Quantum Experiment Shows Effect Before Cause 465
steveb3210 writes "Physicists have demonstrated that making a decision about whether or not to entangle two photons can be made after you've already measured the states of the photons."
Here's the article's description of the experiment: 'Two independent sources (labeled I and II) produce pairs of photons such that their polarization states are entangled. One photon from I goes to Alice, while one photon from II is sent to Bob. The second photon from each source goes to Victor. Alice and Bob independently perform polarization measurements; no communication passes between them during the experiment—they set the orientation of their polarization filters without knowing what the other is doing. At some time after Alice and Bob perform their measurements, Victor makes a choice (the "delayed choice" in the name). He either allows his two photons from I and II to travel on without doing anything, or he combines them so that their polarization states are entangled. A final measurement determines the polarization state of those two photons. ... Ma et al. found to a high degree of confidence that when Victor selected entanglement, Alice and Bob found correlated photon polarizations. This didn't happen when Victor left the photons alone.'
In other quantum news . . . (Score:5, Funny)
Nevermind -- why bother telling you if you already know :-(
Re:In other quantum news . . . (Score:5, Funny)
The bartender says "no faster than light travel allowed in here."
A tachyon walks into a bar.
Re:In other quantum news . . . (Score:5, Funny)
Know any good jokes?
Re:In other quantum news . . . (Score:5, Funny)
I just experienced the effect firsthand. I was confused before I even read the summary.
Re:In other quantum news . . . (Score:5, Funny)
Gypsy: No
Interviewer: Is it true that you can read minds?
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Gypsy: No
Interviewer: Is it true that you can read minds?
Gypsy husband to wife : Stop draging up the future.
Asimov predicted this years ago... (Score:5, Informative)
http://en.wikipedia.org/wiki/Thiotimoline [wikipedia.org]
Re:Asimov predicted this years ago... (Score:4, Insightful)
Re:Asimov predicted this years ago... (Score:4, Informative)
Sigh... (Score:5, Funny)
*Looks at physics degree.*
*Tosses it in the trash.*
Re:Sigh... (Score:5, Funny)
Shouldn't that be updated to be:
*Tosses it in the trash*
*Looks at physics degree*
Re: (Score:2, Funny)
Top-posting
No, what?
Do you know what is the worst practice on usenet?
Re:Sigh... (Score:4)
Not quite. It's:
Top-posting.
No, what?
Do you know what the worst practice on Usenet is?
Paradoxical (Score:5, Funny)
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shhh! That's the halt instruction for our universe.
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Hmmm... if we were to keep Alice and Bob one light-millisecond from Victor, could we send messages back in time? Imagine we're continually repeating the process of emitting photons as in the summary.
1) An earthquake happens. Victor entangles the photons.
2) Alice and Bob detect correlated polarizations, and instruct Victor to entangle his photons.
3) This process continues, bringing us one millisecond backwards in time at each step. (Minus the time to perform the measurements and inform Victor)
4) Lab sta
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Still, creating a paradox would be cooler - i.e. telling victor to entangle the photons when they get different results or vice versa. Maybe that makes time go backwards or something like that just to avoid the paradox
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I'm not sure how serious you are, but I'll point out the problem at the risk of killing the joke. The issue is in step 2. Photons travel at the speed of light (by definition). Because we cannot send information faster than the speed of light, the photons arrive at Victor strictly before any message from Alice and Bob.
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Photons can also bend their paths, so just because they travel from Alice/Bob to Victor doesn't mean Victor is that many light-meters away. The photon could be traveling in a circle. But then, I don't know what that does to polarization :-)
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Not true: we can make photons travel much much slower than c (the speed of light in a vacuum), while transmitting the information up to c, which means we could certainly communicate information faster than the photons travel to Victor. In fact, most fiber optic cables IIRC transmit light at ~3/4 the speed of light in a vacuum.
Of course, it still almost certainly wouldn't work. I actually wouldn't be surprised if anyone setting up such a system noticed that Victor entangling the photons didn't correlate Ali
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Re:Paradoxical (Score:5, Interesting)
I'm not sure how serious you are, but I'll point out the problem at the risk of killing the joke. The issue is in step 2. Photons travel at the speed of light (by definition). Because we cannot send information faster than the speed of light, the photons arrive at Victor strictly before any message from Alice and Bob.
Just use a fiber optic cable to make them wait longer. Or bounce between mirrors in a zigzag - this way light trajectory can be long, but the spatial distance can be short.
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Just use a fiber optic cable to make them wait longer. Or bounce between mirrors in a zigzag - this way light trajectory can be long, but the spatial distance can be short.
This would cause the photon to interact and hence the waveform to collapse.
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Victor should decide not to entangle the photons whenever Alice and Bob's polarizations are correlated. That'll rip physics a new one...
That would require observing the Alice / Bob results first, thus "changing" the Victor photons before he can do anything.
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causality (Score:5, Interesting)
AIUI, the notion that information can't be transferred faster than the speed of light is based on the fact that it would violate causality. I have wondered whether causality is an assumption rather than an actual property of the universe.
If it is (I'm not qualified to interpret this experiment), we'll have a lot of new physics coming down the pike over the next few decades.
Re:causality (Score:4, Funny)
Given that now cause/effect are now uncertain...
are you sure about that? :)
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the notion that information can't be transferred faster than the speed of light is based on the fact that it would violate causality
Well, it would pose problems to the way modern physics interprets the concept of spacetime (and not without ample experimental evidence.). If you asked someone with a more newtonian view of the universe, something traveling over the speed of light isn't going back in time, and so there's no causality violation.
Anyway this experiment would seem to leave open the question as to whether the Victor measurement could be performed in time to inform Alice and Bob, unless that can be ruled out by other factors.
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I have wondered whether causality is an assumption rather than an actual property of the universe.
Causality is absolutely an assumption, one that physicists have understood that they are making -- among others -- for a long time. It might be an invalid assumption that only appears to be correct most of the time.
And what a fucking weird world would that be? Could we even reason about such a universe? It might be impossible.
I know I'm not going to let go of this assumption until there is some very, very convincing evidence.
OK... (Score:2)
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don't worry, you've already decided......
T-minus... (Score:2)
There's a simplier solution (Score:5, Funny)
Comment removed (Score:5, Funny)
Great Deal... (Score:2)
I was already confused before reading the article, that proves effect before cause.
Maybe I'm Understanding This Wrong (Score:2)
More studies have to be done to see how the correlation relates to the time interval between observation and choice, the current setup was just a few nanoseconds' delay.
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Re:Maybe I'm Understanding This Wrong (Score:4, Interesting)
Ok, let's rephrase the experiment. You have four photons - A, B, C, D. A starts off entangled with B, C starts off entangled with D.
What the experiment appears to show is that if B is then entangled with C, then A is effectively entangled with D. In other words, entanglement is transitive. What it does NOT show is a violation of causality, unless I'm seriously misunderstanding the results.
(There may be other alternative explanations, but I'm satisfied that the results can be explained without resorting to violations of causation.)
However, I am going to throw in another thought -- IF it is established that causation is indeed violated, the Many Worlds theory of quantum mechanics must be false. (The Many Worlds theory says that the universe splits at the event, and that the measurement simply tells you which universe you're in - until then, there's a given probability you're in any of the possible universes. However, the event hasn't taken place at the time of the measurement here, so all probability waves must coexist, so you should observe every possible state. This isn't what's observed. Ergo, one or both of Many Worlds and Violation of Causality must be wrong.)
The new get rich scheme! (Score:4, Funny)
2. ???
3. Collide some photons!
Re:The new get rich scheme! (Score:5, Funny)
Reality versus Obeservation (Score:5, Interesting)
I really which quantum people would stop acting like they know what they are talking about.
This is just a really shitty description/way of looking at a series of events and is more or less wrong in the same way that saying your traveling back in time by looking at old stars in the sky from far off distances.
The only thing out of order here is the observers note taking and logic. Due various other quantum flux it may appear to happen in a certain order even though it didn't and its just a matter of appearance due to propagation effects.
Its a bad observation and bad description of that observation, not a causality violation.
Re:Reality versus Obeservation (Score:5, Interesting)
That phrase is also missing some better note taking and logic. Does it have any meaning? It's not a bad observation at all, altought I'd agree that is a bad description.
To summarize the article, scientists confirm (again) that Quantum Mechanics works as designed. Despite all the naysayers (ok, there aren't many anymore), and the despair of people trying to create any deep understand over what is a purely pragmatic model, the Universe works exactly the way QM says it will. On a related notice, causation is preserved, unless you want any deep understanding of it.
Glitch.... (Score:2)
Let's violate causality! (Score:5, Informative)
Or at least try...
So a key part of the experiment was that the pair of photons sent to "Victor" went through a 104 meter cable to ensure that whatever Victor did, Alice and Bob measured their polarizations first.
Presumably, one could extend this cable to increase the amount of time between Alice and Bob's measurement and Victor's decision to entangle or not.
Presumably long enough for Alice and Bob to send the result of their measurement to Victor.
And then instead of an RNG, Victor chooses to entangle based on whatever would contradict Alice and Bob's measurement.
Come on, we have to try...
P.S. the paper says they aren't violating causality, and it only looks like they are if you're looking at it wrong.
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I would suggest that their measurements were not made before Victor's decision, but merely before Victor's realization of that decision. Victor believes that his decision was random, but in fact it was actually biased strongly (and possibly determined entirely) by the overall state of the universe as a whole.
Newtonian physics would suggest that if you could simultaneously know the position, velocity, spin, etc. of every particle in the universe, you could know the future. If one particle is entangled wit
Quantum Physics @ Home (Score:5, Interesting)
The experiment in the article is ... awesome. Though if history is any indication, hoards of raving Slashdoters will try their damnedest to force this into a classical mechanistic world-view.
So here's a fun experiment you can do at home! (Craftsmanship is important for good results.)
1) Start by setting up up a classic double-slit experiment. A laser pointer and some household junk is all you need.
* Observe the interference pattern.
2) Stop denying that you went to see "Avatar" 36 times and grab a couple pairs of 3D movie glasses.
2a) Alternately, you can just buy a polarizing filter sheet. (this is the better way)
3) Being careful to note orientation of the filter, place the filters in front of the slits with one oriented 90 degree to the other. (This is only tricky because the distance between the two slits is so small.)
* What happened to the interference pattern? You "tagged" the individual photons so that you could, in principle, know which slit they passed through, so instead of going through both, they went through just one.
4) Place a third sheet of polaroid between the slits and the detector screen, oriented half-way between the two other filters (if one sheet is vertically oriented and the other horizontally, this sheet will be oriented at 45 degrees)
* The interference pattern is back? WTF? You took the tag away, so that you couldn't know which slit a photon passed through. You "erased" the which-path information so each photon went through both slits, instead of just one of them.
Do the experiment. Accept that the physical world is weird as shit. Shut-up and calculate.
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Some men just want to watch the world learn.
Re:Quantum Physics @ Home (Score:5, Informative)
I am an OSGS (Optical Sciences Graduate Student) and you don't need Quantum Mechanics to explain the experiment above, all you need is classical wave optics.
Linear polarization is electric field in a specified direction, lets say you have the electric field oscillating in the x direction and in the y direction for the first slit and the second slit respectively. Those directions are orthogonal to one another, so cannot interfere (the inner product is zero). But, if you have some component from both slits in some direction (for your example you will be getting out sqrt[2]/2 of the x component in the 45 degree direction and sqrt[2]/2 of the y component in the 45 degree direction when you insert the 45 degree polarizer, which is basically equivalent to the no polarizer case except you have reduced the amplitude). Then you have slit interference in the classical sense as illustrated here : http://astro1.panet.utoledo.edu/~lsa/_color/14_interference.htm, you will have to scroll down to see the two slit interference. Note that we see a sinusoidal pattern because our eyes view the time averaged irradiance (intensity) of the wave pattern, the the wave pattern itself.
What is different about the quantum case is that you can send, say electrons, through the slits *indivdually*, one at a time and they somehow interfere, that is what is intuitively strange.
result of "many worlds" being true? (Score:5, Interesting)
What this article is saying, is that victor's decision to entangle his photons has a direct effect on the results that alice and bob get from their double blind measurements.
So, either there is retrograde communication on time's axis, or....
The decision that victor makes is predetermined, by the act of measurement undergone by alice and bob. (Meaning victor doesn't really have as much free will as he thinks he does.)
Proposed followup experiment:
Alice and bob examine their photons, tell each other, but not victor. Victor decides to entangle or not entangle. Examine new correlation.
This will test "does a correlation between alice and bob indicate that victor will entangle?".
If it does, you have a reasonably strong test case for many worlds.
Effect without a cause (Score:3)
Subatomic laws
Scientific pause
Synchronicity
or there is no free will (Score:3)
One explanation of the results, should they hold up is that Alice, Bob, and Victor's actions were predetermined before the photons were generated and thus had to correlate.
You could say that the actors then had no free will, or you could imagine a scenario where somehow the actions of all three were entangled via an earlier free will choice.
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Or something non-observable already contains the information about the entanglement and the acts of Victor, Alice and Bob are all determined by the non-observable information holder.
ok, but... (Score:2)
... what happened to the cat?
So lets see if I get this (Score:2)
Even better (Score:3)
I don't think this violates causality (Score:3)
The researchers are assuming the actions of Victor to select a specific polarization and entanglement are somehow independent of the entire quantum configuration space. In other words, they're assuming free will, and the existence of external magical souls that are somehow independent of reality.
If you assume determinism, Victor's actions should be consistent with the configuration space, and so when measurements are made by Bob and Alice that are correlated, it increases the probability that Victor will choose to entangle.
Causality violation makes only for good headlines (Score:3)
The wave-function is nothing but a correlation machinery that organized nature's limited resources to properly fall into place (without upsetting causality as the correlations can only be sorted in hindsight).
This demystified view of QM is still very much overshadowed by the Quantum Hippie version [wavewatching.net] that makes for better headlines. I.e. non of the pop science sites clearly report this tidbit of the authors wisdom. Causality violation draws more web traffic.
Delayed Choice Quantum Eraser (Score:3)
Sounds very similar to the delayed choice quantum eraser experiments performed by Wheeler et al. The main difference sounds like the use of polarized filters instead of the double slit diffraction.
http://en.wikipedia.org/wiki/Delayed_choice_quantum_eraser [wikipedia.org]
Re:Time delay - info from the future? (Score:5, Informative)
The summary doesn't say what the time delay is between when Alice and bob measure their polarization and when victor makes his choice.
FTFA:
Due to the 104-meter fiber-optic cable, Victor's measurements occurred at least 14 billionths of a second after those of Alice and Bob
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Re:Time delay - info from the future? (Score:4, Funny)
They want sub-millisecond latency on high-frequency transactions? We'll give them negative latency! Let's see what they do then!
Re:Time delay - info from the future? (Score:5, Funny)
Re:Time delay - info from the future? (Score:4, Funny)
Re:Time delay - info from the future? (Score:5, Funny)
So, are they working on something that makes light travel a long distance and/or go slower before making that "decision", thus achieving a substantial delay that could actually be used for "time travelling information"?
Under the simple interpretation, nothing "goes back in time." It's essentially two Schrodinger's cats (A & B) being in a superimposed state for several nano-seconds. Then V adds a constraint, and eventually the A, B, and V information bubbles interact and collapse into an observed state that the scientists record.
The meta-computer that runs our universe probably printed a log message like 'ATOMIC MERGE-OP unexpected long delay on eval: d=7m, t=23ns.' If scientists persist in this sort of research, the person running this universe will probably just ^C the app.
Re:Time delay - info from the future? (Score:4, Insightful)
As usual, QM's explanation is saying "uncertainty" very slowly and profoundly. (Slowly for the dim-witted among us, profoundly for the benefit of the Nobel selection committee).
Seriously. TFA states that the measurements are not literal, and correlation between measurements happens after the fact.
So: quantum entanglement gives you a way to defeat uncertainty, by letting you measure the mutually exclusive information from a set of correlated particles... Except no it doesn't, because you can't be certain of your measurements.
And: clever experiments like this let you send information back in time.... Except that no it doesn't, because the universe still has plausible deniability (i.e. you only thought you sent information back in time, but it turns out, the universe was going to do what it did anyway and/or your measurements of what happened are uncertain).
Congratulations, QM fags. You've found another brilliant way to show how fucking retarded you are.
Re:Time delay - info from the future? (Score:4, Insightful)
The speed of light is known with a precision that goes quite beyond that. After that, the timing is a simple question of arithmetic.
Re:Time delay - info from the future? (Score:4, Informative)
The speed of light was not the problem. The problem was the timing of the detection of the neutrino. Slight - but significant - difference.
Re:Time delay - info from the future? (Score:4, Informative)
Since the meter is defined as the distance light travels in 1/299792458 second
You forgot "in a vacuum."
Re:Time delay - info from the future? (Score:4, Funny)
That reminds me of the old joke.
One day, the teacher asked Johnny, "What's the difference between 14 billionths and 15 billionths?
Johnny answered, "That's what I say, What's the fuckin' difference?!"
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Re:Time delay - info from the future? (Score:5, Informative)
Article says! It's on the order of 14billionths of a second.
When you say it like that, it sounds small, but if I did my math right, 14billionths of a second is the same amount of time as 28 clock cycles on a 2GHz processor.
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14 billion divided by 2 billion would be 7.
Right?
28cycles = (14/1Billion) sec * 2BillionCycles/sec (the paper [arxiv.org] says 14ns-313ns which is my interpretation)
0.142858rep cycles = (1/14Billion) sec * 2BillionCycles/sec (a possible misinterpretation)
7sec^2/cycles = 14Billion sec * 1sec/2BillionCycles (a very strange interpretation given unit analysis)
So although your statement appears to be mathematically correct, I fail to see how it is applicable to my statement...
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Segmentation Fault, Core Dump:
14 billionths of a second != 14 billion per second
Damn.
Cabling? (Score:5, Funny)
FTFA:
They probably hired the cable guy that got fired from CERN [wikipedia.org] a few months ago.
Re:Cabling? (Score:5, Funny)
They actually decided to one-up the CERN-OPERA people.
They fired the cable guy before they even hired him!
Re:Time delay - info from the future? (Score:5, Informative)
First of all, quantum effects like this don't allow the passage of information (no quantum entanglement effect does, it would violate relativity). Alice and Bob don't know if their photons are entangled simply by examining them. As a rule, quantum effects are worthless for transmitting information of any kind: both parties know what the other's state is if they know the photon's were entangled, but that is insufficient to transmit any kind of information (it is very useful for encrypting information, but not transmitting it), so you cannot build a useful transistor system using this.
Secondly, the Ars article rightly points out that concluding that effect proceeded cause should be rejected without much much better evidence. I can't explain the results, but throwing out causality so rapidly would be foolish.
One thought I had was that the detectors might actually be in a quantum state (basically, entangled with the photon they observe) after making their observation, which isn't collapsed into an entangled (or not) state with the other photon until Victor makes his decision. In other words, these results might not show up if you increase the timescale, because the quantum state of the detectors after they sense the photons (which, if it lasts long enough, can be affected by Victor after they detect the photon polarization without violating causality) might collapse before he decides to entangle the photons or not. I am, of course, not a quantum physicist, so that might not be possible.
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Results like this really shouldn't surprise anyone. We have strong reasons, both theoretical and experimental, to believe that CPT invariance is an exact symmetry of the universe. To put it more simply, the laws of physics work identically forward and backward. There is no "preferred direction" of time. The fact that one direction seems to us to be "forward" reflects our local environment (we live on an entropy gradient), not any fundamental property of time. Boltzmann understood this back in the 19th
Re:Time delay - info from the future? (Score:5, Informative)
I have a pretty bad grasp/understanding of this stuff, but if two atoms are entangled, changing the state in one affects the other, right?
No. All that happens is that when the particles are entangled they will have a correlated state when measured. e.g. if one has positive spin the other will have negative. Measuring -- or changing -- the state breaks the entanglement, so you can't simply use it like an FTL telegraph.
Besides, they are working on this now, so it hardly seems futile?
They are not working on FTL communication. The "quantum communication" they are talking about is like the GP said, in a sense a new form of encryption. You can't use entanglement to communicate FTL. However you can use it to determine if your communications have been intercepted -- due to the property that measuring the entangled particles breaks the entanglement. This is awesome because it means you could transmit a shared encryption key, and detect if anyone snooped it, and either send a new one if it was, or use the shared key if it wasn't.
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This is awesome because it means you could transmit a shared encryption key, and detect if anyone snooped it, and either send a new one if it was, or use the shared key if it wasn't.
Please pardon my ignorance, but this is my train of thought:
So you send me an encryption key. I put it in my quantum container for safekeeping, board a giant rocket-ship and fly to Omicron Persei 8 [wikia.com]. 2000 years after launch I am supposed to report if there is sentient life on Omicron Persei 8. So If I meet Omicronians, I will "snoop" on your encryption key, and if not then I will not. Can you instantly "detect" it? How is this not an FTL communication?
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In order for the two parties to detect their communication was snooped at, they have to 'talk' to each other to compare measurments outcomes. that doesn not happen FTL
Re:Time delay - info from the future? (Score:5, Interesting)
No problem, I had to have it explained to me once too. They say newborns have an intuitive understanding of some basic physics, but nobody is born understanding quantum mechanics.
Frankly I don't think anyone dies understanding quantum mechanics. :)
Re:Time delay - info from the future? (Score:4, Funny)
They say newborns have an intuitive understanding of some basic physics, but nobody is born understanding quantum mechanics.
Well, in all honesty, how do you know - I mean, it not like we can ask. Maybe newborn babies do have an innate understanding of quantum mechanics, and we spend the first few years of their life to make them unlearn it? ~
Re:Time delay - info from the future? (Score:5, Informative)
Not exactly. Let me explain: when you observe a property of one of an entangled pair of objects, you automatically know the state of the other. This isn't exactly a problem, until you add Heisenbergs uncertainty principle, which states that the more you know about one property of an object, the less you can know about another (position and velocity of an electron being the classic example, but for entangled objects a better example is spin and velocity).
If observing the spin of one entangled electron lets you know the spin of both (but changes the speed only of the first, since you only observed that electron), then you logically should be able to observe the speed of the other entangled electron (which would alter it's spin... but you already know that) and know both spin and speed of both electrons precisely. This violates the uncertainty principle, so instead what happens is observing the spin of the first electron causes both electrons to change in speed, but they do so randomly: in other words, you can change one of an entangled pair by observing the other, but you cannot do so in a controlled fashion. Again, to do otherwise would be to allow one to know both spin and speed of the electron, which is impossible.
Similar logic holds true for entangled photons: observing one changes the other, but not in a controlled fashion. However, both parties can know the polarity of the other's photon (if they are entangled) just fine, which allows them to share certain secret information, which is why quantum networks are theoretically 100% secure. Anyone trying to eavesdrop will actually change the state of the photons by doing so, which can be detected. The details are, obviously, somewhat complex.
Re:Time delay - info from the future? (Score:5, Informative)
Assuming you know enough information to determine that a particle has been disentangled (and I think that this is the case), then you have faster-than-light transmission of information.
Nope. The only way you'd know that the particles had been disentangled is when the person on Mars sent you, via normal communication channels, the information they had measured and you saw that it was not correlated with what you had measured.
That's what was going on in this experiment -- Alice and Bob could not tell just by looking at their individual particles whether or not they were entangled. Even comparing their measurements doesn't tell them, since they could have gotten the same results as they would have in the case of entanglement through chance alone. Only when Victor told them which particles were entangled could they sort their data sets into entangled and non- and see that in fact the entangled set showed the expected correlation.
BTW, this is at a high level how Quantum Encryption works -- along with regular data, you send information about your entangled particle. If the information was snooped, then the entanglement is broken, and what you measure will have no correlation with the measurements you were sent. That's the only way to tell. You can't just look at the particle and say "yep, it's entangled".
This is the point - I think (Score:3)
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That's the key point. As soon as Alice or Bob lose isolation (e.g. by deciding on a stock trade,) the state collapses and there is no information from the future.
Re:Now they've done it (Score:5, Funny)
The argument goes like this:
`I refuse to prove that I exist,' says God, `for proof denies faith, and without faith I am nothing.'
`But,' says Man, `The Babel fish is a dead giveaway, isn't it? It could not have evolved by chance. It proves you exist, and so therefore, by your own arguments, you don't. QED.'
`Oh dear,' says God, `I hadn't thought of that,' and promptly disappears in a puff of logic.
`Oh, that was easy,' says Man, and for an encore goes on to prove that black is white and gets himself killed on the next zebra crossing.
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Fredrick Brown via Gutenberg: The first time machine, gentlemen," Professor Johnson proudly informed his two colleagues. "True, it is a small-scale experimental model. It will operate only on objects weighing less than three pounds, five ounces and for distances into the past and future of twelve minutes or less. But it works."
The small-scale model looked like a small scale—a postage scale—except for two dials in the part under the platform.
Professor Johnson held up a small metal cube. "Our expe
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Onion comment?
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Then: I don't think it's effect before cause because Alice and Bob's observation (not their equipments' observation) happens after Victor makes his choice.
Their "equipments' observation" is their observation. There's nothing special about sentience.
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Apparently you missed a chapter in the Interpretation of QM - one interpretation is that it requires observation by a conscious mind to cause decoherence, meaning that the measuring equipment is itself in a state of superposition up until the moment that Alice and Bob check the readouts. This interpretation has been largely relegated to cocktail conversations by scientists because it appears impossible to test, but has a certain appeal to philosophers, mystics, and New Age types.
One side effect of the int
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I wouldn't worry. After seeing the results, the researchers said they'll be extremely careful when they actually perform the experiment.
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This is part of the problem with the math we try to use to describe the universe. We don't handle zeroes and infinities very well.
For example, something goes all batshit at the speed of light. If you try to apply the math of Relativity to something traveling at c, then you get a meaningless answer that there is no time. When you try to figure out what's beyond the event horizon of a black hole (where gravi