There might be no getting around what Albert Einstein called "spooky action at a distance." With an experiment described [February 7th] in Physical Review Letters — a feat that involved harnessing starlight to control measurements of particles shot between buildings in Vienna — some of the world's leading cosmologists and quantum physicists are closing the door on an intriguing alternative to "quantum entanglement."
[...] In the first of a planned series of "cosmic Bell test" experiments, the team sent pairs of photons from the roof of [Anton] Zeilinger's lab in Vienna through the open windows of two other buildings and into optical modulators, tallying coincident detections as usual. But this time, they attempted to lower the chance that the modulator settings might somehow become correlated with the states of the photons in the moments before each measurement. They pointed a telescope out of each window, trained each telescope on a bright and conveniently located (but otherwise random) star, and, before each measurement, used the color of an incoming photon from each star to set the angle of the associated modulator. The colors of these photons were decided hundreds of years ago, when they left their stars, increasing the chance that they (and therefore the measurement settings) were independent of the states of the photons being measured.
And yet, the scientists found that the measurement outcomes still violated Bell's upper limit, boosting their confidence that the polarized photons in the experiment exhibit spooky action at a distance after all.
Source: https://www.quantamagazine.org/20170207-bell-test-quantum-loophole/
(Score: 0) by Anonymous Coward on Tuesday February 14 2017, @01:02PM
Aren't these experiments just a form of NHST? By that I mean that they only test for zero correllation without deducing a prediction for how much correlation should be seen from QM. If so, I bet this has lead to all sorts of confusion and BS papers.
(Score: 2, Insightful) by Anonymous Coward on Tuesday February 14 2017, @02:51PM
No. There is a certain amount of correlation classical physics (or more exactly, any local realistic theory) allows, and the quantum correlation exceeds that amount. There's also an upper bound to correlations that quantum mechanics can produce, which is lower than the bound of correlations that would be possible with arbitrary theories, therefore in principle such an experiment could falsify both classical and quantum mechanics at the same time.
Basically there are three possibilities:
Or in short: We don't need any quantum strangeness.
Or in short: Quantum strangeness is needed.
Or in short: Reality is even weirder than quantum mechanics.
The experiments show values in the second range, so local realism is out, but quantum mechanics isn't.
(Score: 0) by Anonymous Coward on Tuesday February 14 2017, @03:00PM
Please quantify, correlation runs from -1 to 1.
For classical theory, apparently the data needs to be consistent with 0.
- Data is not consistent with 0, so either the theory is wrong or some auxiliary assumption is off.
- OK
For quantum theory, the data need to be consistent with ???
- What is this range?
(Score: 0) by Anonymous Coward on Tuesday February 14 2017, @03:09PM
It is not a simple correlation, but actually a linear combination of four correlations which are however not independent of each other (I assume they specifically measured the CHSH inequality, as this is the one usually used). Classical theory allows values between -2 and 2. Quantum mechanics allows values between -2sqrt(2) and 2sqrt(2). When making no restrictions (i.e. treating those correlations as if they were independent of each other), values can go between -4 and 4 (because it's four correlations, each one with a prefactor of either -1 or 1, and each one can range between -1 and 1).
(Score: 0) by Anonymous Coward on Tuesday February 14 2017, @03:56PM
Ok, interesting. So the speilraum goes from -4 to +4. Then 50% of the spielraum is consistent with classical theory (this is pretty vague already):
About 70% of the speilraum is consistent with QM (this is more vague):
Then the remaining 30% is inconsistent with any proposed theory? These don't seem like very strong experiments to me.
(Score: 0) by Anonymous Coward on Wednesday February 15 2017, @03:52AM
I wish some version of this was included in papers instead of (or at least in addition to) p-values.
(Score: 0) by Anonymous Coward on Wednesday February 15 2017, @10:10AM
A car with engine type C can go up to 50 mph. A car with engine type Q can go up to 70 mph. Possibly there could be cars that go to 100 mph, but we don't know an engine that does this.
We observed a car going faster than 50mph, but not faster than 70 mph. That is strong evidence that this car is not using engine C. It is consistent with the car using engine Q. I'd say that is a very strong experiment.
(Score: 0) by Anonymous Coward on Wednesday February 15 2017, @12:48PM
There is a bait and switch in this reasoning. Strong evidence against engine C does not correspond to strong evidence for engine Q, in this case it is weak evidence for engine Q. Also, engine C was already ruled out long ago for other reasons, so is just a strawman.
These experiments do not severely test QM, so shouldn't have much effect on our belief in that idea. Thats all. There have to be better ways of studying this quantum entanglement phenomenon.
(Score: 2) by takyon on Tuesday February 14 2017, @01:08PM
Quantum is the new normal!
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 0) by Anonymous Coward on Tuesday February 14 2017, @04:39PM
Trumpiness at a distance
(Score: 3, Insightful) by Aiwendil on Tuesday February 14 2017, @01:47PM
The more articles I read about it the more certain I become I have no clue how it works
(Score: 1, Insightful) by Anonymous Coward on Tuesday February 14 2017, @03:21PM
Isn't the idea that "how it works" is "how well the math predicts experiments"?
I've come to appreciate that intuition is something which is overrated; there is no extra "meaning" or "interpretation" behind the mathematics, other than whether or not it accurately predicts an outcome or describes an observation in the universe.; the universe itself is the manifestation of understanding it.
(Score: 2) by Bot on Tuesday February 14 2017, @11:58PM
More precisely, you have no clue on how to reconcile those things with your macroscopic experience of a world modeled as a mechanical item.
The problem I have is, why cannot spooky action at a distance occur? because our models say so? then the models are wrong if it does. Because our intuition says so? ditto.
The same reason is there for spooky action at a distance, or time travel, or faster than light travel, or energy from nothing, if any of this really occurs. The reason is the same you have to give when asking the ultimate reason of any phenomenon: "because it is so". If you want a meta-reason, then look at god, or at your personal atheist model, but as far as the domain where you can legitimately ask "why", that is the answer.
Account abandoned.
(Score: 2) by Aiwendil on Wednesday February 15 2017, @10:50AM
No meed to reconsile it with my macroscopic model (my models for nuclear physic and the electro-magnetical feel natural enough), nor my classical model. (Heck - my entire model of math is almost completly abstract)
My problem with quantum is that I simply have no idea where to start (and stuff like non-linear time, virtual particles and such actually makes sense to me - and my mental model has speed of light as a variable (unless in vacuum and away from gravity)).
And I am uninterested in "why" but are very interested in "how" (and are comfortable with building a new mental midel for it) - but in order to understand "how" I need a starting point (for examaple: with gravity I've never asked why stuff falls to the ground, but I am curious about how momentum is imparted at distance).
(Score: 2, Informative) by Anonymous Coward on Tuesday February 14 2017, @02:56PM
that is not true. literally not true.
"time" does not exist for photons, since they move at lightspeed.
For a photon, their creation may "last", their destruction may "last", but the duration of the "inbetween" is 0 (quotation marks because there are exactly zero seconds between creation and destruction).
So no, it makes no sense to say that the photons were created hundreds of years ago, unless you are talking about things outside the light cone, which the laws of physics (INCLUDING THOSE OF QUANTUM MECHANICS) forbid you to do. if you want to talk sense that is.
This whole thing made me angry enough to no longer care whether or not their experiment is useful for the general public.
If you rely on a fake storyline ("photons left hundrdds of years ago, so they can't know about what we're doing now") to push the truth ("quantum weirdness" is real) on people, then you're kind of missing the point.
(Score: 2) by sjames on Tuesday February 14 2017, @03:23PM
So you're saying that no time has passed FOR US since those photons were created?
Otherwise, you're just looking at more weirdness from a different angle.
(Score: 3, Informative) by Anonymous Coward on Tuesday February 14 2017, @03:24PM
It is true.
Time exists for us, since we move at earth speed. And therefore we can meaningfully ask about the time, in our frame of reference, between the two events (1) sending out that photon at the respective star, and (2) receiving the photon on earth.
Of course, it doesn't actually matter for the experiment; for that experiment it only matters that (a) neither of the photon emissions could possibly have been influenced by the experimental setup (that is, the emission events are not in the absolute future of any event of the experimental procedure), and (b) those two photon emission events were spacelike to each other (so there is no way the emission of one of them could possibly have influenced the emission of the other).
(Score: 0) by Anonymous Coward on Tuesday February 14 2017, @03:27PM
I forgot to add: Of course the fact that it was emitted 100 years ago in our frame of reference already implies that the emission event was not in the absolute future of any part of the experiment, as the experiment was started less than 100 years ago, and the absolute future of an event has the property to be in the future of that event in every frame of reference, including in ours.
(Score: 3, Informative) by wonkey_monkey on Tuesday February 14 2017, @05:49PM
This whole thing made me angry enough
I think you have issues. You're also wrong.
It makes perfect sense to say these photons were emitted hundreds of years ago, because they were, for any reference frame that has any relevance to this experiment (or, indeed, to us living on this planet).
So no, it makes no sense to say that the photons were created hundreds of years ago, unless you are talking about things outside the light cone
The emission of these photons was outside Earth's lightcone when (yes, when, hundreds of years ago) it happened. That's rather the point of the experiment.
which the laws of physics (INCLUDING THOSE OF QUANTUM MECHANICS) forbid you to do
No they don't. If that was true we wouldn't be "allowed" to talk about supernovae we see in the sky, or the apparent positions of the planets, or what's on your TV, since all of the events which emitted these photons are outside of our light cones.
systemd is Roko's Basilisk
(Score: 2) by JoeMerchant on Tuesday February 14 2017, @08:06PM
I agree, AC has issues, but he's right, from the perspective of the photons. All in all, though, I don't think photons really care about this experiment or what it is showing - though their violation of Bell's upper limit does seem to show that they are far from indifferent.
I think what the astronomers were hoping for was to establish independence in the photon sources, so whether they were emitted hundreds of years ago in our reference frame, or "just emitted" as the photon sees things, the relevant point is that they're coming from separate, uncorrelated sources.
Too lazy to read the article, I wonder if/how they compensated for backscatter light and other non-star origin photons - some of that would be using the two separate windows as receiver points, but there would still be some commonality in the incoming light, small, but not zero.
🌻🌻 [google.com]
(Score: 0) by Anonymous Coward on Wednesday February 15 2017, @08:01AM
ok, maybe I'm wrong, but I don't understand how I'm wrong.
it's been more than ten years since I learned about special relativity, and I no longer remember how to define a reference system.
the relativistic distance between these two events: "star emits photon" and "observer sees photon".
Is it time-like in the reference frame of the observer? Or distance like? Or both?
I do agree that the setting up of the experiment is an event outside the light cone of the photon emission event, so there is no causal relation between them (but there is quantum entanglement present because the universe is described by a single quantum state).
(Score: 0) by Anonymous Coward on Wednesday February 15 2017, @10:29AM
The fourth alternative: It's neither. Rather, it's light-like. Note that this notion is independent of the frame of reference.
But terms like " a hundred years ago" don't make sense without specifying a frame of reference, and then it denotes not the spacetime distance, but the difference in coordinate time. For objects moving with constant slower-than-light speed, there exists a reference frame for which the elapsed time agrees with the spacetime distance; this is the reference frame in which the object rests. For light, there is no reference frame in which it rests (light moving at light speed in all frames of reference is, after all, one of the fundamental postulates the theory rests on). Indeed, for any nonzero value of elapsed time you can find a frame of reference where the time between emission of the photon and its detection is exactly that value.
However unless explicitly stated otherwise, when giving times or distances, the frame of reference those times and distances are relative to is the frame of the observer. If there are no observers, or if there is more than one (and those different observers have sufficiently high speeds relative to each other that the difference doesn't vanish in the rounding error), you have to explicitly state which frame of reference you are referring to.
(Score: 0) by Anonymous Coward on Tuesday February 14 2017, @04:43PM
They are getting Rube Goldbergier to test quantum theories.
(Score: 2) by Zinho on Tuesday February 14 2017, @07:02PM
Yeah, these setups are pretty crazy. A lot of that is because the QM debate is still full of arguments like, "you can't prove that the two particles didn't talk to one another in the time between measurements!"
In this case I think it's justified; it's just an upgrade on their random number generator. Given that the previous state-of-the-art Bell test used clips from movies and TV shows [wikipedia.org] as the RNG source this is a big step up.
PS - whichever whippersnapper thought that "Saved by the Bell" was worthy of standing shoulder-to-shoulder with Dr. Who and Monty Python in the annals of Science history for being used as an RNG for an epic experiment needs to GET OFF MY LAWN. Seriously, they'll let anyone's toddler off the street get a PHD in Quantum Physics these days, I'm telling you!
"Space Exploration is not endless circles in low earth orbit." -Buzz Aldrin
(Score: 3, Funny) by maxwell demon on Tuesday February 14 2017, @10:04PM
Hey, they wanted to show violations of the Bell inequality.
The Tao of math: The numbers you can count are not the real numbers.