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Making Sure Our Lab Equipment Isn't Tricking Us

Soulskill posted about a month ago | from the ghost-in-the-machine dept.

Science 108

An anonymous reader writes "In a newly published paper, MIT researchers propose an experiment that may close the last major loophole of Bell's inequality. The test is to see whether, as far-fetched as it sounds, a particle detector's settings conspire with events in the shared past to determine which properties of a particle to measure — a scenario that implies that a physicist running the experiment does not have complete free will in choosing each detector's setting. MIT’s David Kaiser says, 'It sounds creepy, but people realized that's a logical possibility that hasn't been closed yet. Before we make the leap to say the equations of quantum theory tell us the world is inescapably crazy and bizarre, have we closed every conceivable logical loophole, even if they may not seem plausible in the world we know today?' The test involves quasars, telescopes, and lots of deep, deep space. It was published this week in the journal Physical Review Letters (pre-print available at the arXiv)."

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108 comments

Please! (5, Funny)

NotQuiteReal (608241) | about a month ago | (#46303957)

Don't anthropomorphize the machines. They hate that, and will go back into their past to get you!

Re:Please! (0)

Anonymous Coward | about a month ago | (#46304303)

You're just putting off the inevitable.

Re:Please! (0)

Anonymous Coward | about a month ago | (#46304731)

You know how the large scale structure of the universe seems to be "large voids surrounded by thin walls of galaxies" right?

http://skyserver.sdss.org/dr1/en/astro/structures/structures.asp

Each of those voids is a region where some uppity almost-intelligent species managed to ask a question that offended the universe.

How about not-quite-random numbers? (1)

Lord Crc (151920) | about a month ago | (#46304085)

Why can't they use a PRNG to dictate the detector settings? Pick a high quality PRNG, seed it with the first prime number. Run the experiment N times. Restart, seeding it with the second prime number, and run the experiment for N times again. Repeat M times until satisfied.

Then re-run the above with a different type of high quality PRNG.

Am I missing some big clue?

Re:How about not-quite-random numbers? (1)

Anonymous Coward | about a month ago | (#46304191)

Who comes up with the formula for the PRNG? "They" could've conspired to choose a convenient PRNG a few decades ago. So you move from ms to decades. The authors's approach moves by 20 orders of magnitude in the past.

how about detector poisoning? (4, Interesting)

swschrad (312009) | about a month ago | (#46304545)

a much simpler explaination... the detector material is still groaning from the last collision and doesn't have its calibrated act together for the next one. you detect subatomic particles, after all, by watching what happens when they distort a known material, and extrapolate from the distortion what whacked into it. whacking things causes them to go off kilter. from black bands and reduced light in fluorescent light tubes to bright-bloom in old TV cameras to getting wacky when you leave a dark room and are sun-blinded, this has been a known phenonema as long as we have been around.

Re:How about not-quite-random numbers? (3, Interesting)

Immerman (2627577) | about a month ago | (#46305201)

AC has it right - *any* source of (psuedo)random numbers from causally connected sources is suspect, and no number of repetitions will rule out forces that retroactively ensure consistency. Frank and Bob could be simultaneously flipping coins on the opposite side of the planet, yet still be causally connected by the fact that their results will determine the settings for an experiment that the universe decrees must be consistent with certain principles. Even this experiment won't be able to close the loophole completely - it could be that the experiment and its settings were already fully defined in the first few instants of the universe while the not-matter that would eventually become the quasars was still causally connected. Basically this is a negative-evidence only experiment - it can't show that hidden variables aren't controlling QM, but it could potentially show that they are. Unless of course the hidden variables ensure that the choice of quasars will be such that the experiments yield consistent results. Though if they do it multiple times with different quasar pairs the odds of that being possible drop dramatically.

Re:How about not-quite-random numbers? (1)

maxwell demon (590494) | about 2 months ago | (#46309885)

What if they seed the PRNG with cosmic ray data? And/or XOR the PRNG with cosmic ray data?
I think if that also shows Bell correlations, it would only leave two possibilities:
* Either there's a god-like entity determining the results and actively misleading us. In which case, no amount of experimenting would help.
* Or quantum mechanics is right.

OK, there's third one:
* Actually the correlations don't really exist, but due to an extremely unlikely sequence of events the data still looks like we have one (similar to how a fair coin can land on the same side a million times in a row; it's just that it is so unlikely that we'd not believe that the coin is really unbiased if it happened; obligatory link [dilbert.com]).

Well, there's also a fourth one:
* Quantum mechanics as such is wrong, but we have parallel universes with an analogue of quantum suicide, and some extraterrestrial race wants to prevent us from discovering the true laws (because those would lead us to powerful weapons and thus make us a threat to them), and immediately vaporizes the earth as soon as a measurement violates quantum mechanics. Therefore in all surviving copies of the earth, the laws of quantum mechanics seem to hold.

OK, I guess I should stop before my possibilities get even more silly. ;-)

Re:How about not-quite-random nums? how about FTL? (1)

lucien86 (917502) | about 2 months ago | (#46312583)

Or a fifth one that General Relativity is incorrect and the universe follows an FTL model. In this case the present exists and so is fixed but the past does not literally exist (except as the integrated information state of the present) and so is basically flexible, as is the state of the future. Bells theorem does not apply to FTL theories anyway because they can go beyond local (STL) variables to absolute contexts - .

I have been working on an FTL model for ten years and it actually puts quantum mechanics as the only part of physics that actually exists - it locks relativistic space time to the quantum scale (4D at quantum scales, 3D at classical scales) - and it unifies FTL and quantum mechanics and relativity together into a single system. One problem is that C does not simply remain a simple constant but becomes a complex variable with directionality and complex multiple values in different contexts, one result of this is that the sharp division between FTL and STL physics is broken and our physics is actually a mixture of STL and FTL behaviour. (for FTL objects C is a minimum and limits at zero velocity)
Another bigger problem is that the model breaks current algebra (using permutation) and this leaves it with a lot of broken mathematical wiring. The whole thing is based on the ridiculously simple equation 1 x -1 = -1 = i.. numbers simply need to contain internal superposition to make imaginary numbers work.. One interesting example is that zero is redefined as an imaginary number - and all imaginary numbers can be summed as zero - which redefines all photons as (imaginary mass) tachyons and reduces all EM waves to FTL behaviour of particles.
There are obviously still many open problems and the work is only half finished. . .

searching for the obvious? (1)

virchull (963203) | about a month ago | (#46304101)

This is an elaborate experiment that will prove - we don't know everything in physics, yet. Seems like there are better ways to spend your time and creativity.

Re:searching for the obvious? (0)

Anonymous Coward | about a month ago | (#46304183)

Until you can break the standard model, sigma 5, peer reviewed with plenty of evidence... do shut up.

Re:searching for the obvious? (1)

i kan reed (749298) | about a month ago | (#46304209)

I don't think you realize how expensive it usually is to do experimental physics that pushes the bounds of our understanding. This sounds like it'll be cheaper than particle accelerator experiments, and may yield unexpected results.

Expected results are good too, then we can move on.

again with the assumptions. (4, Interesting)

clovis (4684) | about a month ago | (#46304117)

From the article:
The idea, essentially, is that if two quasars on opposite sides of the sky are sufficiently distant from each other, they would have been out of causal contact since the Big Bang some 14 billion years ago, with no possible means of any third party communicating with both of them since the beginning of the universe — an ideal scenario for determining each particle detector’s settings.

Why would you assume that if they're 14 billion years apart that it would be any different than 14 seconds apart in time, at least in regard to entanglement?
" with no possible means of any third party communicating" makes me think "we don't know of a means to communicate"
Could the outcome of the experiment could show either action at a distance, or some faster-than-light communication without excluding either possibility?
If it does happen that entanglement went away, it would be most interesting.

Re:again with the assumptions. (3, Interesting)

Goldsmith (561202) | about a month ago | (#46304187)

Exactly right.

There are two possibilities:
1) The universe is infinite, and it would be possible to find two quasars which never shared a quantum state.
2) The universe is not infinite and it is not possible to find two of anything which have never shared a quantum state.

They've completely failed to close this loophole.

Re:again with the assumptions. (1)

Anonymous Coward | about a month ago | (#46304305)

They're not looking for quasars with no shared quantum state, they're looking for quasars with no shared history. As in, outside of eachother's past light cone. The goal is to prove that there's no classical explanation for the observed excess in violation of Bell's inequality.

Re:again with the assumptions. (1)

Immerman (2627577) | about a month ago | (#46305247)

Yes, but the point is that, given a non-infinite big-bang origin, there's no such pair of quasars in existence - *all* the "stuff" that eventually became matter and quasars was causally connected for the first few instants of the universe. Assuming everything remains consistent with QM this just sets a really high lower limit on the strength of any free-will nullifying effects.

Or not - how exactly are the quasars chosen? Nullification need only be strong enough to ensure the "right" independent sources are chosen to ensure the "proper" outcome.

Re:again with the assumptions. (1)

sexconker (1179573) | about a month ago | (#46305801)

They're not looking for quasars with no shared quantum state, they're looking for quasars with no shared history. As in, outside of eachother's past light cone. The goal is to prove that there's no classical explanation for the observed excess in violation of Bell's inequality.

All light cones lead to the big bang, if you believe in that sort of thing.

Re:again with the assumptions. (0)

Anonymous Coward | about a month ago | (#46304441)

I'm guessing we'll see your rebuttal paper in Physical Review Letters soon then?

Re:again with the assumptions. (1)

maxwell demon (590494) | about 2 months ago | (#46309907)

Even if the universe is infinite, the observable part of it is finite, and there's evidence (the homogeneity of the cosmic microwave background) that all of it was once causally connected. A quasar that is outside the observable part of the universe won't help you because you can't use anything it emits — it doesn't reach you.

Re:again with the assumptions. (4, Insightful)

MozeeToby (1163751) | about a month ago | (#46304249)

You cannot have entanglement without interaction, you cannot have interaction between two things that lie outside of each other's light cones.

To be fair, you can't have interaction outside of your light cone without also having faster than light communication. But you can't have faster than light communication without also having the possibility of sending messages back in time. And you can't have the possibility of sending messages back in time without breaking causality. So, on the one side you have the assumption that causality doesn't exist and faster than light communication is possible (both of which are contradicted on scales from pico-meters to billions of lightyears), on the other side you have the assumption that information can't travel faster than light (which again, seems to be supported by every experiment and observation made in human history).

Re:again with the assumptions. (0)

Anonymous Coward | about a month ago | (#46304625)

Not quite. Entangled particles 21 Kilometers apart seem to communicate faster than the time light would take to cross the distance. Also, electrons in a semi-conductor often appear on the other side of the barrier before they have left the first side. As Bohr said "If you are not disturbed by quantum mechanics, than you don't really understand it."

Re:again with the assumptions. (0)

Anonymous Coward | about a month ago | (#46304851)

Neither example you gave violates causality though. The "communication" that happens via entanglement doesn't carry information in any way that break causality, while tunneling also doesn't break causality as the leading edge of the wavefunction you already emitted is what can cause the particle to appear on the other side of the barrier.

Re:again with the assumptions. (2)

camperdave (969942) | about a month ago | (#46305243)

How do entangled particles "seem" to communicate? Everything I've ever read points to one particle just being the opposite of what the other one is (eg. up spin on one, down spin on the other).

Re:again with the assumptions. (0)

Anonymous Coward | about a month ago | (#46306507)

Look at what happens when you take those two opposite spin particles and measure the spin vector in a different direction, retaining correlated statistics, which wouldn't be there if there was no connection between the particles.

Re:again with the assumptions. (1)

sexconker (1179573) | about a month ago | (#46305823)

Not quite. Entangled particles 21 Kilometers apart seem to communicate faster than the time light would take to cross the distance. Also, electrons in a semi-conductor often appear on the other side of the barrier before they have left the first side. As Bohr said "If you are not disturbed by quantum mechanics, than you don't really understand it."

Wrong.
Take known coin of two sides, heads and tails.
Flip the coin.
Look at the coin.
See that the coin landed heads-up.
INSTANTLY know that the coin landed tails-down.
The information of the coin landing tails down did not travel to you at a speed faster than c, it was simply derived from the known relation of heads and tails.

Entanglement is the same thing. Knowing one doesn't cause information to transfer to you form the origin of the other. The information was already with the observer, the entangled particles separated at speeds = c, and then the information was looked at.

Re:again with the assumptions. (0)

Anonymous Coward | about a month ago | (#46306449)

That is an over-simplified view that is taking a classical approach to entanglement, and it doesn't work with more complicated setups. If you have a process that produces a spin up and a spin down particle going in opposite directions, you could argue that. That is, until you start to do experiments where you measure for spin left and right particles, and get correlated statistics that change depending on what measurement researchers decide to do after the particles have been emitted.

Re:again with the assumptions. (0)

Anonymous Coward | about 2 months ago | (#46308741)

Information cannot be sent in this manner because one cannot modulate the spins...you cannot force the particle on your end to be spin down and therefore force the particle on the other end to be spin up, preventing you from sending FTL Morse code...

Re:again with the assumptions. (1)

maxwell demon (590494) | about 2 months ago | (#46310013)

Entanglement is the same thing.

Not quite. I think it is best seen by the Mermin paradox:

Three particles are brought into a special shared quantum state (termed GHZ state) and then distributed to three parties, who each can then make, on their own choice, one of two measurements on the particles, X or Y. Either measurement can result either in the value 1, or the value -1.

Now it turns out that while the individual results are completely random, whenever any two of them choose the measurement Y and the third one chooses X, the product of all three measures values are 1, every time.

Now, so far there's no problem: This could easily be explained by the original procedure producing not really the same state, but randomly different states which determine all measurement results, and which all fulfil the condition. This would be the analogue to your coin: Every actual state (heads up or tails up in the case of the coin, the set of six potential measurement results in the case of the Mermin paradox) fixes every measurement result, and all states fulfil a certain condition (the opposite sides of the coin having different symbols, the products of XYY-type measurements being 1 for the Mermin paradox), but the states are otherwise chosen by random. Due to the restriction on the states, you can predict one measurement result if you know the other(s) (for the coin, the down-facing symbol if you know the up-facing, for the Mermin paradox the third measured value of an XYY-type measurement if you know the other two).

Assuming this explanation, let's figure out what the product of measurement results should be if all three people measure X. To this end, let's label as x1 the measurement result the first person got from measuring X, y1 the result the first person would have gotten if measuring Y (which, in the above scenario, would be well-defined, just as in the case of the coin the symbol facing up is well defined even if you don't look at it), x2 the second person's result from measuring X, and so on.

Now we already know that y1*y2*x3=1, y1*x2*y3=1 and x1*y2*y3=1. If we multiply those three values together, we get x1*y1^2*x2*y2^2*x3*y3^2=1. But since the measurement results are all either 1 or -1, their squares are always 1, and thus we end up with x1*x2*x3=1. So according the above explanation, when all three people measure X, the product of their measurement results should be 1, every single time.

Now for the specific quantum state quantum mechanics predicts something different (and experiments confirm it, of course only within measurement error): When all three people measure X, the product of their measurement results is -1, every single time.

Re:again with the assumptions. (0)

Anonymous Coward | about a month ago | (#46304639)

Everything you say is true, but every experiment confirmed Newton for quite some time, too. More to the point, we know our physical theories are incomplete, even if we can accurately describe the universe on many scales.

I would probably find it deeply disturbing if some experiment showed a causality violation (or an equivalent); I hope this experiment does close this loophole.

Re:again with the assumptions. (1)

UnknownSoldier (67820) | about a month ago | (#46305063)

> And you can't have the possibility of sending messages back in time without breaking causality.

Incorrect assumption.

Your fallacy is assuming time is one-dimensional. There are two levels to time: Linear and Non-Linear. Or to put it a different but related way, you can know the past, present, and future, but not yet experienced it.

> you have assumption the assumption that causality doesn't exist and faster than light communication light communication is possible (both of which are contradicted on scales from pico-meters to billions of lightyears)

Contradicted by what exactly??

--
First (public) Contact is coming 2024
Are you ready for one answer that will spawn infinite questions?

Re:again with the assumptions. (1)

naasking (94116) | about a month ago | (#46305077)

You cannot have entanglement without interaction, you cannot have interaction between two things that lie outside of each other's light cones.

This is only true if interaction is local, which is not true in QM's configuration space. This is why hidden variables can never be ruled out without also ruling out QM as a whole.

Re:again with the assumptions. (1)

Immerman (2627577) | about a month ago | (#46305289)

Actually not quite, there's three possibilities and you can pick any two without problems.
(1) Relativity is completely accurate.
(2) Causality is inviolate aka time travel isn't possible
(3) FTL is possible
Personally I don't know that I'd bet my soul on any of them.

Re:again with the assumptions. (1)

pz (113803) | about 2 months ago | (#46308693)

You cannot have entanglement without interaction, you cannot have interaction between two things that lie outside of each other's light cones.

My extremely fuzzy understanding from freshman physics is that the universe is thought to have undergone an expansion early on that was, indeed, faster than light. That post-big-bang period was called "inflation", an idea Dr. Alan Guth came up with (and he happened to be my freshman physics lecturer). So it is possible that two systems that became entangled prior to inflation are now outside each other's light cones.

Re:again with the assumptions. (1)

Jason Goatcher (3498937) | about 2 months ago | (#46309931)

What about wormholes? Maybe there are dimensions where you can travel at below light speed and get there before light traveling in normal space makes the same trip the long way.

Re:again with the assumptions. (0)

Anonymous Coward | about 2 months ago | (#46312987)

Dimensions are not something that you can travel through, if you're not already doing so. Wormholes are the solution to an equation, and if they exist (which is not likely), [a] that would probably still result in a causality violation, or an apparent one, and [b] traversable wormholes are thought to require substances with negative mass.

I'm sorry you want Star Trek to be real. It seems to be impairing your thinking parts. You should read more Einstein, definitely if you're going to comment here on physics articles, and you should keep in mind, FTL = causality violation = bad.

I believe this is incorrect (0)

Anonymous Coward | about 2 months ago | (#46313735)

There have been several studies that have shown quantum entanglement operating at distances that exceed the speed of light.

I have yet to hear of any coherent explanation of how entanglement does this, exactly. "Because Bohr" doesn't do it for me.

Re:again with the assumptions. (1)

gzuckier (1155781) | about 2 months ago | (#46314167)

The catch being that the scoring of whether there is interaction is done in your brain, which is halfway between the two events, and certainly small enough to allow for interactions between the perception of the one event and the perception of the other event.
that would be one tricky universe though.

Re:again with the assumptions. (2)

BlueKitties (1541613) | about a month ago | (#46304315)

All experimental evidence suggests that the transfer of information faster than the speed of light in a vacuum is impossible. Scientists understand full well that there is always a possibility some new discovery could upend even the most fundamental view of the universe, but until evidence to suggest otherwise comes along, scientists can only work with the experimental data they have -- and so far, all of that suggests FTL transfer of information is impossible.

Therefore, drawing from the incredible amount of experimental data, it is reasonable to conclude that such stars could not have conspired with phenomenon on Earth, since the information would need to have left Earth, reached the star, then returned. The universe simply isn't old enough for such a round trip to have happened. If the max speed you can travel is 1,000 miles in an hour, and the universe is one hour old, then it is impossible to make a round trip to a destination 1,000 miles away. Therefore, if someone arrives from that destination, we know it is impossible for them to have conspired with someone from where you are at, since such a round trip would have taken at least two hours, and the universe is only one hour old.

Re:again with the assumptions. (0)

Anonymous Coward | about a month ago | (#46304373)

What the fuck is wrong with you? Have you not ever seen Star Trek TNG? This is settled science.

Re:again with the assumptions. (0)

Anonymous Coward | about a month ago | (#46304467)

"All experimental evidence suggests that the transfer of information faster than the speed of light in a vacuum is impossible."

Not true, examples of experimental and observational evidence to the contrary:

http://en.wikipedia.org/wiki/Relativistic_beaming
  - http://www.fourmilab.ch/cship/aberration.html

http://en.wikipedia.org/wiki/Speed_of_gravity
  - http://en.wikipedia.org/wiki/Speed_of_gravity

"In November 2013, Y. Zhu announced that he observed the speed of gravitational force, calculating the variations of the orbit of the geosynchronous satellites perturbed by the Sun. It is shown that the gravitational force of the Sun acting on the satellite is from the present position of the Sun. It indicates that the speed of gravitational force is much larger than the speed of light in a vacuum. From this observation and the recent experiments, the structure of the fields of a moving source (a body or a charge) is studied. A method to measure the speed of gravitational force in laboratory and a line to indirectly test the wavelengths of gravitational waves are presented."

Re:again with the assumptions. (0)

Anonymous Coward | about a month ago | (#46304647)

http://arxiv.org/abs/1108.3761

Re:again with the assumptions. (-1, Flamebait)

BlueKitties (1541613) | about a month ago | (#46305303)

I said faster than light transfer of information. Learn your damn science before you run your mouth.

Re:again with the assumptions. (0)

Anonymous Coward | about a month ago | (#46305551)

One could argue that the propagation of gravity reveals information about the mass in question. Apply some simple thought before you run your mouth.

Re:again with the assumptions. (1)

BlueKitties (1541613) | about 2 months ago | (#46308867)

Classical information, anonymous moron. You can't send something between two points on Minkowski Space along a geodesic that's undefined. Now go Google what I just said because it's pretty clear which of us has actually studied modern physics.

Re:again with the assumptions. (1)

maxwell demon (590494) | about 2 months ago | (#46310051)

One could argue that the propagation of gravity reveals information about the mass in question.

Yes. And gravity propagates with the speed of light. If some alien would manage to kick the sun out of the solar system, the earth would continue to follow its orbit for another 8 minutes. Only then would it feel the changed movement of the sun (at the same time you'd also see that the sun suddenly starts to move) and change its orbit accordingly.

Re:again with the assumptions. (1)

Immerman (2627577) | about a month ago | (#46305369)

Actually it sounds like the "speed of gravity thing" is really only an issue if you are assuming "graviton-based" gravity (yeah, I'm disappointed too). As I understand it if you assume a spatial-geometry interpretation of relativity with frame dragging (both of which we have a great deal of evidence for) then you would absolutely expect gravity to appear instantaneous within the frame. Basically it's not just the sun that's hurtling through the cosmos, the gravitationally distorted space around it is doing so as well.

Re:again with the assumptions. (0)

Anonymous Coward | about a month ago | (#46305637)

Your "graviton-based" gravity and gravity waves are both hypothetical and are not necessarily mutually exclusive.

Re:again with the assumptions. (1)

Immerman (2627577) | about a month ago | (#46306207)

Well, gravity waves are thus far undetected, but we have found evidence of binary stars losing angular momentum consistent with that predicted by gravity waves propagating at light speed (a different propagation speed would change the rate of energy loss). The lack of detection is actually quite puzzling since according to current theory there are several known binaries that should be emitting waves detectable with current equipment.

But gravity waves are actually a slightly separate issue - what I'm describing is more like the sun's gravity-well being "glued on" so that the whole thing travels with it's source, rather than trailing along behind it as happens with the light. Basically the rules obeyed by the spacetime matrix itself appear to be slightly different than those obeyed by the matter and energy passing through it.

Re:again with the assumptions. (1)

maxwell demon (590494) | about 2 months ago | (#46310099)

It's independent of whether you describe it graviton based or geometry-based. Indeed, the very same apparent problem also occurs in electrodynamics:

Assume you've got a charged particle orbiting a much heavier particle of opposite charge, and let's assume we can neglect the back-action of the radiation that orbiting particle inevitably emits. The orbiting particle feels an electrostatic force towards the central particle it orbits (which, due to its much larger mass, essentially is at rest).

Now look at the very same system in a frame of reference where the whole thing is moving perpendicular to the orbital plane. Now you would naively say that the electron should orbit a point slightly behind the central charge (because — and that has been experimentally verified — the electromagnetic field also propagates just with the speed of light, and until the field has reached the orbiting particle, the central particle has already moved on). However if you actually calculate the electric field, you'll find it points exactly to the point where the charge actually is — or more exactly, at the place at which the charge would have been predicted to be at the time when the current position of the orbiting particle could be reached with light speed if one assumed that the central particle continued to go with its current speed unchanged. That is, if the speed of the central charge changed afterwards (that is, the central charge was accelerated in the mean time), the orbiting particle will still orbit the point where the central charge would have been until the information of the change (the radiation from the accelerated central charge) arrives.

Re:again with the assumptions. (1)

amRadioHed (463061) | about a month ago | (#46305631)

If the scientists free will in choosing the settings of the detectors can't be trusted, how can their free will in choosing the quasars that will choose the settings of the detectors be trusted?

Re:again with the assumptions. (1)

BlueKitties (1541613) | about a month ago | (#46305967)

Because there cannot be casual information communication between a star of that distance and something on the Earth. In otherwords, there cannot be conspiracy between two things which are physically incapable of communication.

Re:again with the assumptions. (1)

amRadioHed (463061) | about a month ago | (#46307207)

Right, but the scientists decision to use a certain set of quasars could be influenced just as much as their decision to set the experiments parameters a certain way could be.

Re:again with the assumptions. (2)

BlueKitties (1541613) | about a month ago | (#46307525)

But the conspiring forces can't know what the quasars are sending off! That's the point. Nothing is capable of containing information pertaining to what the quasars have sent, because it's impossible to have made a round trip to find out ahead of time. Therefore, even if the forces can influence the scientist's choice of quasar, the mysterious force still has no idea which quasar will say what, so it can't rig the experiment.

As an analogy, imagine there are three settings: A, B, and C. The mysterious force wants to rig the experiment by forcing the scientist to select setting B. The scientist, to get around this, allows three quasars to select a setting. One of the quasars will pick A, one B, and one will select C. The scientist will then pick one of the quasars to set the settings. The mysterious force can choose which quasar the scientist will pick, but the mysterious force doesn't know which quasar will send which setting, therefore it can't force the scientist to pick B.

Re:again with the assumptions. (0)

Anonymous Coward | about a month ago | (#46306381)

Any pair of quasars sufficiently far away is OK here.

Re:again with the assumptions. (0)

Anonymous Coward | about a month ago | (#46304469)

This also assumes that the universe's true topology is the one that we see as descended apes. There are other topologies proposed by theoretical physicists which are actually more consistent with experimental data that would be compatible with our view but also would likely impact the formulation of entanglement. Whether these two quasars are chosen within a slice of that universe that would or would not have an impact on entanglement effects is probably something we don't know yet (oh, the horror of expressing "we don't know").

Re:again with the assumptions. (2)

clovis (4684) | about a month ago | (#46304531)

Turns out that if I had read the pdf to the end, I would have seen that they discussed the alternate expected outcome's implications in detail.

Re:again with the assumptions. (0)

iggymanz (596061) | about a month ago | (#46304729)

think about the electric fields (other fields exist, just as example) between all particles, they have always existed, for 13.8 billion years. photons are just vibrations in that field. so everything was and continues to be entangled

Slashdot future has been sending posts... (1)

Anonymous Coward | about a month ago | (#46304123)

...back into the past to warn us that the Beta is a bad idea!

Why won't Dice listen?

Build a time machine (0)

Anonymous Coward | about a month ago | (#46304185)

Just build a time machine and stop the particles in the past from conspiring with future events.

custom made (in our own image) flying monkeys (-1)

Anonymous Coward | about a month ago | (#46304217)

with lasers in their hats... keeps both the ordinary citizens & the troops on their toes. since the crown royal dna composting accident at the lhc we don't even know if the monkeys are not gargoylian in origin? still no hymens... yet

mynuts won; wizard of odd co-option infraction (-1)

Anonymous Coward | about a month ago | (#46304251)

will all the guys named bambi please raise your mouses,,, or just wave please. can you see us {;^)-)-/?

I thought (0)

Anonymous Coward | about a month ago | (#46304267)

this was going to be about aliasing and temperature gradients in voltage references. This I am comfortable with. This story sounds like how many angels can dance on the head of a pin.

Partial Free Will (1)

rdelsambuco (552369) | about a month ago | (#46304299)

What is it?

Re:Partial Free Will (0)

Anonymous Coward | about a month ago | (#46304525)

It's like when you find yourself at a quality coffee shop. You're already in the line and don't remember even entering the building. You see a menu and start considering your options. At no time does "exit the line and save your money" ever seem to be an option. After you have your 8-syllabel caffeinated beverage, you glance at your empty wallet and wonder "did I really need to spend my last remaining cash on coffee?", but you never really had a choice once that smell hit you as you were walking by.

Misread the title (0)

Anonymous Coward | about a month ago | (#46304321)

Misread the title and thought it was another NSA piece - "Make sure our lab equipment isn't tracking us".

Superdeterminism (5, Insightful)

Warbothong (905464) | about a month ago | (#46304357)

While interesting, it doesn't solve the most glaring assumption of Bell's inequality which is that the Universe is non-deterministic.

It's perfectly plausible that the Universe is deterministic, and hence the behaviour of the particles *and the experimenters* is pre-determined, ie. there is no choice in which measurement to take. Taking the determinism of the observers into account tends to be called "superdeterminism", and is necessarily a global property: either the whole Universe is superdeterministic, or nothing is deterministic. Bell's inequalities demonstrate this, since they cannot be explained by a *local* deterministic model, ie. a model which only involves properties of the particles (known as 'local hidden variables').

Note that superdeterminism doesn't necessarily rule out 'free will'. Personally I find the most elegant explanation of free will to be irreducibility: an irreducible process has no 'shortcuts'; the only way to predict its result is to run the process from start to finish. If, say, my mind is a deterministic but irreducible process, then a powerful-enough computer could predict my decisions exactly. However, I can still be said to have 'free will' because the computer can't take any shortcuts in its calculations: the only way it can predict my decisions is to run a perfect simulation of me and see what decisions that simulation makes, but in that case it's still (a perfect simulation of) 'me' making the decisions.

Re:Superdeterminism (1)

Progman3K (515744) | about a month ago | (#46304575)

I really like that, man.
I'm not peer-reviewed, so it doesn't matter, but I like your idea

Re:Superdeterminism (1)

Warbothong (905464) | about a month ago | (#46304987)

I really like that, man.
I'm not peer-reviewed, so it doesn't matter, but I like your idea

I didn't come up with it BTW ;)

Superdeterminism is a widely-known term in Physics, eg. see http://en.wikipedia.org/wiki/S... [wikipedia.org]
Irreducibility isn't as common, and it seems to go under various different names ("irreducibility" is the term used by Wolfram, eg. http://en.wikipedia.org/wiki/C... [wikipedia.org] ) and it seems to get 'discovered' over and over, eg. this ./ article from last year http://science.slashdot.org/st... [slashdot.org]

Re:Superdeterminism (1)

Progman3K (515744) | about a month ago | (#46307445)

Thanks! So that would mean that it is more likely that our universe is a simulation, right? Determinism would sort of imply it, since it can't play out any differently.

The way I've thought of it would be that it is theorized our universe is inside a black-hole; all space and time perceived is an illusion because it is all happening at the same time, in the singularity, making non-locality trivial to implement. I suppose the flaw is that you need multiple dimensions at right-angles to it to make sense of it...

Re:Superdeterminism (4, Interesting)

jfengel (409917) | about a month ago | (#46305047)

Yeah, superdeterminism was my first thought in reading this. It sounds like they're pushing any superdeterminism all the way back to the time of inflation, but since that's exactly what superdeterminism would predict, I don't see that they've contradicted anything.

It's intellectually unsatisfying to think that superdeterminism could relate to something as supremely complicated as a scientific apparatus: the whole state two measuring apparatuses conspires to yield opposite results on particles that were, up to that instant, completely identical, without any communication. But I think it makes more sense than trying to impose some outside "free will" force that also makes itself visible only on the most carefully isolated particle experiments yet also just happens to manifest as something we see numerous orders of magnitude larger as "what we think", despite layers of purely chemical interactions in between.

We're still obligated to explain the larger-scale version of "free will", in that the phenomenon that we believe it exists is real, and I think your way of looking at it is good as any. And superdeterminism doesn't contradict that.

Superdeterminism still doesn't satisfy, but I suspect that "satisfaction" is a purely human property. The equations yield the right answers, and that's all you get. Like classical dynamics, free will is an idea that we're going to keep expecting to see, even though we'll always get out unsatisfying answers when we try to explain corner cases.

Re:Superdeterminism (1)

SoftwareArtist (1472499) | about a month ago | (#46307511)

It's intellectually unsatisfying to think that superdeterminism could relate to something as supremely complicated as a scientific apparatus:

Why do you say that? If the whole universe is deterministic, then of course every part is deterministic. A scientific apparatus is incredibly simple compared to the universe as a whole.

Perhaps what you mean is that you want to know what mechanism creates the appearance of randomness/entanglement/free-will in a fully deterministic universe? Why does it appear that your actions have an influence on distant events, and that influence takes the form of a certain type of correlations between observables? It would be unsatisfying to declare, "It just happens, and there's no reason for it. It was just predestined that you would make the choice consistent with those correlations - for no reason." That would be incredibly improbable. Clearly there must be a mechanism.

Fortunately, we have very good ideas about what that mechanism might be. There's increasingly strong evidence for retrocausality and/or non-locality, either of which provides a straightforward mechanism to produce those correlations. And, not surprisingly, either one of them would be very hard to reconcile with a non-deterministic universe.

Re:Superdeterminism (1)

jfengel (409917) | about 2 months ago | (#46308401)

The problem is that it's hard for me to conceive how, early on in the universe, the particles that would eventually make up my measuring apparatus and the particles that eventually make up your apparatus went their separate ways, in such a fashion that at a particular time they'd interact with two identical entangled particles and give opposite results. It's such a complex thing to achieve such a simple result.

Not that there's anything wrong with that, if that's where the universe happens to lead us. It is what it is. I don't have much interest in "free will" and don't see what all the fuss is about; it's pretty obviously a rump explanation of a macro phenomenon with no real manifestation as a separate entity.

Explanations involving retro-causality or non-locality are probably equally good ways of looking at the same phenomenon. Either one would have to be highly restrictive versions, because special relativity sets some constraints on it that for aesthetic reasons I suspect are insurmountable. That is, time travel feels like wishful thinking, and I suspect that retrocausality/non-locality would not enable it. But that's just a guess.

Re:Superdeterminism (0)

Anonymous Coward | about a month ago | (#46305221)

I believe this is also known as "soft determinism".

Re:Superdeterminism (1)

Khashishi (775369) | about a month ago | (#46305353)

But, wouldn't a rock have free will under that definition? Well, it depends on what you consider a decision to be. Everything is irreducible to some extent. You can get a pretty good approximation of the behavior of a rock by considering a idealized spherical mass, but to get more precise, you need to add more detail. For a perfect account of the behavior, you need the full quantum state of the system.

Non-contributing fistbump (0)

Anonymous Coward | about a month ago | (#46306331)

While I don't actively search for it, I pretty much never (sadly) see anyone who shares my view on free will. So yay. Also I had never heard the term irreducibility before. Thanks!

Re:Superdeterminism (1)

Eric Damron (553630) | about a month ago | (#46306667)

"Note that superdeterminism doesn't necessarily rule out 'free will'."

I guess I don't understand how the example that you gave following that statement supports the idea of "free will." For me the more interesting question is: "What does awareness mean in a deterministic world?"

Are we just observers riding the deterministic "roller coaster?"

What about Many Worlds? (1)

Agent0013 (828350) | about a month ago | (#46307149)

Perhaps the Universe is deterministic and the results are pre-determined. Or what if the many worlds theory is correct and any worlds where the results of the experiment don't square up are the worlds that cease to exist. We would always find ourselves in one of the branching worlds where the results of the quantum experiments match in the same way as if the detectors were tuned for those results.

Question to experts in quantum physics (1)

n01 (693310) | about 2 months ago | (#46308179)

Does the following make any sense?

My thinking was that if two far-away detectors measure an entangled pair of photons (e.g.), each detector will measure both possible results (e.g. up *and* down). Each detector and thereby their environment becomes entangled with that photon. So each detector and it's environment starts a new branch in their respective many-worlds reality. (One side of the branch for “up” and one branch for “down”).

When you later compare the measurements of the detectors, you will find the measurements pair up (for example they are opposite). In the classical interpretation this could be thought of as a “spooky action at a distance” (instantaneous synchronization). But in the many-worlds interpretation only the worlds where the two separate measurements pair up would survive (the worlds where there is no match would cease to exist, as you put it). This would require no instantaneous synchronization, but would appear as such at the moment when the station that is comparing the measurements is becoming entangled with both detectors, e.g. by receiving the measurement outcome information from both detectors. The four “realities” (e.g up-up, up-down, down-up, down-down) meeting at that moment would be reduced to two “realities”, by merging pairs of “compatible realities” (only up-down and down-up “survive”).

INAQP (I’m not a quantum physicist) so I hope all of this makes sense. And I guess I haven’t added much to the parent’s point except adding a (hopefully valid) example.

If any expert reads this, I would love to know where I can read more about these ideas. There would certainly be a term for this already.

I only wonder why this possibility isn’t discussed more often, I seems such an easy way out of the paradox.

What? (1)

Impy the Impiuos Imp (442658) | about a month ago | (#46304403)

> "implies that a physicist running the experiment does not have complete free will"

There is no such thing as free will in the old philosophical sense. There is just determinism with (potentially) true quantum randomness. The latter could be based on a deeper determinism, but that is exactly the kind of "reality" Einstein didn't want to gove up on -- real things out there with real, measurable properties. Quantum mechanics based on an even deeper determinism would doubly violate this principle by shoving the "real things" not one but two levels deeper from Einstein's real objects like particles.

Re:What? (1)

phantomfive (622387) | about a month ago | (#46304691)

Heh......

"The wise old philosopher finally proved that there was no such thing as free will. What did he do next? Whatever he wanted."

Re:What? (2)

Remus Shepherd (32833) | about a month ago | (#46304711)

You are neglecting the possibility of true dualism -- that we have a soul. If a portion of our decisions comes from an extra-universal source that does not follow the deterministic rules of the universe, that would provide us with true free will. Sadly, such a thing may be innately non-provable.

Re:What? (1)

Khashishi (775369) | about a month ago | (#46305415)

That would be considered a "hidden variable" theory. For this soul theory to be able to explain quantum mechanics, the soul must have some faster than light communication.

News will report it as proof of Free Will (3, Interesting)

Remus Shepherd (32833) | about a month ago | (#46304409)

A year from now you should expect to hear about this research again, but it will be delivered as a dramatic result: "Scientists have proven Free Will exists!", or "Scientists have disproven Free Will!" The experiment won't actually do this, but that's how the press will report it.

The thought that some hidden variable may affect not only both sides of the universe but our own minds is frightening. It would really shake things up. So I expect that QM and 'free will' will come out triumphant in this test. Whether it's an actual assessment of Free Will or not will be the interesting argument afterward.

Re:News will report it as proof of Free Will (2)

TheCarp (96830) | about a month ago | (#46304911)

I am kind of hoping they will close the loophole and find the equality is still violated. If so, then i actually expect the headline "Do far away stars disprove quantum mechanics?"

Re:News will report it as proof of Free Will (2)

Immerman (2627577) | about a month ago | (#46305445)

As it is classical physics had already ruled out the possibility of free will centuries ago, and QM only inserted a bunch of dice-rolling that could give the illusion of it. For free will to actually exist we must assume some sort of non-physical "soul" that can manipulate the outcome of the dice.

Theoretically at least we could monitor every quantum effect that influences the brain and look for statistical anomalies, but even if no anomalies were found that wouldn't rule out free will - rolling 2,5,3 is statistically equivalent to rolling 3,2,5, but the effect on the game can be very different.

Also, being scary and disruptive is hardly an argument against the accuracy of a theory - if it were then nuclear physics wouldn't exist.

Re:News will report it as proof of Free Will (1)

lucien86 (917502) | about 2 months ago | (#46314551)

As it is classical physics had already ruled out the possibility of free will centuries ago, and QM only inserted a bunch of dice-rolling that could give the illusion of it. For free will to actually exist we must assume some sort of non-physical "soul" that can manipulate the outcome of the dice.

Have to disagree with you there, by the definition that I know that free will is a Turing Machine classical physics certainly doesn't stop it or rule it out.. It is only General Relativity with its fixed past and potentially fixed future that really disallows free will, but then if General Relativity is correct the universe basically doesn't exist anyway so the question is pretty moot. :)

Re:News will report it as proof of Free Will (1)

Immerman (2627577) | about 2 months ago | (#46314647)

I have never heard such a claim (Turing), and I would contest it strenuously. A Turing machine is a deterministic device - with a given input there is exactly one outcome possible. You may not be able to say for certain that any given input will eventually terminate beforehand, but give a billion machines the same input and they will all proceed in the exact same fashion, with no possibility of expressing free will.

And operating under classical physics the entire universe is deterministic - if you could somehow know everything about every particle and photon in the universe at this instant, and the laws governing their behavior, you could theoretically predict what your billion-times-great grandson will have for breakfast on his seven birthday.

I have never heard anything to suggest that General Relativity implies a fixed past, nor anything about the universe "not existing", I think you may have misunderstood something. Or maybe are reading journals far more esoteric than my chosen fare. In any event without a fixed past things get somewhat "squishier", but presuming it is something in the future that changes the past, under classical physics that event could also be predicted today, along with the outcome of the changes to the past. In a clockwork universe the only unknowns are due to ignorance.

Re:News will report it as proof of Free Will (1)

lucien86 (917502) | about 2 months ago | (#46315841)

Oh dear! The way we operate Turing machines they mostly do behave as deterministic devices but just go and try injecting a little noise into the system, even the tiniest amounts - they certainly do not behave as deterministic devices then. In fact if you try to calculate the size of a computers potential state space it is so large that it is effectively infinite (maybe ~10^10^10^10^10) yet the actual physical state at any one time will only be a few points within that space and this ratio means that computers are theoretically potentially among the most chaotic least predictable things in the universe.

Ok the simple truth is that if you could observe free will completely then it would be fully deterministic - just as a computer would be fully deterministic if you could know and understand every atomic part of its functionality and operation. In practice neither is true. Computers do mostly behave deterministically because every part of the design is constrained by strict rules - but even so computers crash or make mistakes every day. And here is the crucial point, in any sufficiently complex system there are always 'bugs' or errors or noise - and these are a side effect that indicates a limit to absolute determinism.

Any sufficiently complex system is not completely deterministic and this includes the brain and mind - the argument that the classical universe is not fully deterministic is merely an extension of this argument. If an observer existed with infinite sensory power and memory and intelligence then it could probably mark the classical universe as completely fully deterministic - however such an observer is itself impossible. The classical argument fails precisely because it fails to look at the nature of the required observer.

As for General Relativity I only used the word 'implies'. General Relativity only implies a fixed past and future because the dimension of time is described as physically real and this means that the past and future have an actual physical existence. (4D space time) This is only one interpretation and even then the past and future can only be reached by crossing an FTL barrier.

As for my sources, New Scientist (from many years ago and more recently), Isaac Asimov's science extrapolation books, standard physics textbooks and places like Wikipedia. As for AI/computing, I have been interested in the field for almost 30 years and am pretty widely read. A useful starting point is Roger Penrose's "The Emperor's New Mind." or lookup 'Artificial Consciousness' in Wikipedia.

Re:News will report it as proof of Free Will (0)

Anonymous Coward | about 2 months ago | (#46316165)

I have to concur with the other poster, and have never seen free will defined that way, usually pushed as some opposite of determinism. A Turing machine with noise is not a Turing machine, but one of a couple different machines depending on exactly what type of noise you are talking about. But a mind that is a machine that behaves deterministically, even if that requires an impractical level of measurement, is philosophically considered not having free will. This is why the debate got more interesting with quantum mechanics, (although in part because a large portion of philosophy studiers don't understand or put time into properly learning QM), because it offers a description of the world where the amount of measurement needed for determinism is not impractical, but impossible.

Forced Blindness (1, Offtopic)

Jim Sadler (3430529) | about a month ago | (#46304689)

For quite a few people with either religious or unusual beliefs there is a belief that the nature of reality or actuality can not be penetrated as a designed law installed by a creator. If it is simply an advanced race and we are living in their simulated universe or whether if is God that intends for us to live within a perpetual mystery the end result is the same. Humanity will never be allowed to understand the nature of things. There is also some belief that only after death are we allowed understanding.

Re:Forced Blindness (1)

lucien86 (917502) | about 2 months ago | (#46314639)

This is why the scientific study of the 'psychic' is probably the most controversial and 'dangerous' area that science has ever touched. Imagine if science had discovered that the psychic was real then used reductionism to reduce it all to first principles and logic and ultimately physics. It would literally be the end for religion, the death of mysticism and a direct confrontation against the nature of 'God'. Even worse imagine that 'God' becomes a technology - created and manipulated in the lab, used to build machines, an everyday commodity. Arthur C Clark's phrase "Any sufficiently advanced technology becomes indistinguishable from magic." becomes a cry to war for both sides, for the side of science and rationality, and for the religious and traditionalists- especially for fundamentalist religion.

An interesting conspiracy theory is that a group of scientists discovered the whole thing in the 1950's but were then banned from publishing it because it was so confrontational..

Free Will is an Illusion (1)

Eric Damron (553630) | about a month ago | (#46306537)

"a scenario that, however far-fetched, implies that a physicist running the experiment does not have complete free will in choosing each detectorâ(TM)s setting."

Of course the physicist doesn't have free will. No one has free will. If the universe is controlled by natural laws everything that has happened or ever will happen must be preordained. Every synapse that has ever fired in our brains is just an electrochemical event caused by a long chain of other events that can be traced back to the big bang.

Re:Free Will is an Illusion (1)

miroku000 (2791465) | about 2 months ago | (#46309437)

>Of course the physicist doesn't have free will. No one has free will. If the universe is controlled by natural laws everything that has happened or ever will happen must be preordained. Every synapse that has ever fired in our brains is just an electrochemical event caused by a long chain of other events that can be traced back to the big bang. That is assuming that natural laws actually are complete and consistent. But why would this be true of natural law, when it is not even true in mathematics? http://en.wikipedia.org/wiki/G... [wikipedia.org]

Anthropic Principle? (1)

Tablizer (95088) | about a month ago | (#46306851)

Is this perhaps a form of Anthropic Principle? Universe instances where Experiment X is a deadly no-no get annihilated such that nobody is around to witness Experiment X take place to completion.

Considering how many hair-raising Cold War near-misses we've had, I wonder if AP is not involved. Between the Cold War and LHC, we may be running out of universe instances :-)

Its a Simulation Anyway (0)

Anonymous Coward | about a month ago | (#46307075)

So none of this is surprising. The programmer's free will is to blame.

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