Thread: Connection Between Quantum Non-locality and Heisenber's Uncertainty Principle.

Surprise link between weird quantum phenomena: Heisenberg uncertainty principle sets limits on Einstein's 'spooky action at a distance'

I thought Einstein was referring to Newtonian explanations (or lack there of) of gravity when he coined the term "spooky action at a distance." This was what led him to search for a physical explanation for gravity. The specific thought experiment involved the notion of a disappearing star. If a planet were orbiting a star and that star could suddenly disappear how long would it take for the orbiting planet to "feel" this. In other words does gravity act instantly at a distance or does it tike time to travel? Am I wrong? Have I misplaced that quote? Was he referring to a quantum phenomenon, and if so what would he think of modern experiments on quantum entanglement? Please explain.

If a planet were orbiting a star and the star suddenly disappeared, the gravitational force (or lack thereof) would be travelling at the speed of light. So right about the time these unfortunate aliens figured out that they were hosed, the gravitational wackiness would be occuring as well. So in reality, gravity "travels" (so to speak) at the speed of light.

Einstein, to the best of my knowledge, was partially referring to quantum entanglement when he made that quote. Quantum entanglement is a bizarre phenomenon, and Einstein was partially against it because if entanglement were shown to be true, in his mind this would undo special relativity, because information between these two entangled particles would be travelling faster than the speed of light. Well, it ultimately turns out that the nature of elementary particles is very wave-like, and so when particles interact, sometimes their wave functions can become connected. Since a wave function is a probability wave that effectively can extend great distances, these particles could almost be thought of as "still touching", and so when something happens to one particle, the other particle reacts accordingly. It's not so much that information is travelling faster than light, it is that their wave functions are still connected, so even though their may be distance between them, they are still, in a VERY complicated sense, touching one another through this wave function.

Anyone with a little more experience in quantum mechanics wanna take a swing at this one as well, just in case there is anything I missed?

First the gravity comment may or may not be true. We don't know yet whether or not there are gravitational waves, despite what Einstein's equations say. As my friend Marti Veltman told me, "GR needs to be ripped up and thrown away. As a young theorist you should start from scratch when it comes to gravity, because GR is wrong."

The deal with spooky action at a distance has to do with quantum entanglement. The results posted at the top of this thread are fascinating and I just saw them a couple days ago. Without getting into the nitty gritty of quantum mechanics, it's best to deal with it in terms of information theory. Say an electron-positron pair pop out of the vacuum. They contain no net information since you can't just create information from nothing. However, you have to conserve angular momentum right? So if one is spin up, the other has to be spin down. Let them fly to opposite ends of the universe. Now since it's quantum mechanics, each one exists in a superposition of spin up and spin down, so it doesn't actually take a definite value until you measure it...each travels through space as a superposition of both possibilities. What Einstein didn't like was 1) God doesn't play dice...so he fundamentally disagreed with this premise of superposition to begin with. But I control my particles and I didn't let God get anywhere near them (I had an army from Hell guarding them to make sure God stops with his gambling problem...you know all his friends tried to have an intervention, but he's too stubborn--he has this arrogant God complex). So I measure the electron, and let's say it turns out to be spin up. Einstein didn't like the fact that 2) instantaneously the positron becomes spin down despite the fact their at opposite ends of the universe. He thought information had to travel across the universe in order to let the other particle know the result of the measurement. Einstein's problem was that he viewed the universe in terms of rods and clocks...spacetime. Entanglement shows you that this is the wrong way to look at the universe...just because your eyes see something to be as such doesn't mean reality is best described as such. So you take a more natural view and look at the universe in terms of an information metric instead of a spacetime metric (Information Geometry vs Spacetime Geometry). Both actually obey Einstein's General Relativity equations, so fundamentally you can choose whichever is more natural to you. In spacetime they're far apart, however in information space, they're the same object--a single point. So what Einstein calls spooky action at a distance, I call spooky spacetime at a point. And this is where two schools of thought emerged. John von Neumann said "halt! Your spacetime makes no sense, let's look at things in terms of information space," while everyone else said "shut up John, we're going to pretend this doesn't happen." So quantum field theory develops and string theory develops and none of these incorporate any explanation of entanglement. However, I picked up the fight 70 years later and said, ok it's time to reformulate everything in terms of information because physicists just aren't getting it. Now physicists are reading this and don't understand information theory at all. So let me justify. You have an electron, a quark...any fermion, it has spin up or down (1 bit), and helicity left or right (1 bit), and charge (1 bit). It also has mass, which slows it down in spacetime, but in information space acts as a stochastic bit flipper on the helicity bit. So as it travels through spacetime, it keeps randomly flipping helicity. Then you have stuff like light...bosons, which have a polarization (1 bit), and maybe a mass and charge for the weak and strong bosons (log base 3)...things get kind of complicated in the bosonic picture, but it still works. Now bits are information quantities, but they're also entropy units. So what you do is place these guys on the Fisher Information Metric now, instead of the spacetime metric. In spacetime they travel along geodesics, but you don't know how they're related to each other...everything's kind of entangled. So at the quantum level, everything is spooky when you try to make sense of things in spacetime, like the double slit experiment. But on the Fisher Information Metric, they also follow geodesics, and these geodesics tell you exactly how the probabilities interact. So all of a sudden quantum mechanics makes sense and doesn't look weird, but you can't tell how stuff moves in spacetime anymore. So to understand exactly what's going on in the universe, you have to work in both representations simultaneously. This is what John Wheeler originally phrased as "It from Bit," but didn't have the information geometry to do at the time. Now it exists, and physicists are ignoring it trying to push information out the back door, while we're finding it coming in through the front door all of a sudden. Now the theory of Entropic gravity is taking hold, and it's becoming clear that this dual view of things is how you have to deal with physics. As Wheeler put it..."matter tells spacetime how to curve, and curved spacetime tells matter how to move." Well that's all smoke and mirror tricks until you take a dual view of spacetime AND information (yes, another physics duality...it's nothing new guys so don't be afraid...this is exactly wave/particle duality fully geometrized, just how we like things). So if you're a physicist, get on board the duality train, because this is the future. This is the beginning of a grand unification in a very real sense.

@ Nicholas W: I really wish you had broke that into a few more paragraphs, so very hard to read...however, this has been precisely my train of thought for 10 years now.

The more I studied GR and the work being done in grand unification, the less comfortable I was with gravity being a force at all. Thank you for your post, it was a breath of fresh air, dood.

If you insist on the probability interpretation of the wave function you are not only stuck with superluminal velocity, your collapse of the wave function needs to be psychic enough to find the other particle, which may be located arbitrarily far across the universe. How can you stand it? What is wrong with the wave function being physical, like in the case of light, the wave function is light? In the case of pair annihilation two oppositely traveling gamma rays will have crossed polarizations (nearly). This will then determine, at least partially, the polarized-direction outcome at each detector. I also include a pre-loaded unknown state of the detector when I think of these things.

Originally Posted by Azure Infinity

@ Nicholas W: I really wish you had broke that into a few more paragraphs, so very hard to read...

Agreed, though it's wonderfully stated! Nice job, Nicholas.

Excellent. A new approach - maybe the first since the discovery of local symmetry. Thanks

We chat about the possibility time may be multidimensional similar to space. Might account for several of the 11 dimensions space is thought to have.

Excellent explanation I thought. I felt something the instant you wrote it.