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Why quantum entanglement doesn't allow faster-than-light communication (2016)

forbes.com

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Re: Why quantum entanglement doesn't allow faster-than-light communication (2016)

#21

Post by bowsamic »

jemmyw wrote: post #18
bowsamic wrote: post #7

Earlier quoted context omitted.

> I accept that this coin-hypothesis has been disproved by people who actually knows what they're talking about. The classical idea is more like as follows: you have a guy Charles who makes two letters each with a card in that has written on it either number 0 or 1, and gives one letter to Alice and another to Bob. Now, "entanglement" here is that if Charles writes 0 in Alice's letter he writes the number 1 in Bob's,…

> Bell's theorem says you either need to give up the idea that there is no "spooky action", or give up determinism Can you not also say that the determinism includes the observer, aka superdeterminism (which is just determinism because that would surely be global).

This quote from my post

> or you can retain both if you let go of another concept called statistical independence.

is superdeterminism

Re: Why quantum entanglement doesn't allow faster-than-light communication (2016)

#22

Post by snapcaster »

euroderf wrote: post #5
TheDudeMan wrote: post #2

"3 Body Problem" has so many problems! Wake me up when the next "Expanse"-level sci-fi lands.

That precisely is so much of the appeal of The Expanse ! For getting around our solar system, take plausible, foreseeable tech and add just a bit of secret sauce (the Epstein drive). So,.. the evolutionary path of society as depicted in the series is plausible.

I wanted to like it so badly but the show just didn't hook me. Need to give it another chance sometime

Re: Why quantum entanglement doesn't allow faster-than-light communication (2016)

#23

Post by tsimionescu »

vjerancrnjak wrote: post #12
bowsamic wrote: post #7

Earlier quoted context omitted.

> I accept that this coin-hypothesis has been disproved by people who actually knows what they're talking about. The classical idea is more like as follows: you have a guy Charles who makes two letters each with a card in that has written on it either number 0 or 1, and gives one letter to Alice and another to Bob. Now, "entanglement" here is that if Charles writes 0 in Alice's letter he writes the number 1 in Bob's,…

Yes, Bell's theorem is such a strong result. 1. locality 2. (local) reality 3. statistical independence Only 2 can hold at once and there's consensus to have 1. and 3., with that we lose the hidden variables. Instead, having 1. and 2. hold would be so interesting.

In some sense, MWI also gets rid of 3, though it's not commonly seen like that. Essentially in MWI any experiment has all possible results, so the concept of statistical independence jsut doesn't make sense.

Either way, MWI is by far the most popular interpretation that is both local and realistic.

Re: Why quantum entanglement doesn't allow faster-than-light communication (2016)

#24

Post by ngcc_hk »

bowsamic wrote: post #7
mrkeen wrote: post #3

The gap I still have in my understanding: One hypothesis is that there is no spooky action. One particle was 'always' going to resolve one way, likewise with the other. Like inspecting 'heads' on one side of a coin 'forces' 'tails' onto the other side. I accept that this coin-hypothesis has been disproved by people who actually know what they're talking about. But to me, this implies that you should build your spooky…

> I accept that this coin-hypothesis has been disproved by people who actually knows what they're talking about. The classical idea is more like as follows: you have a guy Charles who makes two letters each with a card in that has written on it either number 0 or 1, and gives one letter to Alice and another to Bob. Now, "entanglement" here is that if Charles writes 0 in Alice's letter he writes the number 1 in Bob's,…

The key difference, unlike the usual sock example or your letter example, it is not about knowing. The superimposed quantum states have not been fixed. It is both colour or or letters or states at the same time all the time unlike it is measured. It is not the knowledge about a pre-existed, the individual state does not exist until measurement. That is the crazy part.

Re: Why quantum entanglement doesn't allow faster-than-light communication (2016)

#25

Post by yetihehe »

elcritch wrote: post #11
mrkeen wrote: post #3

The gap I still have in my understanding: One hypothesis is that there is no spooky action. One particle was 'always' going to resolve one way, likewise with the other. Like inspecting 'heads' on one side of a coin 'forces' 'tails' onto the other side. I accept that this coin-hypothesis has been disproved by people who actually know what they're talking about. But to me, this implies that you should build your spooky…

> One hypothesis is that there is no spooky action. One particle was 'always' going to resolve one way, likewise with the other. Like inspecting 'heads' on one side of a coin 'forces' 'tails' onto the other side. > I accept that this coin-hypothesis has been disproved by people who actually know what they're talking about. The quantum erasure experiment is to my mind the best example of the spooky action at a distanc…

Calling it "action" may be a mistake. Action implies something changes (there is a state called "before" and state called "after"). But nothing changes "over there", we just now know what actually happened (there is no state called "before" or it's value is "unknown", only state called "after").

Re: Why quantum entanglement doesn't allow faster-than-light communication (2016)

#26

Post by yetihehe »

dist-epoch wrote: post #19
mrkeen wrote: post #3

The gap I still have in my understanding: One hypothesis is that there is no spooky action. One particle was 'always' going to resolve one way, likewise with the other. Like inspecting 'heads' on one side of a coin 'forces' 'tails' onto the other side. I accept that this coin-hypothesis has been disproved by people who actually know what they're talking about. But to me, this implies that you should build your spooky…

> you'd need to be unable to distinguish between a measured/unmeasured particle This is true. There is no way to tell if a measurement you do happened on an entangled particle or on a "free" one. You can only tell in retrospect, when you correlate results, which requires classical communication.

So it can't be called "action"? Could be also described as correlation is not causation and action implies causation.

Re: Why quantum entanglement doesn't allow faster-than-light communication (2016)

#27

Post by Workaccount2 »

mrkeen wrote: post #3

The gap I still have in my understanding: One hypothesis is that there is no spooky action. One particle was 'always' going to resolve one way, likewise with the other. Like inspecting 'heads' on one side of a coin 'forces' 'tails' onto the other side. I accept that this coin-hypothesis has been disproved by people who actually know what they're talking about. But to me, this implies that you should build your spooky…

You cannot tell if a particle has been measured or not without...measuring it.

The key to understanding this is that _any_ interaction with anything counts as a "measurement" from the particles perspective.

I like to think that our simulation has a bandwidth compression algorithm that only decodes the state of a particle when it needs to calculate an interaction. Just like how your dungeon crawler doesn't spawn mobs until they are within interaction distance. But that's just fun head canon.

Re: Why quantum entanglement doesn't allow faster-than-light communication (2016)

#29

Post by youlweb »

Can we simply tell that the entanglement was collapsed on the other end? That would be sufficient to transmit information. If planet x is habitable when I get there, I measure/collapse this specific particle, whose counterpart is back on earth in a detector named "habitable". When the detector fires on earth because this particle was measured/collapsed on planet x, people on earth know planet x is habitable. There's no need to know the outcome of the measurement, just the fact that it was measured/collapsed is information enough.

Re: Why quantum entanglement doesn't allow faster-than-light communication (2016)

#30

Post by gaze »

youlweb wrote: post #29

Can we simply tell that the entanglement was collapsed on the other end? That would be sufficient to transmit information. If planet x is habitable when I get there, I measure/collapse this specific particle, whose counterpart is back on earth in a detector named "habitable". When the detector fires on earth because this particle was measured/collapsed on planet x, people on earth know planet x is habitable. There's…

We can’t.
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