other such
correlation, depending on how you set up the entanglement). You also
definitely absolutely cannot use entanglement to communicate information.

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cellular
The way you described it, it seems like it could relay information: If you see
an odd value, meet me at Disney world. If you see an even value, meet me at
the grand canyon. This way, our persuer won't know where we will meet.

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ahelwer
Well, it relays information in the same way that each of you using a random
number generator pre-initialized with the same seed relays information. It
doesn't involve faster-than-light communication, is the point. Entanglement
differs from classical RNGs in that there is no shared seed; no local hidden
variable, as it's called. The measurements are just... correlated. If you're
interested in a deep dive on entanglement I wrote a post about it:
[https://ahelwer.ca/post/2018-12-07-chsh/](https://ahelwer.ca/post/2018-12-07-chsh/)

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nzd
This is hard to fully understand. So you can't choose in any way which state
it will collapse to during measurement? If that was possible, it would mean
FTL communication I guess.

