Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

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

forbes.com

Post reply on HN
Print view View original

91–100 of 166 posts

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

#91

Post by Jensson »

MPSimmons wrote: post #85
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.

Except the line is spinning around faster than you can see and you measuring it makes it stop. Your example makes it sound like the angle was decided before you measured.

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

#92

Post by ynniv »

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…

My understanding is that it's like two of the same scratch-off lottery ticket. There are two spots you can scratch, only one has a prize, we don't know which one that is but it's same for both tickets. The tickets are taken to separate rooms. The people in each room then pick a spot and scratch it. How likely is it that at least one of them will win?

The odds of one scratch winning are of course 50%, and the odds of the other person winning are of course also 50%. The odds of both people winning are 25%, and both people losing also 25%.

The CHSH experiment suggests otherwise: that when one person loses the other person is less likely to also lose, such that the likelihood of both losing is only 15%. How can this happen? I haven't a clue. I'm not a theoretical physicist, and I haven't personally conducted this (~ $5,000) experiment. But it's a result that deeply bothers me.

If you build this system you can then scratch a whole lot of tickets. Each ticket has a 50% chance of a side having the prize, but as long as both parties are consistently scratching the same side of entangled pairs they will win more often than they lose, revealing whether or not they are in agreement. I have no idea how this could be true, but people keep running the experiment and keep getting similar results. And, it seems like this could result in faster than light communication, so there's probably a better ELI-5 out there.

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

#93

Post by rbanffy »

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…

> we are presently incapable of detecting ourselves at a distance of 4 LY

You don't need to detect a civilisation. All you need to detect is a planet hospitable to whatever biology suits you.

That said, our detection tech improves relatively quickly and we might be able to directly image rocky planets before this century is over. It's safe to assume that, if there is someone curious enough to look for planets with biosignatures or technosignatures that has been perfecting their craft for thousands, or millions of years, by now they must be very good at that.

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

#94

Post by BriggyDwiggs42 »

tombert wrote: post #82
staunton wrote: post #80

Earlier quoted context omitted.

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…

Fundamentally there don’t seem to be any physical laws prohibiting us from solving biological immortality at least, so maybe if we can get the robot bodies up and running for ourselves we’d be able to do some exploring over a very long time.

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

#95

Post by trimethylpurine »

bilsbie wrote: post #87
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?

It's a trick question. Gloves go in a glove box.

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

#96

Post by notfed »

bilsbie wrote: post #87
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?

Yeah really, they didn't give any example of the "more"...

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

#97

Post by Jensson »

bilsbie wrote: post #87
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?

The gloves doesn't change their state when you check on them. Quantum particles do.

Example: Lets say you check if the glove is white or black, you see it is white. Then you check if the glove is half white/half black, or half black/half white, you see it is half white/half black. Then you check again if it is white or black, now it is black. That is how quantum gloves would work, but real gloves doesn't work that way.

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

#98

Post by rbanffy »

TheDudeMan wrote: post #2

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

Yeah right... Epstein drive and wormholes, with some nasty ghosts unhappy about aliens using intelligent nano machines for building extra-dimensional highways through their neighbourhoods.

It's fun, but it's not an accurate prediction of our technological abilities.

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

#99

Post by moate »

spintin wrote: post #84
spintin wrote: post #15

Earlier quoted context omitted.

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...

Lol classic smug comment about HN comment culture acting as if you're owed discourse.

FWIW, I'm also pretty sure this type of comment (and therefor my comment?) are against the rules, but I've been rate limited for like 90% of my time here because I don't use burners to get into fights so dafuq do I care.

Anyway, hope you have a Good Friday. If it makes you feel better, you're much lower on the crucifixion scale than the even providing it's name.

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

#100

Post by xandrius »

BriggyDwiggs42 wrote: post #94
tombert wrote: post #82

Earlier quoted context omitted.

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…

Fundamentally there don’t seem to be any physical laws prohibiting us from solving biological immortality at least, so maybe if we can get the robot bodies up and running for ourselves we’d be able to do some exploring over a very long time.

No exploring for me though :(
Post reply on HN