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

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

#81

Post by idontpost »

snakeyjake wrote: post #72
TheDudeMan wrote: post #2

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

"Civilizations smart and advanced enough to collapse entire dimensions but too dumb to move past the need to compete for planets by parking themselves off to the side of a black hole and harvesting energy from its relativistic jets" is so stupid. Every time a seemingly intelligent person takes the dark forest hypothesis seriously I am dismayed. The only answer to the dark forest is: FTL is impossible and we are prese…

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

#82

Post by tombert »

staunton wrote: post #80
tombert wrote: post #75

It makes me a little sad, because we're in this frustrating position of knowing how "effectively unlimited" the universe is, but also knowing how impossible it is to realistically explore it, at least not without a fundamental change to our understanding of physics. I think it'd be cool to set up colonies on other planets, or hell, other solar systems, but the inability to communicate seems like a pretty hard blocker…

We have "enough time" to explore stuff. You or me will not live to see it but what's stopping a spaceship from going to some place for a few million years?

I mean, sure, in the scope of the universe then there's plenty of time before the heat death for some humans to explore another star system, they just won't really be able to communicate about it and relay back to us within a human lifetime really.

I'm just kind of hoping that physicists are all wrong, and that there turns out to be some fancy math that allows to do something faster than light. Not saying it's gonna happen that way, but a guy can dream.

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

#84

Post by spintin »

spintin wrote: post #15
isodev wrote: post #10

Earlier quoted context omitted.

I've seen a few "can't scale many-to-many" Java/C things in my career... it's all about how you put things together. I don't think Java and C can go faster than light either ;-).

The Java concurrency package is the only way to get your multi-core CPU to share memory atomically without going "Arrays of 64 byte atomic Structures" with C. And then you are in segmentation fault hell. Sun had to rewrite the entire JVM in 2003 with a new memory model, later adopted in C++11 (and still the current C++ memory model) which failed for C++ because this model only works well if you have a VM with GC. C#…

lol classic HN down vote without comment...

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

#85

Post by MPSimmons »

gaze wrote: post #51

I’ve been working on quantum computing and quantum communication for 15 years now and what I really want people to know is that entanglement is “beyond classical correlation.” Correlation which is not beyond classical is shaking up a shoebox with a pair of gloves in it, and having two people take the gloves far away from each other to then observe what hand they got. They then understand the hand the other has. There…

In my mind, I see it like you've got a line bisecting another line. You don't know what the angles are until you measure one, and once you measure it, you know for certain what the other angle is, whether that person does or not. But you can't change the angle and you can't send information using them.

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

#86

Post by d0mine »

gaze wrote: post #51

I’ve been working on quantum computing and quantum communication for 15 years now and what I really want people to know is that entanglement is “beyond classical correlation.” Correlation which is not beyond classical is shaking up a shoebox with a pair of gloves in it, and having two people take the gloves far away from each other to then observe what hand they got. They then understand the hand the other has. There…

Feynman explains quantum correlation using boxes with 3 buttons https://youtube.com/watch?v=ZcpwnozMh2U&t=17m55s

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

#87

Post by bilsbie »

gaze wrote: post #51

I’ve been working on quantum computing and quantum communication for 15 years now and what I really want people to know is that entanglement is “beyond classical correlation.” Correlation which is not beyond classical is shaking up a shoebox with a pair of gloves in it, and having two people take the gloves far away from each other to then observe what hand they got. They then understand the hand the other has. There…

Thanks. So how is it not analogous to the glove example?

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

#88

Post by leetharris »

joecarrot wrote: post #74

I read a book about particle physics and understood a very small amount of it. My understanding is that you cannot have faster than light anything because nothing can travel faster than light. For instance, the gravitational field of this coffee cup in my hand spans the entire universe. The cup is gravitationally attracting me, the Earth, the Sun, and every other atom in the universe (albeit at a remarkably low level…

The "speed of light" is actually a somewhat poor common name for the limitation.

It should be called the "speed of information."

If the sun somehow magically disappeared, we would continue to orbit that empty space for about 8 minutes.

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

#89

Post by rbanffy »

Workaccount2 wrote: post #27
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…

> _any_ interaction with anything counts as a "measurement" from the particles perspective.

"Measurement" is a terrible word we've been using, along with "observer".

What matters is information propagating from one system to another or, perhaps better, when the superposition has any external effect, then the superposition collapses and the system assumes a classical state.

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

#90

Post by MPSimmons »

joecarrot wrote: post #74

I read a book about particle physics and understood a very small amount of it. My understanding is that you cannot have faster than light anything because nothing can travel faster than light. For instance, the gravitational field of this coffee cup in my hand spans the entire universe. The cup is gravitationally attracting me, the Earth, the Sun, and every other atom in the universe (albeit at a remarkably low level…

Photons, like everything else, travel along the curvature of spacetime (though a physicist has told me that they do have some mass and thus warp spacetime themselves, too), and the speed of light is just how fast spacetime can curve. The faster you go, the more curved it is, and the harder it is to bend it further, but there's a point where you can't bend it any faster than you are because it doesn't go faster.
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