It can be local in many-worlds.
http://lesswrong.com/lw/q1/bells_theorem_no_epr_reality/ http://lesswrong.com/lw/q2/spooky_action_at_a_distance_the_n...
Quantum entanglement shows that reality can't be local
141–150 of 172 posts
Re: Quantum entanglement shows that reality can't be local
#142Earlier quoted context omitted.
The most interesting question to me is - what happens when one of the entangled particles get annihilated. If the other one does too, instantly, then we can use that to communicate faster than light.
No. If you annihilate one of the particles, the other particle continues "unaffected". Whatever you do to one of the particles, the other particle continues "unaffected". Quantum mechanic is a little more complex, so it is difficult to explain what "unaffected" really means. It's clearer with an example. Let's suppose that you and I have each one a particle that is a half of an entanglement particle pair: * If you do…
Hmm, this somehow defies common sense (but of course, its quantim mechanics, so thats a given!).
You are saying that, if theres an entangled pair, they cannot be used to transmit information that couldn't be otherwise transmitted via "conventional" means. However, if you performed the measurements, and then compared notes you will find that somehow, it looks like the measurements were "synced"?
How does it work this way? that is, how could it be the case that those measurements can be related, but you can't use that relation to transmit informatino?
Re: Quantum entanglement shows that reality can't be local
#143It can be local in many-worlds. http://lesswrong.com/lw/q1/bells_theorem_no_epr_reality/ http://lesswrong.com/lw/q2/spooky_action_at_a_distance_the_n...
Looks like you're a firm believer, so I ask, is MWI by your definition falsifiable?
Do any experiments past, current or future purport to test predictions made from MWI?
While MWI may make sense in a universal reading of QM, I'm not sure we can simply extrapolate this onto the macro level, despite it's pragmatic successes over the last century. IMHO QM itself, still feels like a temporary hack (shim), when compared alongside ER.
Until we have a TOE, it may be too presumptuous to be making positive assertive claims on the correlation between the MWI model and reality.
Re: Quantum entanglement shows that reality can't be local
#144This is for me the most interesting part of the whole teleportation / entanglement research. When these papers started coming out we debated the notion of 'faster than light' communication. The counter argument was that you had to move the particles apart and that was constrained by the speed of light. Then the question of "when" the state was resolved was pondered. There were two thought experiments proposed at this…
and have the alien equivalent of the FCC come out to the planet to arrest the scientists for transmitting without a license Or the channel is already filled completely with spam.
Or filled with get rich quick scams. That reminds me of a Charles Stross novel, I think Accelerando.
Re: Quantum entanglement shows that reality can't be local
#145Earlier quoted context omitted.
Let me try to explain myself better: Two particles are entangled and separated by a vast distance. At some point, I conduct a measurement on the first particle, causing me to split into two different versions of myself that have measured two different states. Now, the effect of that measurement spreads outwards from the site of the measurement, so I may affect other things based on the measurement, etc. My problem is…
> My problem is that if a measurement is done on the other particle, long before any message from me could possibly have got there, then that measurement and the effects it has on its local environment and the effects they have are all also dependent on my measurement. Imagine that your friend Joe writes the same word on two pieces of paper, puts them in envelopes and hands one envelope to you and mails the other env…
That's a hidden variable theory.
Re: Quantum entanglement shows that reality can't be local
#146Earlier quoted context omitted.
Let me try to explain myself better: Two particles are entangled and separated by a vast distance. At some point, I conduct a measurement on the first particle, causing me to split into two different versions of myself that have measured two different states. Now, the effect of that measurement spreads outwards from the site of the measurement, so I may affect other things based on the measurement, etc. My problem is…
then that measurement and the effects it has on its local environment and the effects they have are all also dependent on my measurement. I think that's your trouble there. Those are totally independent of your measurement, the waveform splits at the measurement of the other particle the exact same way, regardless of what happened to you locally.
except I can never be in a universe where it split at my measurement site in one way and it split at the other measurement site the other way. That means that I am entangled with a measurement that happens nonlocally to me and everything that it interacts with.
Re: Quantum entanglement shows that reality can't be local
#147Having read this very carefully, I can't see how quantum mechanics as I always understood it can ever be either non-local or break relativity. The following was probably written down by someone else a long time ago, but I don't know by who or when.
When you entangle two systems, they have to actually be in the same place/with slower-than-light communication distance. Thus, they each store "secret" information in some deterministic way which is impossible to measure directly, and which we can probe only using repeated experiments and probability distributions. The idea is that while quantum systems are deterministic just like mechanical ones, they hide their determinism in black boxes whose mechanisms it is impossible to discover. The "uncollapsed waveform" has in fact been collapsed ahead of time, you just don't know what the answer is until you measure.
Back to our entangled particles, when you separate them the determined decision they made when they were together is revealed. They do not need to communicate, as they already have their story straight.
It seems this entire area of research is a misnomer - if you let the prisoners talk to each other just after arrest, of course their stories will be complimentary later, even if one is in Alcatraz and the other in Siberia. You just have to assume that particles so small we can only "see" them in the way they interact with other particles have some internal structure/state that we also can't see, and thus like the prisoners, can remember the story.
(of course, declaring an entire area of research irrelevant is usually a sign that I've missed the point wildly - if anyone would like to correct my mistake I'd be interested to hear!)
Re: Quantum entanglement shows that reality can't be local
#148Earlier quoted context omitted.
and have the alien equivalent of the FCC come out to the planet to arrest the scientists for transmitting without a license Or the channel is already filled completely with spam.
Or filled with get rich quick scams. That reminds me of a Charles Stross novel, I think Accelerando.
That should be a quest in some space exploration game. You research hiperspace radio, then you decode alien languages, then you get mysterious quest involving intergalactic wars, lost artifacts and last scions of ruling families. You duly follow the leads to learn more about these subjects, find that nothing seems to check up, only to find out at the end that it was just Nigerian scam.
Re: Quantum entanglement shows that reality can't be local
#149Earlier quoted context omitted.
then that measurement and the effects it has on its local environment and the effects they have are all also dependent on my measurement. I think that's your trouble there. Those are totally independent of your measurement, the waveform splits at the measurement of the other particle the exact same way, regardless of what happened to you locally.
except I can never be in a universe where it split at my measurement site in one way and it split at the other measurement site the other way. That means that I am entangled with a measurement that happens nonlocally to me and everything that it interacts with.
You're not entangled with the measurement, you're entangled with the entire wave despite the inconceivable number of measurements that happen within it. The same way my friends are still my friends despite us being in different places. I won't know instantly if they die or something, but I react differently when I hear about what happens to them than I do with ordinary people. If one of them gets into a car accident outside my light-cone and I'm more sad when I hear about it than about the car accident of a stranger, that doesn't mean that I have a non-local interaction with the car accident.
Re: Quantum entanglement shows that reality can't be local
#150Earlier quoted context omitted.
I didn't realize that Ursula Le Guin coined that term. My first recollection of it was from Orson Scott Card and later, Dan Simmons. In any event, entanglement certainly doesn't look like it will lead to an ansible yet.
Yea, my first encounter was in Ender's Game. :)
I loved that book as a kid. It looks like they are finally going to release the movie version in a year from now. They've been teasing us with movie announcements for the better part of a decade.
I wonder if they'll directly mention quantum entanglement?