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Can Quantum Entanglement Create Faster-Than-Light Communication? (mit.edu)
Slashdot reader StartsWithABang writes: If you were to send a space probe to a distant star system, gather information about it and send it back to Earth, you'd have to wait years for the information to arrive. But if you have an entangled quantum system -- say, two photons, one with spin +1 and one with spin -1 -- you could know the spin of the distant one instantly by measuring the spin of the one in your possession.
This "incredible idea to exploit quantum weirdness" for communication was the subject of a recent Forbes article [which blocks ad-blockers] as well as a NASA mission directorate. ("Entanglement-assisted Communication System for NASA's Deep-Space Missions: Feasibility Test and Conceptual Design".) And Friday MIT News reported a research team is now making progress toward capturing paired electron halves for quantum computing on gold film. "Our first goal is to look for the Majorana fermions, unambiguously detect them, and show this is it. "
This week even 85-year-old Star Trek actor William Shatner cited quantum entanglement in a discussion of Star Trek's transporter technology, arguing that "Although a lot of the concepts in science fiction are absurd to our Newtonian minds, anything is possible because of the new language of quantum physics."
This "incredible idea to exploit quantum weirdness" for communication was the subject of a recent Forbes article [which blocks ad-blockers] as well as a NASA mission directorate. ("Entanglement-assisted Communication System for NASA's Deep-Space Missions: Feasibility Test and Conceptual Design".) And Friday MIT News reported a research team is now making progress toward capturing paired electron halves for quantum computing on gold film. "Our first goal is to look for the Majorana fermions, unambiguously detect them, and show this is it. "
This week even 85-year-old Star Trek actor William Shatner cited quantum entanglement in a discussion of Star Trek's transporter technology, arguing that "Although a lot of the concepts in science fiction are absurd to our Newtonian minds, anything is possible because of the new language of quantum physics."
TLDR: No.
Next story please.
They already have tested it, and it can't go faster than light. Apparently some people haven't gotten the message.
I used to think this was an option too, but the more I read about it, the more it became obvious that it wouldn't work. This is because, while you would easily and immediately have an influence on the paired quantumdot at Earth, even if you were 10 lightyears away, there is no way to direct or guide to any particular state in front. Meaning, the moment to interact with your entangled electron or photon, it would 'set' its state, but in a random way.
So the information encoded in entanglement is only extractable when you look at correlations between measurements on both the entangled systems. So to access that correlation information, you would need communication anyway, and that communication could not be FTL. If you only look at either system, but not the other, then you need no such communication, but you also can extract no information from the entanglement. This is actually a good thing, because much of science is done by ignoring entanglements, and the reason we get away with that is the information we are ignoring cannot interfere with our interpretation of the results of our experiment.
Suppose we split up two qubits in an entangled |00+|11state, where we've established that Alice is going to measure two overlapping bell curves with their double-slit experiment.Suppose Bob likes wavy interference patterns. The rules of quantum mechanics allow Bob to do, on his qubit, any unitary transformation like |0|112|0+12|112|012|1.
This takes our state to:
14|00+14|01+14|1014|11
Now supposing that Bob measures his qubit as 0 or 1, then Alice must measure either the wavy interference patterns 12|f0(x)+f1(x)|2 or 12|f0(x)f1(x)|2.
Bob can thereby instantaneously change, from a quantum perspective, what the outcomes of Alice's measurement are going to be.
Alice's wavefunction must change instantaneously and might even change retroactively: she may have already measured her qubit before Bob does this unitary transformation and measurement: nevertheless, to satisfy the predictions of quantum mechanics, her measurements must be consistent with Bob's manipulations. But that can't send messages. Because this thing that Bob has done is not directly visible to Alice. That's for a couple of reasons, the first being that this only generates one photon of results on the double-slit screen, which isn't enough to see the pattern! But suppose we measure lots and lots of these qubits to try and see the pattern: then the problem is that Alice doesn't know which ones Bob measured as 0 or which ones Bob measured as 1. Since there was a 50/50 chance of Bob getting either, what Alice sees is therefore:
14|f0(x)+f1(x)|2+14|f0(x)f1(x)|2=12|f0(x)|2+12|f1(x)|2.
Alice therefore still measures two overlapping bell curves, overall!
Where are the interference patterns?! That is very simple: when Bob and Alice compare their measurements in the first case, Bob's 0-measurement can be used to "filter" Alice's patterns into 12|f0(x)|2,
the bell curve of photons which passed through only the first slit, and his 1-measurement filters the results to give 12|f1(x)|2,
Bob's transformation then changes how he can filter Alice's patterns: Alice's overlapping bell curves are now made up of the ones he measured 0
for, which describe one wavy pattern, and the ones he measured 1 for, which describe the other wavy pattern, and they add up into the non-wavy pattern.
--- "To pee or not to pee, that is the question." ---
Can quantum entanglement methods be used to allow a web browser, while running an ad-blocker, to access Forbes? This might be real progress.
Slashdot reader StartsWithABang writes:
Reader? Reader? I very much doubt StartsWithABang ever reads anything here.
Can Quantum Entanglement Create Faster-Than-Light Communication?
No, it can't. This has been known for years, and gets pointed out in every quantum story on Slashdot multiple times.
If a headline asks a question, and the answer is known, I should think the last Slashdot could do is to put that well-known and proven answer in the summary.
And Friday MIT News reported a research team is now making progress toward capturing paired electron halves for quantum computing on gold film. "Our first goal is to look for the Majorana fermions, unambiguously detect them, and show this is it."
Does that have anything to do with the aim of FTL communication? Or did you just put it in because it had the word "quantum" in it?
This week even 85-year-old Star Trek actor William Shatner cited quantum entanglement in a discussion of Star Trek's transporter technology
And just when I thought it couldn't get any more tenuous...
systemd is Roko's Basilisk.
Suppose I have two marbles in my bedside drawer, one red, one blue. In the morning, I get up and put one in my pocket, leaving the other behind, but without looking at either. I then go to work, say on Alpha Centauri, 4 light years away (say in a NAFAL spaceship). At some point, I pull out the marble in my pocket, and see that it is red. I now know instantly that the marble in my drawer back on Earth, four light years away, is blue.
Can that be used for communication? No. Quantum entanglement makes the choices more complex, but it doesn't allow for FTL communications any more than the marbles in my pocket do.
Well...when fucking or being fucked, there is always some entanglement involved...
--- "To pee or not to pee, that is the question." ---
Well, I also can't prove that you aren't capable of reaching out with your thoughts, grabbing the Moon, and hurling it into the Sun.
However, the preponderance of evidence strongly suggests that you can't. In fact, it would be silly to believe that you could, even though noted physicists like William Shatner say "anything is possible". I'll even go so far as to claim that you can't, even though I admittedly don't have a lot of experience, experimental data, or resources to devote to telekinetic orbital mechanics.
Actually, what they are doing is sending entangled pairs of photons (both of them) through a classical channel (at the speed of light) and using complicated mathematical quantum tricks to make it slightly more likely for the message to arrive without errors. Apparently, using entangled photons allows a more efficient transmission (less errors) than just using ordinary pairs of photons. But the message still travels at the speed of light.
Meaning, the moment to interact with your entangled electron or photon, it would 'set' its state, but in a random way.
didn't we overcome the uncertainty principle when making quantum computers?
Anons need not reply. Questions end with a question mark.
seriously, please reject all stories with links to forbes from now on.
Anons need not reply. Questions end with a question mark.
I'm just typing this before I crawl into my Primer tube at the storage depot to take a peak if FTL works in the future.
Actually there's an interesting proof by David Wolpert that this sort of thing can't work the way you think it can. It sort of goes like like this in rough outline. There's only so much information that the state of the universe can encode. If you import information from another time frame to the current time frame you have to lose some information. He goes on to argue that information transport from the past, which is immutable, to the future must be lossy. So you can't send information outside the light cone faster with perfect fidelity. This is not the same as a lossy channel-- which can use error correction to encode perfect transport.
Some drink at the fountain of knowledge. Others just gargle.
Tachyons have never been observed. Even if they can exist, there is no known means to generate them. The only reason to believe such a particle is even possible is that they are a valid solution to certain equations in special relativity.
Before thing comes first
Violate Causality
I now have first post!
I should use this sig to advertise my book ISBN-13 : 978-1501515132.
Obviously, I am not a physicist, so I genuinely asking this.
I get that the change of the state would be random and thus there is no way to predict how the state will change. But do you need to know?
I mean lets say the ship was 10 light years away and the partner was here on earth.
Let's say that we figured out a way to both measure a change in state instantly. How it changed isnt important, only that it did change.
We also figured out a way to change the state when we want to.
Could we not just use frequency of the change like mores code?
I also seems not correct to say it cannot work because we would violate a law. As I understand it, no one has a clue how quantum works. Hell, maybe those little suckers just make a tunnel that connects right through space time to the partner. Who knows!
There's a difference between "we have no idea how to do this" (heavier than air flight 500 years ago) and "we have a lot of experimental evidence demonstrating that this works in a manner that will absolutely not allow for that" (the current knowledge about quantum mechanics and what it means for entangled pairs of particles).
We know they exist, they were the answer to a New York Times crossword puzzle. Or at least, those were the sequence of letters that fit the space and made sense.
This link will work fine even with ad blockers:
http://webcache.googleusercont...
You can also change your user agent to Googlebot to workaround such shenanigans.
Slashdot gets worse every day... Pipedot: News for nerds, without the corporate slant
The point is that it is *not* a communication technology. You can't communicate with entanglement. Period. You can use it to support something like encryption, however, but the communication needs to come from a different method.
However, if you want to have something that passes through the Earth like it isn't there, you want neutrinos. However, the problem with neutrinos is that being something that barely reacts with the entire mass of the Earth, you're not going to be able to actually detect them on your transmitter either. At least not unless there is some manner of efficiently detecting neutrinos in (relatively) small devices that we are as yet unaware of. As it stands, there are millions of neutrinos that pass through the Earth every second, and probably only like a few hundred of them actually interact with any atom in the entire mass of the planet.
Generally, those aren't his entire articles. They're summaries, with links back to Forbes. It's a holding spot so he can double dip on ad revenue.
"Freedom in the USA is not the ability to do what you want. It is the ability to stop others from doing what THEY want"
You do not understand entanglement.
That's not how entanglement works. In your example, with entangled photons being sent from halfway between A and B, all A and B can do is measure their particles and then, afterwards, find out that their measurements matched. Neither A nor B can choose which information to send.
It can be proven that both particles really were in a superposition of states until they were measured, and they did not contain any hidden variables that would determine the outcome, so the "information" of what state the particles ended up in had to travel faster than light from one to the other, but A and B have no control whatsoever over this information. All they can do is compare their measurements and find that they somehow ended up matching.
If someone ever did find out how to transmit actual, usable information faster than light in any way, that would automatically mean that it would also be possible to send information back in time. Things that are simultaneous for some observer are actually not simultaneous at all for a different observer who has a different speed (as has been proven with GPS satellites). So something that travels "instantaneously" for one observer, is actually traveling back in time from another point of view. Repeat this back and forth to send information back in time to the same location, allowing you to get tomorrow's stock quotes, or possibly hiring a hit man to kill you before you could send the message you hired him with.
Now, with parallel universes this could still work without contradictions (you might get a message from one universe but end up living in another universe where things are completely different) but it certainly is not as problem free and straightforward as you make it seem.
Trust me, people are not just saying FTL is impossible because they are narrow minded. Scientists that are much smarter than you have thought about this a lot longer and harder than you. That does not mean that they cannot possibly be wrong, but you certainly ought to educate yourself on the subject before dismissing their hard work like that. It's not as simple as you think.