According to the current consensus among physicists, yes, you're wrong. The end product of the Bohr-Einstein debate was that Einstein figured out a way to settle the question experimentally instead of by debate. The experiment is difficult; the technology to do it didn't exist until the 1980s, long after both men were dead. But by now it's been carried out many times. Bohr always wins.
Here are
the gory details.
Or if you want, I can try my hand at explaining why the consensus is for Bohr, if you're up for a little trigonometry.
Can you explain how Bell's theorem rules out originating points in spacetime as local variables for entanglement?
In other words, if 2 particles are entangled does Bell's theorem define the originating spacetime point (where the entanglement began) as a local variable?
It doesn't rule them out as local variables -- everything that happens at the originating point counts as a local variable as far as Bell's theorem is concerned. But it rules out the possibility that what happens to one particle depends only on events at the originating point and along its own trajectory from it, because QM predictions come true. What happens to one particle also depends on what happens to the other particle after they separate. The explanation is kind of complicated, but here goes...
Barium borate is an unusual material. When a laser beam goes through it, occasionally a photon is "down converted" -- broken into two photons, each with twice the wavelength and half the energy of the incoming photon. These photons come out at an angle, on opposite sides of where the laser beam comes out. The two photons that came from a given input photon always have opposite polarizations. If you test them to see if they're polarized horizontally or vertically, you always find one is horizontal and the other is vertical. If instead you test them to see if they're polarized at 45 degrees or 135 degrees, you always find one is 45 degrees and the other is 135 degrees, and so on.
But you can't actually test a photon to accurately find out what angle it's polarized at. There's no way to build a detector that will do that -- QM doesn't let you ask that question. QM only allows you to get one bit of information about what its orientation was before it was measured. (After it's measured you will of course have lots of bits -- "it's at 45 degrees", for instance -- but when you measured it you changed it.) So first you have to pick the angle to set your detector at, and then when the photon goes in, the detector will only tell you "parallel" or "perpendicular". That's all you get.
So what happens if you take a photon you already know is at 30 degrees and send it into a detector oriented horizontally? The detector can't tell you "30 degrees". All it can tell you is "0 degrees" or "90 degrees". So which is it, 0 or 90? Well, it's random. Usually it says "0 degrees"; sometimes it says "90 degrees". If you send in a photon polarized at 45 degrees, your detector will say 0 half the time and 90 half the time; but 30 is closer to 0 than it is to 90, and that means from a 30 degree photon you're more likely to get a 0 answer than a 90 answer.
But this is where the QM devil is: in the trigonometric details.
Exactly how much more likely? It turns out the the formula is pretty simple: it's the square of the cosine of the angle. The square of the cosine of 30 degrees is 0.75. That means when a 30 degree photon goes into a horizontal polarization detector, the detector has a 75% chance of saying the photon is horizontal and a 25% chance of saying it's vertical.
So where does that leave us with the down-converted photons? You get two beams of polarized photons out of your barium borate crystal; let's say you send them to two labs, hundreds of miles apart. You have several detectors in each lab, set up at various angles. The scientist in each lab can pick which detector to send a photon into, at a moment's notice. So let's say they each get a sequence of four photons, and they've agreed to send them into their respective horizontal detectors. Then the left scientist and the right scientist might get results like this:
...L R
...- -
0:H V
1:H V
2:V H
3:H V
All the photons mismatch -- the two scientists' detectors never say the same thing at the same time. No H H, no V V. The orientation of any given photon is totally random -- they can't ever predict the next one they're going to get -- but since the photons came out of a down converter, the left photon and the right photon are always 90 degrees different from each other. That's what barium borate does to polarization of light. So after they see their own results, both scientists can tell you what the other one saw, even before they compare notes. Contrariwise, if they agreed to have the left scientist use a horizontal detector and the right scientist use a vertical detector, they might see something like this:
V V
H H
H H
V V
Now all the detector reports match. The down converter made each pair 90 degrees apart, and the detectors are 90 degrees apart, and two perpendiculars make a parallel. So each scientist can still figure out what the other one must have seen.
But when their detectors are neither parallel nor perpendicular, they won't be able to reliably say what the other one saw. If one scientist tilts her detector 30 degrees while the other is still horizontal, then they'll see something like this:
H H
H V
V H
H V
Now there will only be three mismatches. The scientists can still make their best guesses about what each other's detectors said, and the left scientist will guess V, V, H, V, and the right scientist will guess V, H, V, H. But they'll only be right three quarters of the time, because of the cosine squared law.
Anyway, that's how the world works -- it's predicted by QM and verified by experiment. So what does Bell's Theorem have to say about all this? First it says, what did the scientists see when they both used horizontal detectors? Suppose for example that they saw this:
H V
H V
V H
H V
All the photons mismatch.
Then Bell's Theorem says, let us reason from the hypothesis that how you measure one photon doesn't affect the other photon hundreds of miles away in the other lab. Well then, what would the left scientist have seen if she'd instead used a 30 degree detector? Could she have seen just any sequence at all? No. Because her decision didn't affect the other lab, it follows that the right scientist would have to have still seen V, V, H, V. Since the detectors are 30 degrees apart, the right scientist can guess that the left scientist saw H, H, V, H, and he'd be right about three quarters of the photons. So, assuming what happens is only influenced by local variables, the left scientist has to see a sequence where only one photon doesn't fit the H, H, V, H pattern. The other 12 possible sequences are ruled out. Only a quarter of the photons would have changed to the other orientation if she'd tilted the detector 30 degrees.
Then Bell's theorem asks, what if, instead, the left scientist had used her original horizontal detector but the right scientist had used a -30 degree detector, i.e. tilted his detector 30 degree in the opposite direction? The same reasoning shows that the left scientist would have still seen H, H, V, H, so she'd guess that the right scientist saw V, V, H, V, and she too would be right on three quarters of the photons. So, assuming what happens is only influenced by local variables, the right scientist has to see a sequence where only one photon doesn't fit the V, V, H, V pattern. Maybe V, H, H, V, maybe V, V, H, H, but definitely not H, H, H, H.
Finally, Bell's theorem asks, what would have happened if both the left scientist had used a 30 degree detector and also the right scientist had used a -30 degree detector? Since what happens is only influenced by local variables, the result would have to be just the combination of what we just figured out for the two of them separately. One scientist changes the left detector angle by 30 degrees and that makes one of her photon observations flip. The other scientist changes the right detector angle by 30 degrees and that makes one of his photon observations flip. That makes two flipped observations. Originally there were four mismatches, so this usually means two photon pairs out of four don't mismatch any more. (Occasionally it means they all still mismatch, for instance if in both labs it was the third photon that would have been the one to flip.) That's the famous "Bell Inequality" -- if we assume the hypothesis that what happens is only influenced by local variables, then the number of photon pairs that match in the two labs has to be less than or equal to two.
The trouble is, in point of fact, in the real world, if we actually tilted the detectors as described, then the 30 degree detector in the left lab and the -30 degree detector in the right lab would be rotated
60 degrees apart from each other. And the square of the cosine of 60 degrees is 0.25. So, by the rules of QM and by experimental test, we know there would only be one mismatching pair out of four. There will be three matched pairs. (Recall that when the detectors are 90 degrees apart from each other, you get four matches out of four.) What happens in the two labs turns out to be more strongly correlated than any local variable explanation could possibly predict.
So that's it. That's how Bell's theorem rules out local variables, at the originating points in spacetime, or anywhere else, as explanations for quantum correlations. That's why the consensus among physicists is that Bohr was right, that Einstein was wrong, that there really is spooky action at a distance, and that nature really is as psychotic as quantum mechanics looks.
(Disclaimer: In order to make the explanation simpler, I've been talking about just four photons in each lab and pretending that average behavior happens every time -- that a 75% probability means when you see 4 photons, 3 go one way and 1 goes the other way. But really 4 photons is far too small a sample size to expect average behavior every time. Sometimes things break two and two, or all four go the same way, just by chance. So to make the above chain of reasoning rigorous, I'd need to rewrite the whole thing with a lot more than 4 photons. But the principle still applies. 400 photons on each side, 400 mismatches when both detectors are horizontal, local variables imply that each independent detector tilt will flip about a hundred observation results, which means after two detector tilts there must necessarily be about 200 matches or fewer. And then reality breaks your balls and delivers about 300 matches.)
Is spacetime considered to be a non-local variable if a whole new "spacetime branch" (MWI) comes into existence at every entanglement?
I don't understand MWI well enough to touch that one with a ten foot pole.
