Quantum ‘spookiness’ passes toughest test yetThis is just the latest of the Bell test experiments. These were very exciting about 50 years ago, because they had the potential to disprove quantum mechanics. All the tests, including this one, have confirmed the quantum mechanics of 1930.
Experiment plugs loopholes in previous demonstrations of 'action at a distance', against Einstein's objections — and could make data encryption safer.
It’s a bad day both for Albert Einstein and for hackers. The most rigorous test of quantum theory ever carried out has confirmed that the ‘spooky action at a distance’ that the German physicist famously hated — in which manipulating one object instantaneously seems to affect another, far away one — is an inherent part of the quantum world.
The experiment, performed in the Netherlands, could be the final nail in the coffin for models of the atomic world that are more intuitive than standard quantum mechanics, say some physicists. It could also enable quantum engineers to develop a new suite of ultrasecure cryptographic devices.
“From a fundamental point of view, this is truly history-making,” says Nicolas Gisin, a quantum physicist at the University of Geneva in Switzerland.
This does appear to be an improved experiment, because previous ones had to make some mild assumptions about undetected photons. This cleverly uses electrons that can nearly always be detected.
However, it does not demonstrate action-at-a-distance, and it will not make data encryption any safer. It just gives more evidence against the hidden variable theories that everyone rejected in 1930.
These experiments are often suggested as candidates for the Nobel Prize in Physics. Maybe so, as these are nontrivial tests of good physics theories. But really, prizes for the theory were given in 1932 and 1933.
Sweden cannot give prizes for string theory, unified field theory, quantum gravity, black hole information, multiverse, supersymmetry, quantum computers, or any of the other topics that seem to preoccupy our finest Physics minds, because none of those have any experimental validation.
Update: Scott Aaronson describes this work, and concludes:
At a more fundamental level, will this new experiment finally convince everyone that local realism is dead, and that quantum mechanics might indeed be the operating system of reality? Alas, I predict that those who confidently predicted that a loophole-free Bell test could never be done, will simply find some new way to wiggle out, without admitting the slightest problem for their previous view. This prediction, you might say, is based on a different kind of realism.By "local realism", what he really means is Local hidden variable theory, a foolish effort to disprove quantum mechanics.
Yes, I am convinced that local hidden variable theory is dead. It has been dead since 1930. This experiment is just another nail in the coffin.
I just don't agree with this use of the term "local realism". Quantum mechanics is the local realistic theory, not hidden variable theory.
Update: Several comments now criticize Aaronson's use of the term "local realism" as wrong as misleading. He insists on using it:
As I use the term, “local realism” is not a “physics definition,” it’s a math definition. And Bell’s theorem is not a “physics theorem” (whatever that means), it’s a math theorem that’s been proved and will stay proved until the end of time. If you want to argue about the theorem’s relevance to physics, you can do that, but you don’t get to negotiate the definition of “local realism,” because it’s now part of math.He doubles down here. By a math term, he means associated with some stupid disproved mathematical hidden variable model. I think that he likes the term because it sounds profound to say that quantum mechanics has been proved contrary to local realism.