Sounds like bollocks to me. That is to say, it appears to me that this experiment is deeply flawed.
Here is the flaw in the argument, if this "simplified" description can be taken at face value: the experimenters are NOT "influencing" the photons. They are just measuring the relevant polarizations. There is nothing influencing what those polarizations are.
Thought experiment: let's say you set up a machine to throw 2 tennis ball. It spins one to the left, and the other to the right, at random. In our experiment we assume that the machine never makes a mistake. So the spin of the balls is "entangled", in that if you measure the spin of one, the spin of the other is ALWAYS opposite.
You then set the machine to throw the balls, one ball each to two different observers. Each observer measures, when the balls arrive, what spin the ball has. (If you want to make it more analogous to the polarization experiment, you can test for certain directions of spin at random.)
Each observer will see a perfect correlation of spins! Even though neither of the balls were influenced in any way by the observer.
In order for this experiment to have any value, they would have to AFFECT the polarization of one photon (i.e., change the polarization from one direction to another), and THEN measure the result at the other observer's station. If you don't, you're simply verifying that they are entangled. You aren't actually measuring the speed of any "influence", because as far as you know there has been no influence. You can say that observation "fixes" the polarization in a particular state. But observing the polarization is NOT NECESSARILY "influencing" the quantum state of the particle. It may have already been in that state anyway; you simply don't know.
If any "influencing" of the particles other than simple observation was done here, that was gratuitously left out of the article.
Hope Strings Eternal
I'm afraid that, in quantum mechanics, measuring the polarization IS influencing the photons. The problem with your argument is that the polarization of the photons doesn't have any particular direction until they are measured. When the polarization is measured, that changes the quantum state of the photon.
I don't understand you so called scientist, they are not entangled, they bump up against each and transmit their energy that is not lost over great distance. The faster the speed the more the energy. The smaller the particle the faster it travels when it is struck by larger particles. What is so hard about this.
Anne Ominous is right! +1
re; Anne Ominous
They were randomly shifting the polarization of both particles before observing and the matched particles were still showing the same polarization.
this sounds like potential for very fast internet, in 6 months from whenever someone is wondering about when they will get to releasing it commercially... just think, stick one half of a pair of 9 photons on a pcb in one modem, the other half in another modem TADA.... instant internet connectivity, no matter what the distance between the 2 modems.
I agree with Anne,
How could you ever know that measuring something influences it? By definition it is impossible to know the value before you measured it.
There are (at least) two explanations for the results of this experiment, one is the simple common sense explanation that nearly anyone would come up with. The other postulates an unnatural non-deterministic state of matter, the direct influence of a conscious observer over matter and faster than light communication. I think Occam's razor could come in very handy here.
I'm sorry but I see no evidence here of faster than light communication.
The space between Alice and Bob moved by mechanism as result of their quantum entanglement.
The influence on space between Alice and Bob contracted speed was about 10,000 times the speed of light, but continent in space stayed mostly still.
Continent in space can not travel faster than the speed of very same energy that matter is built of in local slow clumping formation of matter, stars and galaxies. ...
There is a popular misinterpretation regarding experiments investigating the EPR paradox. This misinterpretaton is well explained for example in the paper of W. A. Hofer: "Solving the Einstein-Podolsky-Rosen puzzle: the origin of non-locality in Aspect-type experiments" (http://arxiv.org/abs/1109.6750v3).
Abstract: "So far no mechanism is known, which could connect the two measurements in an Aspect-type experiment. Here, we suggest such a mechanism, based on the phase of a photon's field during propagation. We show that two polarization measurements are correlated, even if no signal passes from one point of measurement to the other. The non-local connection of a photon pair is the result of its origin at a common source, where the two fields acquire a well defined phase difference. Therefore, it is not actually a non-local effect in any conventional sense. We expect that the model and the detailed analysis it allows will have a major impact on quantum cryptography and quantum computation."
And another important paper: A. Khrennikov, "Violation of Bell's inequality by correlations of classical random signals", Phys. Scr. 2012 014003 (http://220.127.116.11/abs/1111.1907v1)
The many worlds interpretation would explain it all beautifully ...
Search for 'The Quantum Physics Sequence' by Eliezer Yudkowsky and have a look at his section on the many worlds interpretation.
Einstein didn't ever claim that nothing goes faster than light. He said that nothing that carries information goes faster than light. Until the researcher shows that Alice can send a message to Bob by choosing how to measure her photon, the experiment means nothing.
A key flaw is contained in this quote above: "Alice's and Bob's measurements were made at the same time,..." Simultaneous? As seen by whom? Einstein showed that different observers cannot agree on whether events occur at the "same time". In this case, two other observers (Yevette & Zeb), traveling in opposite directions near Alice and Bob will report "Alice did the test long before Bob" (that's Yevette) and "No, Bob did it long before Alice!" (sez Zeb). But there's no real dispute since Alice did not send Bob any message.
Sorry Anne, I'm with Brian. In your analogy, the spin is determined at launch time. In the article that's not the case.
Gregg I love your last post.
TNS thank you, I thought I was going to be the only one who said what you did.
Please remember Einstein, Poldolsky and Rosen thought hard about this, we're probably not going to grasp it in 2 minutes of internet reading.
Einstein himself called it "spooky action at a distance".
The good professor is just tying to measure said phenomenon.
Good stuff Juan!
Synchro, where's your evidence that the spin was not determined at launch time? You have no way of knowing what the spin was before it was measured (by definition.)
If I hold a card behind my back, then show you that it's the King of Clubs, isn't it reasonable to conclude that it was the King of Clubs when it was behind my back?
Extraordinary claims require extraordinary evidence, yet in this case both the ordinary and the extraordinary explanations predict the same outcome. The evidence cannot determine between them, therefore the simpler solution seems more likely.
In the same way, it seems unlikely that there is a teapot in orbit around the sun, even though we cannot prove that there is not.
If it does happen to be correct, it might, just might, pave the way for time travel in both directions, something that I believe is limited to one way only in a non-quantum world.
It would be interesting to see what this does, if anything, for communicating from within a black hole.
What is the speed of gravity. Or is it instantaneous?
I claim not to understand any of this, which may make me the only ignorant person in this discussion. I do wonder a bit about the words "although a tiny loophole or two are still outstanding..." Loopholes in any argument are intensely interesting, and sometimes worthy of further investigation, because loopholes usually have a cause and finding what those new causes are can be a learning experience.
Speed of gravity? also think: What is the speed of magnetism...?eh?
maybe the same...what are the implications re wave or particle..?
Speaking as an engineer rather than a quantum physicist, I have to go with Anne's explanation. There is no "spooky action at a distance", the photon spins were random, but opposite, at the time they were created by Charlie as a result of some conservation mechanism. The key flaw in the experiment is that the measurements were taken with "randomly rotating" polarizers. There is no evidence of "influence" by Anne or Bob here. The description says the time of the measurement was determined by syncronized clocks. For practical purposes, there is no telling whether Alice or Bob measured first (and was, thus, the "influencer"). Sometimes I fear the physicists get too caught up in their equations and fail to look at the big picture. The common interpretation of quantum states (as I understand it) is that they may have a variety of values until they are measured, then the wave function "collapses" into a specific value and any "entangled" particles are forced to their complementary values, no matter how far they are separated. While an interesting interpretation, it does seem more likely that the states of the "entangled" particles are fixed, but unknown, at the time they are created, and the act of measurement changes nothing at the distant particle. If and when, Alice can send a message to Bob by "influencing" the state of one of a pair of entangled particles by setting her polarizer to up/down or left/right, then I will be convinced that the act of measurement actually influences the distant particle.
Brian Dodson, I'm afraid that Anne Ominous's argument is logically correct. What you claim to be a flaw in her argument, while true, is not actually a premise of her argument. To prove that information was transferred you have to have the information start at one end, and has to be known at that end before influencing the particle, and then the other side has to be able to deduce at least part of that information from a signal it then receives. "At least part" could simply mean being correct more than half the time, or in any case more often than it would otherwise be (i.e. distinct from the null hypothesis)
One possibility would be to force one of the entagled particles, after they've been separated, to have a pre-determined spin. Forcing it to take on some spin without knowing or being able to control what spin it takes does not demonstrate information transfer (aka "communication").
We still don't really understand time, distance, and matter - that much is clear. Someday...
...to add to my last comment: in brief, if Bob is sending information to Alice, then Bob must know the information before sending it, and Alice must not know the information before Bob sends it.
From what Anne described, and what you, Brian, have confirmed, this is in fact not the case in this experiment. So far from rebutting her argument, you have actually confirmed her premise.
Note: This is a necessary but not a sufficient condition. For instance, Alice could receive the information from Charlie after Bob sends it but before Alice receives it from Bob. Now if Charlie had received the information through a chain of communication originating from Bob, on or after the transmission started, it would still be valid. etc.
I think the two photons were always deterministic rather than random and all the experiment shows is that the two deterministic photons arrive at the two locations with their phases or spins correlated. I.e. the spin was never random but just appeared to be random because of how we perform the math and do the measurments. If we were blind we might say that a child swinging in a swing is random until we grab the swing to determine its position but in doing so we no longer have a random swing position. Obviously the swing was always deterministic but we just could not see its position because by being blind we had no way to measure its position at any point in time. I think you would find that if Alice were closer than Bob then Bob making the measurement would cause Alice to be deterministic after the fact. This makes no sense, therefore the entire theory this is based on must be flawed.
happyjack27, that's exactly what was done in the experiment. The entangled photon generator and the two detectors all have precision clocks, presumably atomic type.
The clocks are synchronized then whatever method was used to do that is disconnected.
The generator sends out pairs of entangled photons to the detectors.
At the entrance to each detector is a RANDOMLY ROTATING POLARIZER. They are NOT synchronized, thus as the photons enter each detector it is certain they will not have the same polarization.
Yet when their polarization is measured AFTER BEING RANDOMLY POLARIZED, their polarization is ALWAYS the same.
Do you all understand the experiment now?
I have to go with Gregg. I will use the tennis ball example.
Two entangled tennis balls sent out from Charlie towards Alice and Bob with some kind of spin. Don't care what kind of spin they start with. Not going into "how to entangle things" here.
Ball arrives at Alice - random spin is imparted.
Ball arrives at Bob - random spin is imparted.
There should be no correlation between the measured spins of the balls after random spinning.
Due to entanglement, there is a correlation between the measured spins of the balls after random action.
The timing of the events is conducted with clocks internal to A, B and C.
The clocks internal to A, B and C have some amount of error/uncertainty.
Calculation for the "speed of spooky action" was approx. 144,000x speed of light when taking the clock readings as fact.
Due to measurement system uncertainty the fastest possible "minimum" claim is 10,000x - a bit more than an order of magnitude slower.
Anne's logic is not valid in the quantum world.
One of the few things that I remember from studying quantum mechanics at University (perhaps because it was so bizarre and difficult to get my head around) was that the ACT of measurement influences (and hence changes) the phase. It is not possible to not influence the phase during the act of measurement.
Perhaps the author did not think to provide this background information if he assumed the audience were familiar with quantum mechanics.
For those getting excited about the possibilities of fast internet and faster than light signal propagation, you will be rather disappointed. This experiment does not show that any information is being transmitted faster than the speed of light.
Usually enjoy Brian's posts, but that a Ph.D in physics would write this up without pointing out that entanglement correlations can only be validated after classic information has been exchanged (as has been pointed out by many commentators) is extremely disappointing.
re; Jonathan Shock
If by manipulating the polarity of one photon you manipulate the polarity of another photon you are passing information. If you generate the pared particles and polarize them both east and then when they are arriving at the modems you flip the photon at the transmitting modem to a north or south polarity the receiving modem will be able to read the polarity as north/south or as 0/1.
Signal transmitted message received.
re: slowburn - no one is saying that by manipulating the polarity of one photon you manipulate the polarity of the other. By MEASURING the polarity of one you KNOW the polarity of the other. There is no way to change that polarity. Alice receives a random stream of bits. Bob receives the inverse stream of bits. Neither gets any information, let alone any information from the other.
Greg: The photons are not "randomly polarized" they are randomly filtered by polarization. All the results show is that the two entangled photons always have the same polarization. Hardly surprising.
re: "Anne's logic is not valid in the quantum world." The presumption that the "quantum world" somehow evades the principles of logic and mathematics is ludicrous. The quantum world as we understand it is DEFINED BY logic and mathematics! And Russel/Whitehead/Godel proved that system to be fully self-consistent! So it is IMPOSSIBLE for Anne's logic - or any logic, for that matter - to NOT be valid in the quantum world! Logic is logic is logic. You have to actually disprove it by finding the mathematical error or accept it as inevitable. You can't just wave the magic word "quantum" and expect it to disappear. And Anne's logic is inevitable, as many have reiterated here, if a, b, and c, are not satisfied, than x has not been proven. Whether it's the Quantum world, the classical world, The Matrix, or Never-never-land.
Also, felix: you took the words right out of my mouth! Nice explanation!
Necessary requirements to demonstrate FTL communication (whether it be quantum, classical, or what-have-you. really people, i shouldn't have to specify that part.):
0) firstly, it must be understood that the notion of "sending" information has a number of logical necessities, including:
0.a) the signal to be sent must be known by the sender before transmission begins
0.b) the signal to be sent must not be known by the receiver before transmission begins
0.c) the communication channel must be demonstrated to be the true shortest path.
4 points: a,b,x, and y, connected in a square: y->a->x->b->y. "a" is the sender, "x" is the channel, "b" is the receiver, "y" is the comparator.
1) demonstrate that:
y can send to a
a can send to x
x can send to b
b can send to y
a cannot send to b, nor b to a
x cannot send to y, nor y to x
* y cannot send to b
2) demonstrate that, from a signal received from b, y can deduce the signal it sent to a, with better accuracy than the null hypothesis (null hypothesis = a cannot send to x and/or x cannot sent to b),
in a time t, significantly less than the time, from y's perspective, that it takes the signal to travel from y to b to x to a to y, at the speed of light.
These requirements have not been met by the experiment in question.
This is seems to me to be an excellent brief summary of the almost unbelievable results spawned by the EPR paradox. Great job, Brian.
The reach of Einstein's thought is breathtaking. He explained Brownian motion (proving that matter is made of atoms), discovered the existence and properties of photons while explaining the photoelectric effect, created special and general relativity, predicted the phenomenon of stimulated radiation (see Laser), described the statistics of particles with different kinds of spin, and pointed to the central weirdness of quantum mechanics.
Has any other human being -- with the exception of Isaac Newton -- created as many scientific advances in one lifetime?
Every thing that is observed has a point of origin. That point, when defined as the "Nonlocality", makes entanglement easier to conceptulize. All matter, the universe, is expanding anisotropically from "a point". A point has no mass, no dimension, and time is of no consequence. Next...
The experiment would not work if you were filtering out all but specifically orientated photons. One of the matched pair would have always been stopped.
Not if the two filters were aligned when the photons passed through them. Bear in mind that the two photons passed through the filters at slightly different times.
Even if you postulate that the two photons passed through the filters at exactly the same time, which is impossible, if the orientation of the filters was random, as stated, it is a certainty that there were times at which the two filters were aligned.
To make the situation very clear, let's play through the experiment in our heads, first assuming the quantum mechanical theory to be true, and then considering a classical Newtonian explanation. We will see that both views explain the results equally:
1) A pair of entangled photons are generated at charlie, their polarization is non-deterministic. Photon 1 hits bob's filter, its polarization takes on a real value. If that real value is aligned with the filter it will pass through. At the same time the polarization of the other photon takes on the same real value. At a later time it hits its own filter. If that filter is aligned with its polarization, it will pass through. The observed result is that whenever both photons are received, they have the same polarization.
2) A pair of photons are generated at charlie with identical polarization. Photon 1 hits bob's filter. If the filter is aligned with its polarization, it will pass through. Photon 2 hits alice's filter. If the filter is aligned with its polarization, it will pass through. The observed result is that whenever both photons are received, they have the same polarization.
"at no time is there a correlation between Alice and Bob's polarization directions"
lets also assume that the researcher are competent enough to avoid the the possible but very slight timing errors resulting in matching polarity. we therefor have to conclude that the filter changed the polarity of the photons.
This could be a hint of the "hidden dimension" of singularity. Since everything began at singularity, it could be a residual effect, indicating that singularity still exists in some form. Extra dimensions are a standard component of higher physics. Dark energy and dark matter could also be hints of hidden dimensions.
Entanglement is instant "communication".
It conflicts with Einsteins relativity theory.
What if the speed of light varies through time and space?
That would create some interesting theory. At least I think so.
Quantum mechanics might not be confusing at all. If you split the entire universe into the physical universe (positive energy) and infinite separate mental parallel universes (negative energy), the wave collapse might be explainable as where all the universes meet in the quantum field. Matter and antimatter is created in this wave collapse, and that gives us the reality we observe.
You are your own universe.
Reality is where the minds (negative energy) meets and creates the physical universe. Our inner self is the observer and the the creator, and that is what we consider as consciousness.
The most interesting about it all is, that if the speed of light is infinite in vacuum, then Einstein is right again. He said that the speed of light is constant locally.
Interested? Then read my philosophical multiverse theory.
It is impossible that the two photons arrived at the filters at the same time. In the paper it states the difference in timing as over 10mm. There can be no guarantee that alignment of filter a when photon a passes it is not the same as the alignment of filter b when photon b passes it.
If what you suggest was really happening it could be demonstrated with a simpler setup: The filters should be set permanently at right angles to each other.
I won't confess to having any opinion/experience ect of the subject (though I find it fascinating) however you state that "they are NOT synchronized, thus as the photons enter each detector it is certain they will not have the same polarization" should that not be 'they are highly unlikely to to have the same polarization? I would have thought there must be some finite chance that they could be in sync
Seriously you are arguing that it is impossible to make sure that the filters can't be alined so that they can't give the same orientation to the photons for the time it take light to travel 10cm. (even though you called it milometers)
By using randomly selected orientations they are removing operator bias from the results and demonstrating that it is not a freak effect of a specific filter orientation. Somethings your fixed filters don't do.
So if their were 2 photons shot through a random polarisation to 2 recievers , when the polarisation was read by the recievers why didnt the photons revert back to the same photon?
If you believe that then I'm afraid I cannot understand your explanation for the results. You seem to be saying the following, correct where where I go wrong:
The photons are generated with indeterminate polarization
A photon strikes a polarization filter, this causes its polarization to take on a certain value. If the value is the same as the orientation of the filter it passes through.
At the same moment (or very shortly afterwards) the polarization of the other photon takes on the same value. (note that the second photon has not yet hit its own filter)
The second photon hits its own filter, which definitely doesn't have the same orientation as the first filter, therefore the second photon does not pass the filter.
Given that this explanation implies that at most one of the two photons will ever pass the filters, I cannot see how it explains the observations.
Quantum entanglement works both ways particle A effects particle B, particle B effects particle A particles A and B are always equal. If the low probability event happened that they are in fact going the filters simultaneously they must be taking a polarity equal no neither filter. I think that the filters would stop both because they will not accept the imposed orientation nor pass without it. Therefor I think that they one particle passed through the first filter and both particles accepted the imposed orientation and then the other particle passed through the second filter and both particles accepted the imposed orientation which was then observed.
Thank you. That was what I was trying to state in my own words. Without further details about this experiment, it appears that the researchers were detecting the presence of photons without necessarily "influencing" them.
For a simple example: according to the equations here:
if a photon starts out at an initial polarization of 0 degrees, it has a 0.5 probability of passing through a filter set at 45 degrees.
In that case, if you have detected its presence, it is arguable that it has been "influenced". But it seems here that the initial polarization is not known, so that is nothing more than guesswork.
AND... if the photon started out with a polarization of 0, and its presence were detected after passing through a polarization filter oriented at 0, then it is impossible to say it has been "influenced" in any way.
So while my explanation may not be a literal treatment of Hofer's or Khrennikov's work re: EPR, it is a simple gedankeneksperiment that appears to show you aren't necessarily influencing the particles you detect; you are simply confirming a correlation that you knew already existed. That was the point I was trying to make, in my amateur way.
My explanation does not depend on synchronizations being determined at launch time. Only that they be definite. Which they have to be, since the polarizations of the entangled particles are in a fixed relationship to one another.
This experiment appears to assume a great many things, which is why I stated that details are missing. And one of those assumptions appears to be that the entangled photons are NECESSARILY in an indeterminate superposition until they are detected after passing the polarization filter.
But I question this assumption on a number of grounds, among them that their method of entangling could easily force determination of the polarization and thus ruin any possibility of a superposition; however, the correlation would of course still be there. Without more details, I have no way of knowing.
Also, see the references posted by FelixS, and the following, from Wikipedia's article on photon entanglement:
"Instantaneous communication by means of quantum entanglement is actually impossible because neither side can manipulate the state of the entangled particles, they can only measure it (see No-communication theorem). This fact means that if you measure one particle you cannot infer anything meaningful about the observers measuring the other particle, except you know what state they will measure, or have already measured. Thus causality is preserved."
That paragraph seems almost custom tailored to this specific experiment. It states that the researchers are NOT "influencing" the particles by their measurements.
re; Anne Ominous
So you are saying that two randomly generated entangled photons each passed through a filter that would randomly alter its polarity into a different direction than its twin but when measured had the same polarity as its twin in no way indicates that one of the twined particles is having an effect on the other.
Given the distance and timing accuracy the influencing is happening at a velocity at least 10000x faster than light.
First let me say that I was stunned in 1997 when I first read in detail about the EPR experiments. I was also stunned when I heard Gisin speak in Montreal in 2002 and published a paper showing that the EPR correlations transmit at 10^7 times the speed of light. (Much like Yin has done)
Well all this is hokum pokum. When people try to explain this, like in this blog, they use hopeless words like spooky, magic and weird.
I worked on EPR for 16 years and now finally have a local realistic simulation of the EPR correlation that violates Bell's Inequalities.
The paper will soon be submitted and the simulation program posted. It is straightforward quantum mechanics and makes the assumption that spin actually has two axes of quantization rather than one. Then all works out.
There is a seminar posted http://bit.ly/WHj32D
and you will see other things there. All of the history described in this blog is the party line. I like most of the comments presented here.
Guys, stick by your guns and push for local realism because non-locality makes no sense, and all the data makes physical sense if spin has two axes. Think about it.
re; Bryan Sanctuary
All the data makes physical sense if you accept Faster Than Light (FTL) phenomena.
It is important to remember how science is supposed to work; one tested data point in conflict with the theory and you discard the theory.
Incidentally 's theories of relativity don't actually preclude FTL phenomena. Einstein is also quoted as saying to the effect that E=MC2 was meaningless because there was no way to convert mater to energy or energy to mater.
oops it should read.
Incidentally Einstein's theories of relativity...
Neutrino, Relativity And The Speed Of Light
With the recent experiment conducted at CERN, we are about to ensure that the speed of the neutrino is greater than that of light, which apparently contradicts radically the current theoretical framework based on the Lorentz factor, conceptualized by Einstein for Special Theory of Relativity.
But I propose a universal Lorentz factor, where the denominator of the square root is not C (speed of light), but U (variable universal), but of course, the observers A and B would perceive particles U, not electromagnetic waves or photons at speed C (with devices such as radars, cameras, the human eye, interferometers etc.), but it would have devices that capture particles U or in the case of neutrinos, neutrino detectors . And if in these conditions we make the Michelson-Morley experiment, then the neutrino velocity constant would be independent from the inertial observer's perspective it would no longer constant C for observers in mind that the speed according to the neutrino experiments at CERN travel faster than light, thus, when we calculate the Lorentz factor with C Superior speed, we are not dealing with an imaginary number, if not a positive root, since the speed of the particle would not be greater than the speed of neutrino. ( IN THIS HYPOTHETICAL EXPERIMENT INFORMATION TRAVEL WITH NEUTRINOS, NOT WITH LIGHT)
Relativistic implications of this approach are of great importance since the variation of time, mass and space dropped by Lorentz transformations would have no way limited to the speed of light but that of the neutrino in this case.
The answer I propose in this brief article is so simple that has been expressed in two paragraphs, but its implications are very important in these times when the scientific community found no answer to the new discovery of the neutrino velocity.
Since the OPERA experiment showed that was wrong. I thought of quantum entanglement, because the information in this phenomenon travels thousands of times faster than light. The theory I propose is still true.
This research is all well and good, but I've never been able to understand why no science (that I've seen) ever addresses 'spooky' with this simple gravity puzzle: If stationary massive objects A, B and C were all located (effectively isolated in space if that were possible) 1 lightyear away from each other, forming an equilateral triangle, and A moved at light speed to the center of the imaginary line between B and C, what would the plot of the 3 objects' positions over time look like? My hypothesis has always been that GRAVITY'S EFFECT OVER ANY DISTANCE IS IMMEDIATE, probably only limited to the speed of the expansion of the universe, which might be unknowable and could even be relative (there's that word again) depending upon objects' location within the universe.
As for ever seeing this applied for real world application.
there are lots of problems to be resolved yet. The entangled particles don't stay that way. They need to be brought back together to be re-entangled after being used a few times.
Lets say every problem with this is solved. Now you have a communication system that the government can't jam and can't listen in to. In what universe do you see that being made available to the general public????
Experiments like this will only benefit the military not the public.
Is that Schrödinger's cat?
It doesn't travel at all, it just IS...
So, as I see it, the problem is that there's no actual information here.
The detectors are seeing random noise; the only benefit being that they see the SAME random noise.
If there was a WAY to inject data into it, then we'd have something.
Entangle the two photons; send one through a Photon Multiplier (does anybody know if photon multipliers also duplicate spin?), and then manipulate those photons to alter the spin of the second photon with phase modulation.
pipertom what about observers that are in a different gravity field they should all get different results depending on the intensity of gravity..
What about observers that are on a different gravity field , they should get different results depending on the intensity of the gravity field they're in...
I find it strange how everyone is so sure of the answer for this, or rather so quick to dismiss it or take a kind of huh, how?? reaction, when quantum physics deals with reality on a level we are only beginning to understand.
My impression is that this is an example of the underlying fabric / another level / dimension of reality which we are unable to grasp or visualise.
Do we really think we know enough about how the universe and beyond is constructed to be able to contemplate distance as being relevant on all levels of reality?
Take a side look at reality. Think outside the box. The phenomena exists, therefore it is our view that needs to change to accommodate, we need to update our understanding of forces and planes of reality.
It's the same side look we need to take when dealing with Quantum superposition i.e. schrodinger's cat and the wave-particle duality - we're just not seeing things through eyes and brains that understand this angle of reality we're able to measure when measuring quantum phenomena.
You might say, when observation influences state, we create two parallell realities, but this can again be said to only be considering reality on a linear human time / space / dimensional way.... reality exists fine, we're just looking at something that doesn't exist in connection with the physical environment we're used to, it's behind the curtain...
Sorry to be commenting on this so long after the article was written, but it is a very interesting subject, one I have been following since I first read Bell's two articles. I read them in 1976 and they were written in 64 and 66 so this time I am a little earlier into the discussion.
Brian's description is not complete enough for thoughtful commentators such as Anne Ominous to see the issue.
You have to realize that this is entirely about probabilities. You have to do many runs of the experiment to generate the correlations. You have to do this for multiple angles and you have to calculate the correlations based on the many runs.
The experiment is set up to verify the prediction of Quantum Mechanics (QM), that the expected correlation of measurements S
S=|E(A,B) + E(A',B) + E(A,B') - E(A',B')| which classically is always less than or equal to 2, can be as higher in QM. Note that in the paper, they get this equation wrong, missing the minus sign on the last term. A and A' are two angles chosen by Alice, B and B' are two angles of polarization chosen by Bob.
The highest correlation of 2.8 is obtained when the four angles are 0, 45°, 22.5° and 67.5°. E(A,B) etc is the expectation of the correlation between Alice and Bob given the angle of polarization tested by Alice and Bob. This correlation cannot be explained using tennis balls or anything similar. There is no way to generate such a correlation if the photons already agreed on their polarization before they were measured. The same applies to revealing playing cards. No appeal to quantum logic or magic is required.
To do the experiment a set of four results is needed. One set for the angles A and B at Alice and Bob. Another set for the angles A and B'. Another for A' and B and finally for A' and B'. To calculate E(A,B) you add up all the times Alice and Bob got a simultaneous measurement (where simultaneous is carefully defined in the experiment) and you get for each one either '++', '+-', '-+' or '--' where '+' means positive polarization and '-' negative polarization (the experiment uses what are called two channel analysers, one channel for '+' and one for '-'). E(A,B) is then the sum of the '++' and '--' results (correlation) minus the sum of the '+-' and '-+' results (no correlation) divided by the total number of runs.
Now for the loopholes. As another commentator pointed out, you can generate these kinds of inequalities using classical systems where the results are of the same statistical nature. The properties being measured are themselves statistical, like temperature say. The statistical interpretation of quantum mechanics explains the correlations by saying that polarization is a statistical property of an underlying reality (the hidden variables). There is no need for many worlds, quantum logic or anything weird.
The truth is that QM has nothing to say about the result of single measurements, they can quite literally be almost anything. QM can only tell you what to expect from multiple simultaneous or repeated measurements. QM is inherently statistical. Most of the popular descriptions of QM miss this point. For instance, you often read things like this one from the Guardian:
"The uncertainty principle says that we cannot measure the position (x) and the momentum (p) of a particle with absolute precision."
This is simply untrue, the uncertainty principle has nothing to say about an individual particle and what you can or cannot measure of an individual particle. What it actually says is that the spread of expectation of momentum and position is great than a certain amount. This can only be verified by making multiple measurements. And it happens to be true of any wave theory not just QM. Effectively, you can measure the frequency or the wavelength, if you measure both you will get a divergence.
Awesome explanation. And intriguing in the context of this experiment. It seems that the debate here really has little to with quantum mechanics -- rather the concern is information transmission. To be honest, I am not sure how information transmission related to QM, especially (as you so thoughtfully pointed out) since that determinism in QM is strictly statistical. Presumably the statistical basis of QM determinism must have implications for the meaning of information transfer in the type of experiment presented here. Anne, Happyjack, and Felix seem to take the deterministic view of information transmission -- a message is created, propagates through a channel and is received at the other end. In contrast, Slowburn and Synchro seem to consider information in a quantum sense. I'm just speculating, but perhaps the two types of information are not the same. I would be delighted to here what you have say you about this, JSchlesinger. I hope you come back.