Physicists close two loopholes while violating local realism

Nov 30, 2010 by Lisa Zyga feature
Physicists performed a Bell experiment between the islands of La Palma and Tenerife at an altitude of 2,400 m. Starting with an entangled pair of photons, one photon was sent 6 km away to Alice, and the other photon was sent 144 km away to Bob. The physicists took several steps to simultaneously close the locality loophole and freedom-of-choice loophole. Image credit: Thomas Scheidl, et al. and Google Earth, ©2008 Google, Map Data ©Tele Atlas.

(PhysOrg.com) -- The latest test in quantum mechanics provides even stronger support than before for the view that nature violates local realism and is thus in contradiction with a classical worldview. By performing an experiment in which photons were sent from one Canary Island to another, physicists have shown that two of three loopholes can be closed simultaneously in a test that violates Bell's inequality (and therefore local realism) by more than 16 standard deviations. Performing a Bell test that closes all three loopholes still remains a challenge, but the physicists predict that such an experiment might be "on the verge of being possible" with state-of-the-art technology.

The physicists, who belong to the group of Rupert Ursin and Anton Zeilinger and were all at either the Austrian Academy of Sciences in Vienna or the University of Vienna when performing the experiments in 2008, have published their study on the new Bell test in the early edition of PNAS. As they explain in their study, local realism consists of both realism – the view that reality exists with definite properties even when not being observed – and locality – the view that an object can only be influenced by its immediate surroundings. If a Bell test shows that a measurement of one object can influence the state of a second, distant object, then local realism has been violated.

"The question of whether nature can be understood in terms of classical concepts and explained by local realism is one of the deepest in physics,” coauthor Johannes Kofler told PhysOrg.com. “Getting Bell tests as loophole-free as possible and confirming quantum mechanics is therefore an extremely important task. From a technological perspective, certain protocols of quantum cryptography (which is entering the market at the moment) are based on entanglement and violation of Bell’s . This so-called ‘unconditional security’ must in practice take care of the loopholes in Bell tests."

The physicists explained that, in experimental tests, there are three loopholes that allow observed violations of local realism to still be explained by local realistic theories. These three loopholes can involve locality (if there is not a large enough distance separating the two objects at the time of measurement), the freedom to choose any measurement settings (so measurement settings may be influenced by hidden variables, or vice versa), and fair sampling (a small fraction of observed objects may not accurately represent all objects due to detection inefficiencies).

Previous experiments have closed the first loophole, which was done by ensuring a large spatial separation between the two objects (in this case, two quantum mechanically entangled photons) so that measurements of the objects could not be influenced by each other. Special relativity then ensures that the objects cannot influence each other, since no physical signals can travel faster than the speed of light. In these experiments, classically unexplainable correlations were still observed between the objects, indicating a violation of local realism. (The fair sampling loophole was closed in another earlier experiment using ions, where large detection efficiencies can be reached.)

In the current experiment, the physicists simultaneously ruled out both the locality loophole and the freedom-of-choice loophole. They performed a Bell test between the Canary Islands of La Palma and Tenerife, located 144 km apart. On La Palma, they generated pairs of entangled photons using a laser diode. Then they locally delayed one photon in a 6-km-long optical fiber (29.6-microsecond traveling time) and sent it to one measurement station (Alice), and sent the other photon 144 km away (479-microsecond traveling time) through open space to the other measurement station (Bob) on Tenerife.

The scientists took several steps to close both loopholes. For ruling out the possibility of local influence, they added a delay in the optical fiber to Alice to ensure that the measurement events there were space-like separated from those on Tenerife such that no physical signal could be interchanged. Also, the measurement settings were randomly determined by quantum random number generators.

To close the freedom-of-choice loophole, the scientists spatially separated the setting choice and the photon emission, which ensured that the setting choice and photon emission occurred at distant locations and nearly simultaneously (within 0.5 microseconds of each other). The scientists also added a delay to Bob's random setting choice. These combined measures eliminated the possibility of the setting choice or photon emission events influencing each other. But again, despite these measures, the scientists still detected correlations between the separated photons that can only be explained by quantum mechanics, violating local realism.

By showing that local realism can be violated even when the locality and freedom-of-choice loopholes are closed, the experiment greatly reduces the number of “hidden variable theories” that might explain the correlations while obeying local realism. Further, these theories appear to be beyond the possibility of experimental testing, since they propose such things as allowing actions into the past or assuming a common cause for all events.

Now, one of the greatest challenges in quantum mechanics is simultaneously closing the fair-sampling loophole along with the others to demonstrate a completely loophole-free Bell test. Such an experiment will require very high-efficiency detectors and other high-quality components, along with the ability to achieve extremely high transmission. Also, the test would have to operate at a critical distance between Alice and Bob that is not too large, to minimize photon loss, and not too small, to ensure sufficient separation. Although these requirements are beyond the current experimental set-up due to high loss between the islands, the scientists predict that these requirements may be met in the near future.

“Performing a loophole-free Bell test is certainly one of the biggest open experimental challenges in the foundations of ,” Kofler said. “Various groups are working towards that goal. It is on the edge of being technologically feasible. Such an experiment will probably be done within the next five years.”

Explore further: A new multi-bit 'spin' for MRAM storage

More information: Thomas Scheidl, et al. “Violation of local realism with freedom of choice.” 19708-19713, PNAS, November 16, 2010, vol. 107, no. 46. DOI:10.1073/pnas.1002780107

4.7 /5 (61 votes)

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User comments : 81

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Question
1.7 / 5 (11) Nov 30, 2010
Where is the explanation as to how the experiment was carried out? Where are the results to prove their claim?
Honor
5 / 5 (14) Nov 30, 2010
read the journal if you want that info.
Question
1.7 / 5 (10) Nov 30, 2010
read the journal if you want that info.

Where is the link to the journal? The link at the end of the article doesn't have that information.
El_Nose
5 / 5 (11) Nov 30, 2010
dude stop being lazy - click the link - then read what is on the page -- there is a link to the paper they wrote -- full text pdf version just to the right of the abstract ...
NameIsNotNick
not rated yet Nov 30, 2010
read the journal if you want that info.

Where is the link to the journal? The link at the end of the article doesn't have that information.

Did you download the article or just read the abstract?
ArcainOne
5 / 5 (12) Nov 30, 2010
I understood maybe 10-20% of this article as I am not a physicist... however this is freaking cool. The more I learn about Quantum mechanics the more fascinating this universe turns out to be.
NotAsleep
3.7 / 5 (7) Nov 30, 2010
In the case of this experiment, it's my understanding that simply knowing the spin of one particle cannot ever affect or change the outcome of the other particle. The fate of both particles was determined the instant they were created hence no information is ever traveling at faster than the speed of light. What is the significance of this experiment? Is it just to show how good we're getting at measuring quantum entangled pairs in increasingly difficult situations?
Skeptic_Heretic
4.5 / 5 (14) Nov 30, 2010
What is the significance of this experiment?
Non-locality confirmation.
Is it just to show how good we're getting at measuring quantum entangled pairs in increasingly difficult situations?
No, a loophole free entanglement experiment rules out any sort of connection between the two particles over distance, thus proving that quantum mechanics defines reality. Basically it's like saying the Earth is round but never being able to prove it until you go to space and take a good look at it.

This is the lead up to the good look at it.
Tektrix
3.8 / 5 (12) Nov 30, 2010
In the case of this experiment, it's my understanding that simply knowing the spin of one particle cannot ever affect or change the outcome of the other particle. The fate of both particles was determined the instant they were created hence no information is ever traveling at faster than the speed of light. What is the significance of this experiment? Is it just to show how good we're getting at measuring quantum entangled pairs in increasingly difficult situations?


Not exactly. You can change the state of one member of the entangled pair and know that the other member will change in a correlated manner. You can alter the state of one member AFTER it has left the emitter and the other member will STILL remain correlated (will change states in immediate accord with the other).

This experiment added further evidence that there are no hidden classical variables that could account for this ability to retain a correlation between two entangled particles, regardless of distance.
Gawad
5 / 5 (6) Nov 30, 2010
Where is the explanation as to how the experiment was carried out? Where are the results to prove their claim?

For heaven's sake. Try here: http://www.pnas.o...pdf+html
Modernmystic
2.9 / 5 (8) Nov 30, 2010
I still can't grasp why this principle couldn't lead to FTL communications.

If you change the spin state of one you could say that's a 1, if you do nothing you could say that's a 0. That's the beginning of a digital signal isn't it?
Pyle
4 / 5 (5) Nov 30, 2010
@Tektrix - I think you have it a bit off.
You can alter the state of one member AFTER it has left the emitter and the other member will STILL remain correlated

I believe it is more correct to say you can measure one member and then know what the subsequent measurements on the other member will be. Before you measured it the value is undetermined due to the uncertainty principal. After measurement you "set" the value of both members. Unfortunately, I don't believe we currently have the ability to force a measurement, so we can't convey information using entanglement. However, I still don't fully understand the following article, so somebody step up and correct me if I am off.
http://www.physor...481.html
Gawad
5 / 5 (8) Nov 30, 2010
I still can't grasp why this principle couldn't lead to FTL communications.

If you change the spin state of one you could say that's a 1, if you do nothing you could say that's a 0. That's the beginning of a digital signal isn't it?
This would be correct...if you could "change" the spin state. But that's not quite what's happening. You're actually going from an undefined spin state to one that's either up or down (in the case of photons this will be polarization, though, as photons are spin 0), and you don't get to see the transition. In fact, prior to your interaction with the particle, whether you're Alice *or* Bob, its spin is both up and down (or horizontal and vertical in the case of a photon). Whoever interacts with it first sets both particles of the pair to complimentary values but all anyone ever actually sees is either an up or down spin or a vertical or horizontal polarization. You don't get to see it flip from one state to another so no FTL communication is possible.
NotAsleep
4.9 / 5 (7) Nov 30, 2010
Another way to say it would be that the spin is neither up nor down until we measure it and assign a value to it. The information exists from the point of creation but until the point of measurement the information is considered useless. The word "entanglement" might seem to imply that we can measure the spin of one, reverse that spin somehow and thereby reverse the spin of the other instantly. This isn't the case, though. As soon as the two particles leave the point of origin, one can no longer truly influence the other.

I like Skeptic Heretic's explanation of the importance
Gawad
4.9 / 5 (9) Nov 30, 2010
And it gets worse. The entanglement doesn't actually end when Alice or Bob has a peek at their particle, it just propagates to them. So if Bob peeked first you just end up with one Bob who saw a horizontally polarized photon (-), and another Bob who saw a vertically polarized photon (|). The really cool thing is that the same thing happens to Alice when she peeks at her photon, but only the Alice who saw the - photon will ever meet the Bob who saw the | photon. They share the same universe. And the Alice who saw the | photon will only ever meet the Bob who saw the - photon. They too share the same universe. Well, at least if you believe the Many Worlds interpretation of QM.
Question
2.3 / 5 (8) Nov 30, 2010
Thanks to everyone who pointed me to the link.

Test results no where near 100%. If one split a coin, heads from tails, and sent at random each in a different direction for a lightyear you would have 100% correlation. These two coin halves are not entangled in any way yet they have a much higher correlation than the polarized photons in this experiment. Conclusion, the photons are not entangled in any way, they are what they are from the moment they were created just like the two coin halves.

http://www.pnas.o...ion.html
NotAsleep
5 / 5 (2) Nov 30, 2010
So if two Bobs met one Alice in this universe, would Alice in another universe feel short changed?

If only they could just get along...
Husky
2 / 5 (1) Nov 30, 2010
could our difficulty of describing EXACTLY what is happening on quantum level with the same reproducable deterministic degree as Newton described the movement of planets,

May be due the possibillity? that quantum teleportation over a distance might no be some unusual exotic behaviour observed in a highly synthetic confined experiment within a very small number of particles,

ut in fact QT could be Standard Default mode of operation in wich ALL quanta at the atomic scale might interact in a possible deterministic way after all, but over a distance with other quanta, and that (contineud)
Husky
1 / 5 (1) Nov 30, 2010
it is just that there are so many small fragile quantums running around simultaniously in an atomic cloud the size of a dime that it could be the mere fetal stage of our technology that prohibits us currently from doing the zillions of simultanious minimal invasive measurements to compute and possibly reveal wich larger than pinpoint precision rules that can exactly describe cause and effect, like a newtonian description how billiard balls bounce, but then considering that some balls are acting over a distance with balls over thousands of other tables as,
Gawad
4.4 / 5 (7) Nov 30, 2010
Thanks to everyone who pointed me to the link.

Test results no where near 100%. If one split a coin, heads from tails, and sent at random each in a different direction for a lightyear you would have 100% correlation. These two coin halves are not entangled in any way yet they have a much higher correlation than the polarized photons in this experiment. Conclusion, the photons are not entangled in any way, they are what they are from the moment they were created just like the two coin halves.

http://www.pnas.o...ion.html
Sorry Question, but this is just plain wrong. http://encycloped...e+theory
http://puhep1.pri...5_76.pdf
http://www.scribd...theories
And on and on and on. HV theories make statistical predictions that don't line up with experiment. QM does. You're just going to have to learn to deal with it.
Husky
1 / 5 (3) Nov 30, 2010
quantum dynamics & quantumchromodynamics has been the working horse to now to uncover some method in the madness of the seemingly randomly vibrating quantum that refuses to be harnessed in a deterministic straightjacket, but only by repeated measuring of groups of quantumcolours/flavors to distill the general interaction of specific flavors as statistic group probabillity, wich been good enough to build reliable nuclear reactors because a sea of tiny uncertainties levels/averages out on the macro scale into a predictable reactor heatflow of deterministic precision, but if we want it take it to the next level, for instance spaceships with quantum teleportation engines, that get their reaction mass and reaction energy remotely beamed, we need to dissect the elusive quantum further and get the full detailed teleport tunnel dynamics, in terms of geometry, communication modes, maybe the LHC is just what has the beam and computing power to reveal this kind of detail in gluon-quark plasma
Husky
2.7 / 5 (3) Nov 30, 2010
Gawad i am still sitting on the bench whether or not realtime FTL interaction is possible, but if not, if indeed we cannot observe or induce a remote polarity flip, but merely take seperate peeks to make an educated guess, about the predetermined particle states already cresulting from during their previous action,

Husky
2 / 5 (4) Nov 30, 2010
than i honestly ask myselve what on earth are these scientists setting up these complicated eleborate experiments use hard abstract language to replicate what looks like handing out two sealed envelopes to Bob and Alic, one with money, one with newspaer scraps, and Bob will open the envelope only to assume that Alice got away with the money from the start, and even that conclusing from Bob, does not operate any further spookier than the local reality inside his skull as a neural pattern describing a conceptual cloned representation of Alices envelope but not the actual renote reality of a money containing envelope, wich actually could alreasy be accidentely burned by alice, underscoring thats Bobs measuring of his own reality does only allows him to make an educated guess upon limited preceding information, is there something more QT experiments to keep me excited other than researchers widely insinuating the existence and soon to be tunable teleport tunnel?
Question
2.8 / 5 (8) Nov 30, 2010
Gawad, its nonsense, Einstein was right.
physpuppy
not rated yet Nov 30, 2010
Off topic:
@NotAsleep :

You made me think of a movie from 1969:
Bob & Carol & Ted & Alice
http://www.imdb.c...tsummary
Zed123
4.3 / 5 (11) Nov 30, 2010
Gawad, its nonsense, Einstein was right.


Its not nonsense. You just don't understand it.
Skeptic_Heretic
5 / 5 (13) Nov 30, 2010
Gawad, its nonsense, Einstein was right.

Only half right. QM has produced the most accurate predictions to date within all the fields of science. If it is wrong, tell me how you get an accurate mass for a proton with GR.

Its not nonsense. You just don't understand it.
No one really understands it. Anyone who says different is a liar.
DamienS
5 / 5 (12) Nov 30, 2010
No one really understands it. Anyone who says different is a liar.

That's why I love physics. The nature of reality remains eminently mysterious even as we continue to learn more and more about it. Who needs fiction when you have reality?
tkjtkj
1 / 5 (3) Nov 30, 2010
Let me get this straight: the authors, attempting to show that Relativity's rules don't apply in their scenarios then go on to use Relativity (ie, 'no FTL') to prove it??
Gawad
5 / 5 (1) Nov 30, 2010
(in the case of photons this will be polarization, though, as photons are spin 0)
Eeech. Sorry, I just reread that. My bad. Photons are spin 1. Anyway, point being only fractional spin particles can have positive or negative spin direction (up or down) which is why polarization is used for photons.
Gawad
4.7 / 5 (3) Nov 30, 2010
Gawad i am still sitting on the bench whether or not realtime FTL interaction is possible, but if not, if indeed we cannot observe or induce a remote polarity flip, but merely take seperate peeks to make an educated guess, about the predetermined particle states already cresulting from during their previous action,
I seriously doubt FTL interaction will ever be possible, properly speaking, and certainly not this way, but other types of work-arounds have already been proposed using negative energy and space-time warping. I still think its a longshot, but the fat lady ain't sung yet. Human creativity never fails to astound AFAIC.
Gawad
not rated yet Nov 30, 2010
...what on earth are these scientists setting up these complicated eleborate experiments use hard abstract language to replicate what looks like handing out two sealed envelopes to Bob and Alic, one with money, one with newspaer scraps, and Bob will open the envelope only to assume that Alice got away with the money from the start, and even that conclusing from Bob, does not operate any further spookier than the local reality inside his skull as a neural pattern describing a conceptual cloned representation of Alices envelope but not the actual renote reality of a money containing envelope, wich actually could alreasy be accidentely burned by alice, underscoring thats Bobs measuring of his own reality does only allows him to make an educated guess upon limited preceding information, is there something more QT experiments to keep me excited other than researchers widely insinuating the existence and soon to be tunable teleport tunnel?
Well, there you go, that's it exactly, yup.
Gawad
5 / 5 (4) Nov 30, 2010
Gawad, its nonsense, Einstein was right.

I happen to agree with you, insofar as it's absolutly nuts. Yet it does appear to accurately describe how the fundamental building blocks of existance behave. In addition, or rather because of that it also speaks, IMO, to something very profound about our reality that we have yet to grasp.
Gawad
5 / 5 (3) Nov 30, 2010
Gawad, its nonsense, Einstein was right.


Its not nonsense. You just don't understand it.

Also true. I mean, we can do the math and get the right answers, but then again, as Skeptic says, nobody really understands it. Sure there are lots of interpretations floating around, but that's precisely because what QM proposes clashes directly with common experience.
Gawad
4.8 / 5 (6) Nov 30, 2010
Let me get this straight: the authors, attempting to show that Relativity's rules don't apply in their scenarios then go on to use Relativity (ie, 'no FTL') to prove it??
Special Relativity and QM get along just fine, which is what the authors were dealing with. That'll get you relativistic quantum field theories. QM and General Relativity, well that's a whole other problem.
Attitude_CHECK
not rated yet Dec 01, 2010
The experiment described would only seem to demonstrate non-local causality. That has nothing to do with "realism" as defined in the article.
hourifromparadise
1 / 5 (3) Dec 01, 2010
A proof for a loophole-free Bell-test , is nothing more than the proof ,that there is "something" irrelative to the space-time-continuum. Why is it so strange that there exists "that" what is not limited or bordered by space , time and matter.
People talk a lot about God , which in their opinion is also limitless ,timeless ,beginningless , etc.
Skeptic_Heretic
5 / 5 (6) Dec 01, 2010
Why is it so strange that there exists "that" what is not limited or bordered by space , time and matter.
People talk a lot about God , which in their opinion is also limitless ,timeless ,beginningless , etc.
Please don't try to use entanglement to prove a god figure, you'll only serve to be completely annoying.
Aristoteles
not rated yet Dec 01, 2010
Photon has spin 1 !!!
hourifromparadise
1 / 5 (4) Dec 01, 2010
@skeptic heretic . I am talking of people not of myself . I only mention a behaviour of people . Your reaction seems a bit arrogant to me .Why don't you react about my first sentence . What is that , what is not relative to space , time and matter ?
A loophole-free Bell test would be the proof of that ,or would you be annoyed with such a result.
Gawad
not rated yet Dec 01, 2010
Photon has spin 1 !!!
I know. See my correction above. I either had a neuron misfire while thinking of the Higgs or hit the 0 below the 1 key.
nxtr
1 / 5 (4) Dec 02, 2010
The only really cool thing to do with this violation of local nonrealism is faster than light communications, no matter what type of crude hack system it is, it should work if the new QM laws hold true at this distance, i really don't see why they wouldn't hold true across the universe.
DanV
1 / 5 (1) Dec 02, 2010
I wrote an email to Anton Zeilinger. I suggested that using a random generator to eliminate choice is not closing the loophole, because alo a generator is designed and programmed by a human-being who had choice.
Skeptic_Heretic
5 / 5 (5) Dec 03, 2010
I wrote an email to Anton Zeilinger. I suggested that using a random generator to eliminate choice is not closing the loophole, because alo a generator is designed and programmed by a human-being who had choice.
That's not accurate. A random number generator removes arbitrary values, thus removing the interaction of choice. This isn't some form of philosophical choice argument we can mount against the result.
bobhuang
2 / 5 (2) Dec 04, 2010
Do not understand all. Do love it and will do more research. This relates to my interest in our ability to "see". The visible world through our vision is the past. We do know that present exists. Is the future also exists inthe space time continumm even though we cannot "see"?
Question
1 / 5 (3) Dec 04, 2010
There is nothing unexplainable about these types of entanglement experiment because there is nothing entangled.

Here is a way to prove it, have a sender and observers A and B receiving the two entangled polarized photon.
The sender would send the split polarized photons with a new twist, he would send them at random to observers A and B. The difference is the sender would know which photon he sent to A and B. And he could predict with 100% accuracy which photon each receiver would detect BEFORE they detected it.

Now my question is how could the sender possible know this IF the two polarized photons are in both states after they are sent but before they are received?
Tristan_Caley
3 / 5 (2) Dec 05, 2010
Sometimes I wonder if these physicists are just bullshitting us all and using the money we give them to buy sheets of LSD so they can trip balls for a few hours while they come up with fancy-sounding crap to confuse the normal people.

Then I remember that our universe is fucking awesome.
bluehigh
1 / 5 (3) Dec 05, 2010
Faster than light information transfer happens. A lot. Its experimentally demonstrable and does not need entanglement to occur (unless by re-definition). There is a discussion in New Scientist Last Word feature regarding the logic. It may take some time for mainstream physics to acknowledge the fact due to the baggage of intellectual investment but to deny the fact is to remove logic from science methodology. What cant be done (so far) is move mass faster than light speed.
Skeptic_Heretic
3.7 / 5 (3) Dec 05, 2010
Faster than light information transfer happens. A lot. Its experimentally demonstrable and does not need entanglement to occur (unless by re-definition).
An example please?
bluehigh
2 / 5 (4) Dec 05, 2010
@Skeptic
True random number generators likely do not exist. We, as you would know, rely on very long and obscure patterns to produce Pseudo random numbers. In fact true randomness may simply not exist, if you want to get philosophical. Even atomic or chemical sources are based on causal elements. Scientific American many years ago in Mathematical Games, demonstrated a pattern recogition algorithm and supporting analysis that showed at best ALL supposedly random numbers generators had rare but detectable patterns. My doctoral thesis was based partly on the application of the math when related to electronic motion in semiconductors (in particular Thermal Noise). Although elements of any sequence are determinstic that's not to suggest that any form of manipulable choice occurs.
soulman
2.7 / 5 (7) Dec 05, 2010
True random number generators likely do not exist.

http://www.random...bout.htm
hourifromparadise
1 / 5 (3) Dec 05, 2010
True randomness only exists in the world of quantum-mechanics.
Max Planck institute for the physics of light in Erlangen , Germany.
Nature photonics (august 29 , 2010).
Skeptic_Heretic
3 / 5 (2) Dec 05, 2010
@Skeptic
True random number generators likely do not exist.
They do, see above.
We, as you would know, rely on very long and obscure patterns to produce Pseudo random numbers.
No, we don't, and computers don't.
In fact true randomness may simply not exist, if you want to get philosophical.
Again, as I said above, I do not, nor do we need to.
Even atomic or chemical sources are based on causal elements.
Everything, and I mean everything, is based on causal sources.

The amount of randomness needed does exceed me saying to you "pick a random number, between 1 and 5". This entire process is causal, the chemical reactions in the relevant parts of your body that facilitate your mental ability to do anything are causal.

When repeating the experiment, with an entirely different RNG, you'll get the same results. Randomness achieved.
True randomness only exists in the world of quantum-mechanics.
Even that is causal. We simply don't know the causes yet.
hush1
5 / 5 (1) Dec 05, 2010
Everything, and I mean everything, is based on causal sources.


Even that is causal. We simply don't know the causes.


Speaking only for myself, this appeals to me at least.

Sort of like an 'absolute reference' to rid one-self's of expressions like:
"uncaused causes" or "sourceless sources"

Almost sad to part from literary expressions, expressing oxymora. As if the literary world becomes poorer with the loss of such expressions from which the literature of science appears to benefit.

The concept "everything causal" makes randomness meaningless. I wonder what spored the need to invent the word randomness? Maybe the word is shorthand for:
We simply don't know the causes yet.
hush1
not rated yet Dec 05, 2010
I wonder what spored the need to invent the word randomness?


To answer my own question with a question:
Perhaps the concept "free will" spored the need to invent the word "randomness"?
The motivation to have free will motivates the need to invent the word randomness. A conjecture that made sense until now.
Ethelred
5 / 5 (4) Dec 05, 2010
Yes. But what does that have to do with producing an example of FTL information transfer?

Last I heard the best way to generate real random numbers is with a radioactive source. In theory this should be true randomness if anything can be. And I still don't see how that would have anything to do with FTL information transfer.

Ethelred
Skeptic_Heretic
1 / 5 (1) Dec 05, 2010
The concept "everything causal" makes randomness meaningless. I wonder what spored the need to invent the word randomness? Maybe the word is shorthand for:
We simply don't know the causes yet.
That's my take on it. A lack of knowledge doesn't mean something is unknowable. "Random" is simply a synonym for unknowable in my book. Neither is true given enough time and effort.
Ethelred
not rated yet Dec 05, 2010
The concept "everything causal" makes randomness meaningless.
I am not sure that SH meant it that way. That things have causes does not require the results of those causes to be non-random.

To give a not truly random example.

Throw a die. The CAUSE is the throw and then the collision. The result will be random, well not really random but this is an analogy.

In the example on
http://www.random...ting.htm

The cause is a photon generator and a beam splitter. There the result is truly random IF we aren't full of it about QM. It might be interesting to run this setup for a LONG time and test the results against those expected for true randomness.

Ethelred
genastropsychicallst
1 / 5 (6) Dec 05, 2010
Z twistor h-boson squark w twistor h-boson, extraterrestrial l-boson. To be read on my website, Albert.
Ethelred
4 / 5 (4) Dec 05, 2010
I gave the Monkey-typewriter bot a one because of the lie at the end. There is only the same word wooze on the the site. There is nothing there but a long list of disconnected words and NOWHERE is a sign of the purpose of the site.

It reminds of the way sites used to paste an outhouse load of key words the same color as the background in an attempt to baffle the Pre-Page Rank search engines. VERY popular with porn sites.

Perhaps Albert Monkey is planning to create a science porn site. Full of tempting voluptuous words like 'intermediate vector boson' and penetrating insight into the darker aspects of the bio-physics of pheromones. I can't wait to download videos of Black Hole on Neutron Star action with their pulsating gravity fields in sensuous false colors. The turgid prose of PhD's engaging in white-board showers of multicolored pens.

Posts like this are a sign that I need to go to sleep.

Ethelred
tkjtkj
2 / 5 (1) Dec 05, 2010
The concept "everything causal" makes randomness meaningless.
... It might be interesting to run this setup for a LONG time and test the results against those expected for true randomness.

Ethelred


err... Now, just *how* would one be able to predict an 'acceptable' result as a consequence of "true randomness" ..
It boggles the mind..
tkjtkj
1 / 5 (1) Dec 05, 2010
Yes. But what does that have to do with producing an example of FTL information transfer?

Last I heard the best way to generate real random numbers is with a radioactive source. In theory this should be true randomness if anything can be. And I still don't see how that would have anything to do with FTL information transfer.

Ethelred


Sorry, but that approach has been ruled out by recent observations that rates of decay are NOT constant .. They change, on earth, with the position of earth relative to Sol in its yearly cycle.

Wish i had the ref, but i believe it was presented here not long ago ..
yyz
5 / 5 (8) Dec 05, 2010
"Sorry, but that approach has been ruled out by recent observations that rates of decay are NOT constant .. They change, on earth, with the position of earth relative to Sol in its yearly cycle."

I think this is the finding you're referring to: http://arxiv.org/...83v1.pdf

This is still an unsubstantiated claim at this time IMO. Especially in light of this finding by a separate group: http://arxiv.org/...3265.pdf
Pyle
3.5 / 5 (2) Dec 05, 2010
@yyz,
That's for that link. I was still having heartburn over Jenkins finding from that previous article. Good to know it isn't settled yet.
Pardon the repost, but anybody got any thoughts on the following story as it relates to FTL communication and this one?
http://www.physor...481.html
Reminds me of the information = energy Maxwell's demon.
theon
5 / 5 (1) Dec 06, 2010
The contextuality loophole cannot be closed. So violation of Bell inequalities has no consequences for local realism.
T. M. Nieuwenhuizen, Foundations of Physics, Online First™, 11 May 2010
theon
not rated yet Dec 06, 2010
The contextuality loophole cannot be closed. So violation of Bell inequalities has no consequences for local realism.
T. M. Nieuwenhuizen, Foundations of Physics, Online 11 May 2010.
Skeptic_Heretic
1 / 5 (1) Dec 06, 2010
The contextuality loophole cannot be closed. So violation of Bell inequalities has no consequences for local realism.
T. M. Nieuwenhuizen, Foundations of Physics, Online 11 May 2010.
The initial problem I see here, and I could be wrong (Please correct me if that is the case), is the fact that contextuality has a speed limitation of information, which unless you're proposing that information propagates FTL, requires a time delay within entanglement related to locality.
Pyle
1 / 5 (1) Dec 06, 2010
I am confused. SH, why does the speed limitation of contextuality hurt Nieuwenhuizen's explanation? I think he contends that violation of Bell's inequality demonstrates that the probability distributions of different measurements aren't equal, rather than demonstrating local realism being violated.

Intuitively I want to believe @theon's quoted paper to remove the "spooky action at a distance." Get ready for an inappropriate analogy. Somebody shoot me down if I hose it.

Pyle
1 / 5 (1) Dec 06, 2010
Pennies halves in envelopes. 100% negatively correlated on heads/tails. 100% correlated on composition. Let's say that some possible measurements are heads or tails, %composition of copper, %comp of zinc, etc.

The probability distributions governing the different measurements are not equal, obviously. Take it back to QM and our discussion.

According to Nieuwenhuizen, Bell's Inequalities make the assumption that the probability space for all measurements are the same. He contends that violation of the Bell Inequalities shows that this assumption is invalid, rather than violating local realism. i.e. the hidden variable of "source mint" lets you know the composition probability space for your experiment, but doesn't change the heads/tail distribution.
Skeptic_Heretic
3 / 5 (2) Dec 07, 2010
I am confused. SH, why does the speed limitation of contextuality hurt Nieuwenhuizen's explanation? I think he contends that violation of Bell's inequality demonstrates that the probability distributions of different measurements aren't equal, rather than demonstrating local realism being violated.
Sorry for the delay, basically we have observed that in order for Nieuwenhuizen's explanation to be correct, that means that information must travel faster than light. Effectively N has violated relativity unless he can explain the mechanism by which the entanglement is broken. So you have two paths: locality which requires FTL information transfer or non-locality which requires nothing.

You keep looking at this as a split coin, it isn't a split coin. It is two sink washers that become either the head or tail of the coin independently on the entanglement break. You can have two heads, two tails, or a mix. One doesn't demand or force the opposite.
Pyle
1 / 5 (1) Dec 07, 2010
How do we know that it isn't more like the split coin, rather than "spooky action at a distance"?

N's whole point, I thought, was that the Bell test doesn't tell us. My understanding is that we can't observe dual spin-ness on the entangled particles to show that they are undecided prior to measurement. If Bell's test is flawed as N states, why can't hidden variables (1 or more) be determining the spin and there NOT be the FTL transfer.

I don't think N is saying entanglement doesn't work. But I think the point is he feels the test is flawed. Just like the concentric CMB rings don't necessarily provide evidence for or against CCC.
Skeptic_Heretic
3 / 5 (2) Dec 07, 2010
If Bell's test is flawed as N states, why can't hidden variables (1 or more) be determining the spin and there NOT be the FTL transfer.
That's irrelevant. How does one side know the exact moment that the other is disentangled? That's the problem. N's whole point is good an all, but he violates the HUP (which I don't have a problem with) then he violates relativity (which I have a big problem with).
Gawad
5 / 5 (3) Dec 07, 2010
Faster than light information transfer happens. A lot. Its experimentally demonstrable and does not need entanglement to occur (unless by re-definition). There is a discussion in New Scientist Last Word feature regarding the logic. It may take some time for mainstream physics to acknowledge the fact due to the baggage of intellectual investment but to deny the fact is to remove logic from science methodology. What cant be done (so far) is move mass faster than light speed.
It's worth noting that you haven't yet answered S_H's question, Bluehigh. I was waiting with bated breath. What FTL information transfer happens a lot? What experiments demonstrate this incredible phenomenon that goes against all known and widely accepted physics? What New Scientist Last Word feature makes reference to this? Are you just blowing smoke? Humm. Thought so.
CHollman82
3 / 5 (2) Dec 07, 2010
Whoever interacts with it first sets both particles of the pair to complimentary values


Wait wait wait...

If we operate under the assumption that these particles are entangled, then detecting the spin state of one gives you knowledge of the spin state of the other... I understand that, it would seem obvious.

But, you aren't SETTING the spin state of either... Just because you don't know what spin state either are in does not mean they aren't in any, that's just a thought experiment a la shrodingers cat... It's an analogy, it does not necessarily reflect reality.

The two entangled particles have a spin state, you don't know what that is. You determine the spin state of one, and since they are entangled you then know the spin state of the other... that is all that is going on.

And if we cannot exert influence on these entangled particles I really don't understand how they are claiming a violation of locality. Could it not also be looked at as a confirmation of determinism?
Gawad
5 / 5 (1) Dec 07, 2010
Whoever interacts with it first sets both particles of the pair to complimentary values


Wait wait wait...

If we operate under the assumption that these particles are entangled, then detecting the spin state of one gives you knowledge of the spin state of the other... I understand that, it would seem obvious.

But, you aren't SETTING the spin state of either... Just because you don't know what spin state either are in does not mean they aren't in any, that's just a thought experiment a la shrodingers cat... It's an analogy, it does not necessarily reflect reality.
Well, I'll admit that the word "set" is imperfect as it may lead one to think the observer has a choice in the matter, which AFAIK isn't the case. However, no, in QM it's not just a question of the observer not knowing what the entangled value is. In QM it's a matter of there not BEING a definite value until an interaction takes place. It's a form of superposition of quantum states, of quantum values.
Gawad
not rated yet Dec 07, 2010
Just because you don't know what spin state either are in does not mean they aren't in any, that's just a thought experiment a la shrodingers cat... It's an analogy, it does not necessarily reflect reality.
Actually, the results of experiments comparing the statistical predictions of QM vs. Hidden Variables theories (what you are proposing in your post) demonstrate exactly the contrary: QM *is* a valid description of reality while HV theories are not. I posted a set of links to mainstream and classic papers somewhere above that deal with precisely that.

The two entangled particles have a spin state, you don't know what that is. You determine the spin state of one, and since they are entangled you then know the spin state of the other... that is all that is going on.

And if we cannot exert influence on these entangled particles I really don't understand how they are claiming a violation of locality. Could it not also be looked at as a confirmation of determin
Gawad
not rated yet Dec 07, 2010
Heck, the last two paragraphs in my last post are CHollman's, not mine. They were supposed to be truncated but made it back anyway.
Quantum_Conundrum
1 / 5 (1) Dec 07, 2010
That's not accurate. A random number generator removes arbitrary values, thus removing the interaction of choice. This isn't some form of philosophical choice argument we can mount against the result.


IN this case, I would disagree.

Generating "true" random numbers is virtually impossible, and in any case, a "choice" about just how to do that was also made.

Whether to do the experiment at all is, after all, a choice.
seb
not rated yet Dec 08, 2010
If the state of one photon is "set" by the measurement, "causing" the other photon to correlate to that measurement, could that not be used as a one-off consumable long distance transmission? In that pre-established 'measurement influences' are used, such that to send 1 you use one kind measurement, and to send 0 you use a different kind of measurement (known to set a different state), at the source, and at the destination, the 'state' of the photon tells you what measurement was used?

You wouldn't be changing the spin state on the fly, just using the way the measurement influences the 'observed state' of the photon, and once that particular photon pair is measured, it's thrown out and a fresh unmeasured one is used?

Obviously it would mean you would have to generate and transport the photon pairs before hand, so for FTL types of scenarios, you'd still have to slow-boat it before-hand. If that worked it would have good applications for say, disposable interstellar space probes..
Skeptic_Heretic
3.7 / 5 (3) Dec 08, 2010
seb: you have no idea what the measured result will be, and no way in which to ensure any form of result. Meaning: after the entanglement break you must compare the two ends to ensure accuracy of result, and that must be done at sub-FTL.

Entangled photon pairs have no value, not a fixed value, none whatsoever. When you make the measurement, you get a value. Until you compare the two, you have zero information.
Pyle
3 / 5 (2) Dec 08, 2010
seb: Uncertainty. QM says prior to measurement you have a photon of UNDETERMINED spin. The entanglement break "determines" both photons' spins. The problem is we don't have a method to "observe" it without measuring it. Unless you have outside information that is limited by the speed of light, you don't know if the other photon was even measured. It is only after you compare results, via sub-FTL, that you see they were entangled.

The HV theory is that the spin is predetermined before the measurement, where as QM says it isn't. i.e. uncertainty. If QM is right, then we have "spooky action at a distance". So far no HV theory can match QM's accuracy. Physicists are trying to close the three loopholes in a single experiment because this will help validate QM.