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Making Sure Our Lab Equipment Isn't Tricking Us
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)."
Don't anthropomorphize the machines. They hate that, and will go back into their past to get you!
This issue is a bit more complicated than you think.
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?
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.
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.
...back into the past to warn us that the Beta is a bad idea!
Why won't Dice listen?
Just build a time machine and stop the particles in the past from conspiring with future events.
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.
What is it?
I comment occasionally so that I can mod others -1 overrated or -1 offtopic.
Misread the title and thought it was another NSA piece - "Make sure our lab equipment isn't tracking us".
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.
> "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.
(-1: Post disagrees with my already-settled worldview) is not a valid mod option.
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.
Genocide Man -- Life is funny. Death is funnier. Mass murder can be hilarious.
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.
if this is supposed to be a new economy, how come they still want my old fashioned money?
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.
I did write a blog post about quantum mechanics and the “free will theorem” at the time.
http://stephan.sugarmotor.org/...
I think this new development isn't covering all possibilities there
http://stephan.sugarmotor.org
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!
"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.
The race isn't always to the swift... but that's the way to bet!
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 :-)
Table-ized A.I.
So none of this is surprising. The programmer's free will is to blame.
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.
-- ssoorrrryy,, dduupplleexx sswwiittcchh oonn.. -Quote found on actual fortune cookie.
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.
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. . .
Below the speed of light Special Relativity is one of the most accurate theories in physics - above the speed of light..
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.