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Testing Quantum Behavior — From Earth to the ISS

timothy posted more than 5 years ago | from the houston-will-you-have-heard-me dept.

Encryption 196

KentuckyFC writes "Einstein famously believed that the instantaeous effect of quantum entanglement would allow 'spooky action-at-a-distance' in violation of special relativity. Every test of entanglement on Earth has so far agreed with quantum mechanics but naysayers continue to point out various loopholes that might allow the results of these experiments to be determined in advance rather than instantaneously as QM suggests. Today, an international team of scientists is proposing the mother of all entanglement experiments, to be performed in space. The plan is to send entangled photons between an observer on the ground and one on the International Space Station. By the peculiarities of special relativity, the high relative velocity between the observers means that both will always be able to claim to have carried out their measurement first, thereby ruling out the naysayers' arguments (abstract). The experiment, called Space-QUEST, would be housed aboard Europe's Columbus module and would give the much-derided ISS a stab at doing some decent science for a change."

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196 comments

Post (5, Funny)

Stooshie (993666) | more than 5 years ago | (#23724761)

I posted this next week and it's still the first post.

Re:Post (5, Funny)

rugatero (1292060) | more than 5 years ago | (#23724825)

No fair! You changed the outcome by measuring it!

Re:Post (1)

Stooshie (993666) | more than 5 years ago | (#23724913)

There's nothing to measure (until next week at least).

Re:Post (0)

Anonymous Coward | more than 5 years ago | (#23725875)

It's a quote from Futurama. Professor Farnsworth is at the horse track and his horse looses at the photo finish.

Re:Post (1)

aikodude (734998) | more than 5 years ago | (#23726401)

It's a quote from Futurama. Professor Farnsworth is at the horse track and his horse looses at the photo finish.
actually it was a quantum finish. there'd be no problem with a photo finish.

Science coverage on /. is crappy (5, Informative)

YA_Python_dev (885173) | more than 5 years ago | (#23725375)

Coverage of science news on slashdot is very often crappy, but we see the worst when it comes to space news.

would give the much-derided ISS a stab at doing some decent science for a change.
"For a change"?!?! Where the hell are you getting your informations about the science done on the ISS? On Fox News? There is *a lot* of science done on the ISS: literally hundreds of small, medium and big experiments have already been completed and the rate is increasing now with the European and Japanese labs on board and will increase even more starting next year with crews of six people.

Sure it would be nice to do even more, and sure the costs are high (in part due to the STS, a nice but incredibly inefficient LV), but all this group-thinking about the "white elephant" ISS is akin to saying that kernel programming is easy. It's stupid, flat wrong and insulting for the people that get a lot of good work and science done.

On Liberal Slashdot, we hate the ISS (-1, Flamebait)

Anonymous Coward | more than 5 years ago | (#23725869)

Didn't you get the memo? America doesn't deserve access to space because we're a nation of cretins who invade other countries illegally for the purpose of stealing their oil and murdering their babies. NASA needs to be stopped, and we need to destroy their blueprints to ensure our dependency on European space programs (and make it easier for historical editors to prove that we never really went to space anyway, it was only lies.) Only when we have sufficiently rehabilitated ourselves in the eyes of the civilized world (consisting of Iran, China, and the European Union) should we be trusted with anything more advanced than a flashlight.

Re:On Conservative Slashdot, we hate the ISS (0)

Anonymous Coward | more than 5 years ago | (#23726079)

Didn't you get the memo? America doesn't deserve access to space because space isn't in the Constitution or the Bible. NASA needs to be stopped, and we need to destroy their blueprints to ensure that we never spend any more of our tax dollars on this unholy science crap. Only when we have sufficiently rehabilitated ourselves in the eyes of the Religious Right (consisting of Hagee, Robertson, and Phelps) should we be trusted with anything more advanced than a flashlight.

Re:On Conservative Slashdot, we hate the ISS (0)

Anonymous Coward | more than 5 years ago | (#23726317)

You forgot the best reason for not going to space: how do you make money off it?

Re:Science coverage on /. is crappy (0)

Anonymous Coward | more than 5 years ago | (#23725927)

Any special reason why you feel the need to deride Fox News? Because they do not portray cases as you would like to have them portrayed?

Re:Science coverage on /. is crappy (0, Insightful)

Anonymous Coward | more than 5 years ago | (#23726525)

Because Fox News is a deliberately biased organization that trumpets its "fair and balanced" nature - and that is only the first inaccuracy you see in every broadcast? Nobody to the left of Tony Snow has any respect for Fox News as a journalistic enterprise (hell, Tony Snow - one of their so-called "fair and balanced" broadcasters - was hired by the White House to be their spokesman - because he was so good at communicating the Republican message! If the Clinton White House had hired Ted Koppel, the right would be all over it). Fox Sports, maybe; Fox News, no.

Re:Science coverage on /. is crappy (5, Informative)

Artifakt (700173) | more than 5 years ago | (#23727545)

Of course this will get moderated off topic (and should) but I can't resist.
1, Fox News actually went to court and won an advance judgment that said, even if it could be shown that the newscasters had deliberately lied about a concealed source being reasonably unbiased, and it was proved that the source actually worked for a political party and was paid to make the claims that it made, Fox would still be protected by the normal laws about concealing the identity of sources and this situation wouldn't constitute possible malice with respect to libel laws. Name another news agency that has even sought such a protection.
2. In 2002, there was a study of the media where the only thing that was examined was accuracy of attribution. That is, if a news source quoted a person and said that person was a lawyer in the state of New Jersey, the study checked to see if the person was really liscenced before the New Jersey Bar at the time. If they said a source was a Vice President at a fortune 500 company, the study checked to see two things - was that company really in the 500, and was the guy's title really VP and not Assistant VP or similar. NPR and BBC both scored in the 3.8 to 4 out of a possible 5 range. PRI, MSNBC and ABC ran somewhere near the middle. Where did Fox score? 2.2 - right next to Al-Jazera!

Re:Science coverage on /. is crappy (2)

robert899 (769631) | more than 5 years ago | (#23726433)

would give the much-derided ISS a stab at doing some decent science for a change.
"For a change"?!?! Where the hell are you getting your informations about the science done on the ISS? On Fox News?
Where the hell are you getting your information about science reporting on Fox News? The Daily Kos?

Fox reports science news just as well as other MSM outlets.

Re:Science coverage on /. is crappy (0)

Anonymous Coward | more than 5 years ago | (#23726799)

>Where the hell are you getting your information about science reporting on Fox News? The Daily Kos?
>Fox reports science news just as well as other MSM outlets.

There's something about Fox News. I don't watch Fox News on TV, nor do I read it online, but sometimes if I post an opinion slightly to the right of Stalin, all of a sudden I'm accused of drinking the Fox Kool-aid.

Captcha: fascism

Re:Science coverage on /. is crappy (4, Insightful)

Actually, I do RTFA (1058596) | more than 5 years ago | (#23727605)

Fox reports science news just as well as other TV outlets.

Forgive my modification to your quote, but I think that print offers better coverage of science issues. And while Fox News may report science news as well as CNN does, an astrologer reports as much science as either one of them as well. Fox News is crap. If other TV channels are also crap, well, good job my friend, you're still watching crap.

Re:Science coverage on /. is crappy (5, Informative)

cybrpnk2 (579066) | more than 5 years ago | (#23726689)

Oh, dude, you've gotten me started. I worked on Space Station in the early 1990s and still haven't recovered from the bad taste that experience has left in my mouth. Political boondoggle white elephant doesn't even begin to cover what a stupid mess the ISS is. The only thing worse than setting it up in its shuttle-payload-upmass-hostile 57 degree inclined orbit to allow Russian participation is totally cutting off Shuttle participation in 2010. ISS was DESIGNED for Shuttle resupply during its lifetime and that resupply was first strangled and then totally cut off. Soyuz and Orion taking astronauts to this thing is a joke, and doing resupply by Jules Verne is a criminal waste. The dirty little secret about ISS is that at full mass and max solar array deployment upon completion, this thing is going to deorbit even faster from atmospheric drag than it is now and no way can Progress or Jules Verne is keep the completed assembly reboosted - only the Shuttle could. Do your homework about how far that thing fell during the years following Columbia when no shuttle visited [spaceref.com] , and that's without the full solar arrays. Once the Shuttle stops going, ISS is heading straight for the Pacific even if it takes a few years to deorbit and get there. And secretly if not in public, NASA will breathe a sigh of relief when it splashes. But I digress. Nobody even knows anymore how much ISS costs anymore because of crooked accounting hiding the drawing of funds from everywhere within NASA, but nobody argues it's at least $100 billion dollars. I cannot prove an absence of good science. Instead, YOU tell ME what the top three discoveries on ISS have been. Hell, just tell me one thing we have learned on ISS that we didn't already know. "Bones decalcify in zero G"? This was new info worth $100 billion?

Re:Science coverage on /. is crappy (5, Informative)

YA_Python_dev (885173) | more than 5 years ago | (#23727569)

I agree with a few of your points, but:

The dirty little secret about ISS is that at full mass and max solar array deployment upon completion, this thing is going to deorbit even faster from atmospheric drag than it is now and no way can Progress or Jules Verne is keep the completed assembly reboosted - only the Shuttle could.
WTF? An ATV can give to the ISS a bigger dV than the Shuttle, especially if you consider all the propellant for the boosters on the Zvezda module that an ATV can bring and the STS doesn't. But I agree that the downmass capability of the Shuttle (or something equivalent) would be useful even after 2010.

Nobody even knows anymore how much ISS costs anymore because of crooked accounting hiding the drawing of funds from everywhere within NASA, but nobody argues it's at least $100 billion dollars.
This is an often-cited figure, because it's a nice round number, but it's for the whole project from 1990 to 2017 and including all the activities on Earth. IMHO it's money well-spent for 27 of engineering and science (yes, I know, we are just getting started with science, give them the opportunity to demonstrated its value after the station is completed).

Re:Science coverage on /. is crappy (1)

Falkkin (97268) | more than 5 years ago | (#23727397)

If you want good coverage of space/astronomy news, I recommend the Bad Astronomy Blog:

http://www.badastronomy.com/bablog/ [badastronomy.com]

Speaking of which, Phil Plait (the "Bad Astronomer") is also no fan of the ISS. From his article on this same experiment:

"So some European scientists came up with the idea of using the International Space Station (I know! Using ISS for science! Wow!) to test this out."

Slashdotted already? (4, Funny)

Thornburg (264444) | more than 5 years ago | (#23724819)

Apparently the entangled photon link they were using to host the webpage couldn't hold up under the strain of Slashdot.

Re:Slashdotted already? (4, Funny)

andrewd18 (989408) | more than 5 years ago | (#23724859)

It was working fine until you tried to observe it.

Re:Slashdotted already? (1)

xalorous (883991) | more than 5 years ago | (#23724923)

Leave that cat out of this? Oh, that's right. The Schrödinger's Cat thought experiment is related to the same hypothesis.

Re:Slashdotted already? (1)

morgan_greywolf (835522) | more than 5 years ago | (#23725065)

No. It was and was not working until he tried to observe it. The probability cloud collapsed on one possibility: the cat^H^H^Hsite is dead.

Re:Slashdotted already? (0)

Anonymous Coward | more than 5 years ago | (#23725695)

"Mr SchrÃdinger, a box arrived in the mail for you today, and I opened it. By the way, why would somebody send you dead cat?"

sounds more like a metaphysical question (1)

xalorous (883991) | more than 5 years ago | (#23724857)

Kind of like the chicken and the egg.

Re:sounds more like a metaphysical question (1, Insightful)

Anonymous Coward | more than 5 years ago | (#23725333)

This question is not metaphysical.

First was egg.
It was produced by chicken's ancestor.

Re:sounds more like a metaphysical question (2, Funny)

morgan_greywolf (835522) | more than 5 years ago | (#23725651)

First was egg.
It was produced by chicken's ancestor.
Nope. First was chicken. It was intelligently designed 6000 years ago to lay eggs.

Re:sounds more like a metaphysical question (1)

gnick (1211984) | more than 5 years ago | (#23726619)

First was egg.
It was produced by chicken's ancestor.
Actually, "Which came first, the chicken or the egg?" is a trick question. The rooster's ancestor came first, thus enabling the chicken's ancestor to produce the first chicken egg. Otherwise, the egg would have been barren and appropriate for frying and application to toast.

Of course, other eggs had been around for a while...

How do you entangle a photon in the first place? (1)

andyh3930 (605873) | more than 5 years ago | (#23724989)

Just that...

Re:How do you entangle a photon in the first place (4, Funny)

Daimanta (1140543) | more than 5 years ago | (#23725063)

Scientist used Entangle!

It's super effective!

Photon capture device go!

You entangled a photon!

It was added to your photondex.

Re:How do you entangle a photon in the first place (1)

alexander_1975 (872531) | more than 5 years ago | (#23725083)

You entangle 2 photons, f.e. by creating them at the same time from the same decay-process.

Re:How do you entangle a photon in the first place (1)

camperdave (969942) | more than 5 years ago | (#23725765)

You entangle 2 photons, f.e. by creating them at the same time from the same decay-process.

Ah! It comes from the subtle glow of rotting meat, then.

Could it be useful? (0)

Anonymous Coward | more than 5 years ago | (#23725019)

Just wondering if you could put one of the quantum photons in an optical switch, and perhaps use the the reading of the other photon to flip a bit. That might actually be useful. If this were viable, NASA could have something better than radio for their next generation of probes.

Now if they're only watching the thing bounce around randomly on its own, and it happens to be in synch with its paired photon - I'm not sure how useful that could be.

Re:Could it be useful? (1)

imstanny (722685) | more than 5 years ago | (#23725107)

Just wondering if you could put one of the quantum photons in an optical switch, and perhaps use the the reading of the other photon to flip a bit. That might actually be useful. If this were viable, NASA could have something better than radio for their next generation of probes. Now if they're only watching the thing bounce around randomly on its own, and it happens to be in synch with its paired photon - I'm not sure how useful that could be.
Now, can someone untangle the that for me?

Re:Could it be useful? (2, Insightful)

SBacks (1286786) | more than 5 years ago | (#23725737)

He's suggesting using entanglement to communicate faster than light. I think he's forgetting that once your manipulate the photon, it will no longer be in sync with its pair.

Re:Could it be useful? (1)

Stooshie (993666) | more than 5 years ago | (#23725979)

But I think the second part suggests that if you let your photon bounce around randomly, you may be able to know when it's in sync with it's pair thus knowing the phase of the paired photon.

At the other end, once the fixed photon is in phase it moves to the next "bit" in the message and waits for the pair to be in phase again before "transmitting" the next "bit".

Presumably this all takes place in something approaching nanoseconds.

Re:Could it be useful? (1)

SBacks (1286786) | more than 5 years ago | (#23726071)

But I think the second part suggests that if you let your photon bounce around randomly, you may be able to know when it's in sync with it's pair thus knowing the phase of the paired photon.
But, you can't know when its in sync unless you measure it. And, once you do that, it will no longer be in sync.

Re:Could it be useful? (1)

YA_Python_dev (885173) | more than 5 years ago | (#23725617)

Now if they're only watching the thing bounce around randomly on its own, and it happens to be in synch with its paired photon - I'm not sure how useful that could be.
Not very useful for what you have in mind: even with funny quantum mechanics tricks you still can't transmit information faster than light.

Re:Could it be useful? (5, Informative)

locofungus (179280) | more than 5 years ago | (#23725625)

I'm not sure what you are trying to suggest, but you can't use entangled photons to communicate faster than light.

I've not RTFA - it's down - but basically the EPR effect allows someone to create two photons and then measure if their polarization is H or V. The result is completely random BUT, both photons will always give the same result.

Now Alice measures her photon first and lets say we get H, then Bob's photon must instantaneously turn into H (previously it was a mixture of H and V - the dead and alive cat) so that when he measures his photon he also gets H.

What's already been done is to ensure that Alice and Bob decide what measurement to do, and make the measurement, so close to the same time that it's impossible for there to be any way for Bob's equipment or photon to "know" what Alice is going to do (or vice-versa) except at superluminal velocities.

But because Alice and Bob are in the same inertial frame there's still, at least in theory, a concept of who did the measurement first and who did it second. (Alice and Bob can have synchronized clocks and record the time they did the experiment. Then they can, using normal communication, tell each other what time they did the experiment and they'll both agree who was first and who was second.)

What this experiment will do is mean that Alice and Bob won't agree about who was first and who was second. Alice and Bob's clocks cannot remain synchronized, so that according to Alice, and people sitting next to her, she did the measurement first, but according to Bob, and people sitting next to him, he did the experiment first. And BOTH will be correct because the two measurements are space like rather than time like.

Tim.

Re:Could it be useful? (3, Interesting)

locofungus (179280) | more than 5 years ago | (#23725755)

What's already been done is to ensure that Alice and Bob decide what measurement to do, and make the measurement, so close to the same time that it's impossible for there to be any way for Bob's equipment or photon to "know" what Alice is going to do (or vice-versa) except at superluminal velocities.

Just to clarify this paragraph because I've realized it's confusing.

Alice and Bob both randomly decide to measure the H/V polarization or the +/- (45 degree) polarization.

Then they get together and compare results. Where one has measured H/V and the other +/- then they throw the results away because they don't tell them anything useful, but where they've made the same measurement they find they always get the same (or opposite) results.

It's when they make the measurement that neither they, nor their equipment or photon can "know" what the other is doing.

There's also something called Bell's inequality that basically proves that the results of all of Alice and Bob's possible cannot be "known" by the photon ahead of time. (no local hidden variables).

Tim.

Re:Could it be useful? (3, Interesting)

SBacks (1286786) | more than 5 years ago | (#23725907)

I've never quite understood why this conflicts with GR. It seems like from Alice's perspective, when they both make their measurements, Bob is the superposition of having the same result or the opposite result. It is only after they communicate (restricted by the speed of light) that his results can be compared with hers and his superposition collapses. In other words, there are two measurements done by Alice, one of her photon, one of Bob, and they don't require any faster-than-light communication.

Am I missing something here?

Re:Could it be useful? (2, Informative)

BlueParrot (965239) | more than 5 years ago | (#23726467)

I've never quite understood why this conflicts with GR

It doesn't (there are other points where GR and QM conflict, but entanglement is not one of them ). Einstein thought it did because he assumed that any such interaction would be deterministic and could hence be used for communication (THAT would break GR ). Essentially Einstein never liked the idea that the universe was based on randomness, hence the famous "god does not throw dice with the universe" quote. As a consequence he repeatedly tried to disprove quantum mechanics by inventing scenarios in which the random nature of QM would conflict with GR. The surprising, and somewhat ironic, outcome of his attempts was however new insights into quantum mechanical interactions that just seem to confirm the random nature of QM.

Also, to be pedantic about it, entanglement doesn't in principle imply that an interaction is quicker than the speed of light. You could alternatively claim that the interaction occurs with the speed of light, but the ENTIRE UNIVERSE ends up in an indeterminate state similar to that of Schrödinger's cat until you receive Alice's message. Thus you can keep interactions restricted to the speed of light ( locality ) but in order to do so you would have to throw out the notion that Alice exist when you do not hear from her ( realism ).

In practice throwing away realism would force you into a rather solipsist interpretation of reality which I think even Kant would have issues trying to accept, and thus most of the time we just stick with the much more comfortable notion of having a reality with instantaneous long distance interactions. If nothing else this is a lot easier to visualize than imagining the entire world entering a superposition of states until you receive Alice's message. From a purely physical point of view the two cases are indistinguishable however, so it doesn't really matter either way.

Re:Could it be useful? (4, Interesting)

TexVex (669445) | more than 5 years ago | (#23726927)

Classical physics tells us that if you know the angle of polarization of a photon, then its chance of passing through a polarizer is the square of the cosine of the difference in angles between the photon and the polarizer. If you have a 45 degree photon, it will always pass a 45 degree polarizer, have a 50% chance of passing a 90 degree polarizer, and will never pass a 135 degree polarizer.

QM tells us that when you have two entangled photons and measure both of their polarizations, the chance the results will correlate is the square of the cosine of the difference in angles between the two polarizers . If you measure them at the same angle, the results always correlate. If you measure them at 45 degrees apart, the measurements correlate 50% of the time. If you measure them 90 degrees apart, the measurements never correlate (the results are always opposite). No matter how you look at it, this means either the results are predetermined at the time the photons are created based on the angles the polarizers will be at the time the measurements are taken, or that one measurement somehow influences the other later so the past isn't immutable.

Either way you look at it, it means the universe doesn't work the way we expect it to. If you're a glass-half-full person you want to believe in FTL and time travel, and if you're a glass-half-empty person then you think maybe the universe is deterministic.

That's why this stuff gets everyone who understands its implications all in a tizzy.

Re:Could it be useful? (1)

michelcolman (1208008) | more than 5 years ago | (#23726803)

Isn't there a way to tell whether a photon qubit is still coherent or not? That might allow communication. For example, in an experiment where single photons (one at a time) were sent out that could go through either one of two openings, an interference pattern emerged suggesting that the photons actually went through both openings simultaneously (in different parallel universes, possibly). If a detector was added to figure out which opening the photons had taken, the interference pattern disappeared. If you can invent some kind of similar or different experiment that will give a different result for polarized and mixed state photons (for example, if I'm not making some fundamental mistake, the same setup with two openings but each opening equipped with a polarization filter), the ISS can act as the detector. Use a trickle of entangled photons while the ISS is or is not measuring the photons, and check whether an interference pattern comes out. If yes, they just transmitted (or are about to transmit?) a one. Otherwise, it's a zero. Although on second thought, this entire setup will probably count as a measurement for the quantum gods, they can't possibly be that easily fooled :-) By the way, I don't know anything about quantum mechanics other than what I picked up here and there...

Thanks, that's much clearer (1)

p3d0 (42270) | more than 5 years ago | (#23727701)

Where one has measured H/V and the other +/- then they throw the results away because they don't tell them anything useful, but where they've made the same measurement they find they always get the same (or opposite) results.
Even without any knowledge of quantum mechanics, I could have told them they'd always get the same or opposite results.

Re:Could it be useful? (1)

camperdave (969942) | more than 5 years ago | (#23726389)

Now Alice measures her photon first and lets say we get H, then Bob's photon must instantaneously turn into H (previously it was a mixture of H and V - the dead and alive cat) so that when he measures his photon he also gets H.

What's already been done is to ensure that Alice and Bob decide what measurement to do, and make the measurement, so close to the same time that it's impossible for there to be any way for Bob's equipment or photon to "know" what Alice is going to do (or vice-versa) except at superluminal velocities.


Schrodinger's cat was either alive all along, or dead all along. The only thing that changes is the knowledge of the observer, not the state of the observed. Similarly with the entangled photons. They are both going to be H polarized, or V polarized the entire time. It's just that the observers will not know which until they make the observation. It's not like Alice's photon somehow transmits an "I've been observed as H polarized" message to Bob's photon. These "both alive and dead" and "mixture of H and V" statements are euphemisms for "Unknown".

That is, unless I'm missing something fundamental.

Re:Could it be useful? (0)

Anonymous Coward | more than 5 years ago | (#23726661)

you are.
bell's inequality.
look it up.

Re:Could it be useful? (1)

alexander_1975 (872531) | more than 5 years ago | (#23726665)

It's not like Alice's photon somehow transmits an "I've been observed as H polarized" message to Bob's photon. These "both alive and dead" and "mixture of H and V" statements are euphemisms for "Unknown". That is, unless I'm missing something fundamental.
Apparently, because that is in a way what is going on:

The both 'alive and dead' IS NOT an euphemism for unkown... A single system can be in a superposition of two states. In this case we are talking about a single system consisting of two photons. Measuring the state in a certain base on one side WILL collapse the wavefuntion of the entangled pare. See for example also the 'wheelers delayed choise experiment': http://en.wikipedia.org/wiki/Wheeler's_delayed_choice_experiment [wikipedia.org]
However, even if the system is 'pushed' into one of the eigenstates of the measurement machine, it can still not be used to transmit information faster then light.

Re:Could it be useful? (4, Insightful)

brunascle (994197) | more than 5 years ago | (#23727043)

they actually are both H and V polarized at the same time. you can think of them as just being "unknown" for the sake understanding why you cant use it to communicate faster than light, but it isnt what's actually going on.

we know this because in a quantum superposition, different possibilities in the superposition can interfere with other possibilities, making certain results more or less likely. this is shown by the double-slit experiment [wikipedia.org] . shooting photons at a screen through two slits produced not two stripes like you'd expect, but several stripes. this is because each photon went through 2 waves of possibilities, one through each slit, and the waves then collided with each other, making certain ares of the screen more likely to be hit than others.

Re:Could it be useful? (1)

naasking (94116) | more than 5 years ago | (#23727147)

That is, unless I'm missing something fundamental.

Your description of entanglement is known as a "hidden variable theory" of QM, and exactly what this experiment is trying to refute once and for all. QM really imply that the cat is both alive and dead.

Re:Could it be useful? (1, Informative)

wurp (51446) | more than 5 years ago | (#23727151)

You have missed something fundamental.

Here is the issue:
If you assume, as you do, that the photon has some predetermined phase A (for angle), then the likelihood of it passing through a filter at another angle B is cos(A-B) * cos(A-B). Experiments testing this by passing photons through a filter at angle A (all photons that make it through have phase A) and measuring how many make it through a filter at angle B confirm it.

BUT, if the photon had an initial angle A, and Alice and Bob both have filters at the same angle B, EVERY TIME the photon with either pass through BOTH Alice and Bob's filter, or NEITHER Alice nor Bob's filter. That can't be explained by your classical model. It can only be explained by "spooky action at a distance".

(It can also be explained by assuming that the universe splits into two cases, one where the photon passes through both filters, and one where it passes through neither, and some mechanism that prevents communication between the universes. This is the many-worlds or relative-state formulation of quantum mechanics, discovered by Hugh Everett in 1957 but unpopular until many years later.)

IHA14YOBSIPBIANAP.

(I have a 14 year old BS in Physics, but I am not a physicist).

Re:Could it be useful? (4, Informative)

locofungus (179280) | more than 5 years ago | (#23727347)

That is, unless I'm missing something fundamental.

Yes, you're missing something fundamental.

Going back to one photon.

We'll have four polarization states H, V (the normal horizontal and vertical polarization) and +, - the 45 degree polarizations.

Now Alice produces a stream of H photons and sends them to Bob. Now if Bob measures to see if they're H/V then he will always get H.

But if Bob measures if they're +/- he'll get 50/50 + and -, with each individual photon being + or - at random.

After measuring +/-, if Bob then remeasures H/V he'll again get 50/50 H and V. The measuring of +/- destroys the knowledge about H/V

If Bob measures at an angle other than 45 degrees then he'll get different proportions but he'll get sin^2 theta with one polarization and cos^2 theta with the other polarization.

Now lets consider entangled photons that will always give the same result for Alice and Bob. Initially we'll assume that Alice will always measure the horizontal polarization (0 degrees) Now lets consider that the photon "knows in advance" whether it will go through a horizontal polarizer i.e. it has (an infinite number) of hidden variables. Regardless of what measurement Bob does, an ensemble of photons can distribute values amongst these hidden variables so that Bob gets the expected correlations relative to Alice and the angle of his measurement.

But now let Alice vary her angle as well. Now the correlation depends on the difference in angle between Alice and Bob. But that angle isn't known (and hasn't even been decided) at the point the photon has been created. It could have a big "look up table" saying "If Alice angle is n and Bob angle is m then do/don't go through Alice's filter and do/don't go through Bob's filter BUT the photon that arrives at Bob's detector has to know what measurement Alice will/has done and the photon that arrives at Alice's detector has to know what measurement Bob will/has done.

But because Alice and Bob independently randomly decide what angle to measure "long" after the photon was created and their independent decisions are made so close together in time that neither can know what the other has/will do when they make their measurement due to the speed of light limit then there is no way for the photon to use its "lookup table" and get the correct statistical results.

It doesn't matter how you construct that "lookup table", unless you allow some sort of faster than light communication, using the lookup table will give different results to QM.

If you want the formal maths for that bit of hand waving then lookup Bell's inequality. He actually deduced the inequality that could be tested to prove no local hidden variable theorem was consistent with the results of QM based on measuring particle spins while most of the tests that have been done have used polarization of photons but the underlying theory is the same.

These experiments have already been done, and Bell's inequality has come down on the side of QM. Because Alice and Bob make their measurements so close together in time, not all observers will agree which one is first but (perhaps unfortunately) Alice and Bob will agree who was first and who was second. What this experiment does is close even that loophole - even Alice and Bob will be unable to agree who made the first measurement and who made the second.

Tim

Re:Could it be useful? (0)

Anonymous Coward | more than 5 years ago | (#23727411)

I'm afraid you're missing something fundamental.

You're missing something fundamental (1)

p3d0 (42270) | more than 5 years ago | (#23727743)

Schrodinger's cat was either alive all along, or dead all along.
Nope. That's classical physics. If it agreed with reality, we wouldn't need quantum mechanics.

Re:Could it be useful? (1)

amnezick (1253408) | more than 5 years ago | (#23726933)

but if i sit on the moon and have alice and bob click a remote signal when they do their measurement i will be able to tell who was first and who was second because relativity simply sucks and time is only in the human mind.

what's a measurement. (1)

oliverthered (187439) | more than 5 years ago | (#23726947)

Could you please explain what a measurement is, since clearly interaction with something isn't enough or it would be measured by the air.

Derision (3, Insightful)

OpenSourced (323149) | more than 5 years ago | (#23725099)

would give the much-derided ISS a stab at doing some decent science for a change

That won't necessarily help with the derision, as nobody denies the fact that interesting experiments are possible in space. The main point of contention will still be if you need to keep live persons there continuously to perform them. It'd have to be shown that a satellite or a simple orbiting mission couldn't have performed the same experiments for a fraction of the total costs.

Re:Derision (2, Insightful)

camperdave (969942) | more than 5 years ago | (#23725835)

It'd have to be shown that a satellite or a simple orbiting mission couldn't have performed the same experiments for a fraction of the total costs.

Well, the real question would be how many experiments do we neeed to do aboard the ISS before it becomes cheaper than sending up mission after mission after mission.

Re:Derision (4, Insightful)

YA_Python_dev (885173) | more than 5 years ago | (#23725887)

You surely can save money on the purely scientific part of the ISS by removing the human presence. If you are fine with the possibility of humanity never leaving his cradle.

But the ISS is not only about science, it's also about engineering and learning how to live for long periods off the world (the MIR was pioneer, but its design and MO would be too dangerous to use beyond Earth's orbit). The next target will be the Moon and then probably Mars, but we had to learn how to walk before we can run.

Re:Derision (3, Informative)

Colonel Korn (1258968) | more than 5 years ago | (#23725943)

would give the much-derided ISS a stab at doing some decent science for a change

That won't necessarily help with the derision, as nobody denies the fact that interesting experiments are possible in space. The main point of contention will still be if you need to keep live persons there continuously to perform them. It'd have to be shown that a satellite or a simple orbiting mission couldn't have performed the same experiments for a fraction of the total costs.
The cost of the ISS program is already ridiculously small, and the #1 thing that gets people interested in space at a young age, and in a lasting way, is the idea of people going into space.

I think it's like a zoo. Maybe the animals inside are being held in some sort of unfair captivity (I tend to think that in modern zoos most animals are pretty satisfied, but let's not go into that), but the interest and money generated by those animals creates the world's largest resource for saving their wild relatives.

Even if the ISS is never used in a way that provides more direct scientific knowledge per euro than unmanned missions, I believe it's worth it in the long term.

Spooky (5, Informative)

mburns (246458) | more than 5 years ago | (#23725227)

Remember that Niels Bohr denied that such a test of nonlocality was possible. Einstein had said that this phenomenon was "incredible" in his "EPR" article, thus rejecting his own prediction. And Bohr replied in effect that such things were taboo metaphysics.

Re:Spooky (1)

orangesquid (79734) | more than 5 years ago | (#23725497)

I am not a physicist, but it seems to me that this experiment could raise some interesting possibilities, multiple ones of which could be simultaneously true. (1) Quantization is much more complex than thought, occurs on multiple levels, relies on several decoherence phenomena, and Schroedinger's equation is a special case of something else. (2) Special relativity is quantized and has its own decoherence, and is also a special case of some larger system. (3) Quantum statistics do rely on hidden variables, and these hidden variables are so numerous as to be immeasurable and have their own special behavior involving a decoherence phenomenon that is different from previously observed forms of decoherence. (4) The notion of information, as we understand it, is a special case of something much more complicated. (5) Quantized spin is a special case of something else not before seen in experiments. (6+) Other things.

No matter what, it should yield some new ideas and possible ways to investigate ToEs, GUTs, and high-energy physics orders of magnitude larger than anything we have any idea about to date.

Still a naysayer (1)

DaveInAustin (549058) | more than 5 years ago | (#23725271)

This will be really neat, but do we need to have people on the space station to do this experiment? It's not like someone going to be observing the photons with his or her eye and agreeing or disagreeing with the an observer on the ground?

Space Quest? (1)

Dan! Dan! Dan! (826308) | more than 5 years ago | (#23725285)

I hope they remember to save their results often.

Re:Space Quest? (1)

LordKaT (619540) | more than 5 years ago | (#23725467)

I hope there's at least one incompetent janitor involved to save the universe when these photons morph into door to door insurance salesmen.

Or, at the very least, they remembered to take jockstrap from locker.

'spooky action-at-a-distance' (0)

Anonymous Coward | more than 5 years ago | (#23725301)

>> 'spooky action-at-a-distance'

Rodney Dangerfield: I got some of that 'spooky action-at-a-distance' last week. I tried to pick up this girl at a Halloween party. I said "Hey baby, your place or mine"? She told me "Both".

Robust enough? (4, Interesting)

Thelasko (1196535) | more than 5 years ago | (#23725357)

As I understand it, a quantum entangled photon is very fragile. I don't understand how or why it's fragile, but wouldn't that make this extraordinarily difficult to do? The trip to the ISS is pretty bumpy.

Re:Robust enough? (2, Interesting)

SBacks (1286786) | more than 5 years ago | (#23725701)

Its pretty bumpy for a giant spacecraft pushing itself through the atmosphere. It shouldn't be as bumpy for a single photon.

Plus, I assume they'll be using hundreds or thousands of photons over the coarse of the experiment, even if 90%+ are affected on the trip there, it will leave plenty of data points undamaged.

Re:Robust enough? (2, Funny)

Thuktun (221615) | more than 5 years ago | (#23726575)

Plus, I assume they'll be using hundreds or thousands of photons over the coarse of the experiment
An experiment involving entangled photons is hardly likely to be coarse.

Re:Robust enough? (0)

Anonymous Coward | more than 5 years ago | (#23727879)

As I understand it, a quantum entangled photon is very fragile. I don't understand how or why it's fragile, but wouldn't that make this extraordinarily difficult to do? The trip to the ISS is pretty bumpy.
Why is this marked informative? Didn't RTFA?
http://arxivblog.com/?p=317

In order to get to the bottom of this.... (1)

SGDarkKnight (253157) | more than 5 years ago | (#23725367)

they will need to enlist the help of Roger Wilco.

Re:In order to get to the bottom of this.... (0)

Anonymous Coward | more than 5 years ago | (#23725819)

Why would you need a janitor?

Re:In order to get to the bottom of this.... (1)

Stooshie (993666) | more than 5 years ago | (#23726141)

they will need to enlist the help of Roger Wilco

Actually, I'd prefer it if it was Seargant Bilco

Why not go further? (1)

moosesocks (264553) | more than 5 years ago | (#23725541)

Why not put the experiment on a probe traveling further and further away from earth?

Or perhaps on the moon.

Or mars.

This is actually a fairly exciting bit of science.

Wow (0)

Anonymous Coward | more than 5 years ago | (#23725575)

From the source (Yeah, I dont know the code, shuddup)

"There is one way to settle the matter for sure: send entangled photons to two orbiting astronauts on board different spacecraft with large relative velocities."

I just imagined a catapult, an astronaut, and a baseball glove.....

Then you need a better naysayer... (1)

pla (258480) | more than 5 years ago | (#23726135)

By the peculiarities of special relativity, the high relative velocity between the observers means that both will always be able to claim to have carried out their measurement first, thereby ruling out the naysayers' arguments

Of course, by that same logic, naysayers can always claim that each side carried out its measurement last, negating whatever benefit this "feature" supposedly proves.

Re:Then you need a better naysayer... (1)

SBacks (1286786) | more than 5 years ago | (#23726307)

Of course, by that same logic, naysayers can always claim that each
side carried out its measurement last, negating whatever
benefit this "feature" supposedly proves.
But from each reference frame, they will be carrying out their measurement first. Saying that they each are carrying out their measurement last means that the naysayers no longer are arguing on a scientific basis, but are just being assholes.

Naysayers? (1)

nine-times (778537) | more than 5 years ago | (#23726261)

By the peculiarities of special relativity, the high relative velocity between the observers means that both will always be able to claim to have carried out their measurement first, thereby ruling out the naysayers' arguments.

What naysayers? Naysayers of what? And what are their arguments?

SpaceQuest? (0)

Anonymous Coward | more than 5 years ago | (#23726451)

I guess Sierra will sue them.. they trademarked the SpaceQuest name a LONG time ago ;)

einstein (1)

Brian Gordon (987471) | more than 5 years ago | (#23726509)

He famously hated the idea of spooky action at a distance, and never accepted QM. He certainly didn't advocate it.
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