Greene on the Most Mind-Boggling Result

Brian Greene answers questions:

And I'd say the most mind-boggling result of quantum 1:44:38 mechanics is the result of John Bell, John Stewart Bell, ...

But he was not willing to accept quantum entanglement at face value. He wanted to know if a version of quantum mechanics might be constructed that would be that would be local that wouldn't have these spooky non-local influences.

and he was trying to realize a dream really of Albert Einstein who thought that might be possible to come up with a new theory that embraces the same predictions as quantum mechanics but doesn't have this weird spooky action and he worked very hard thought he was coming very close to formulating that theory but every time he got to the near to the end it fell apart.

so finally he said to himself maybe this is a fool's errand maybe it's impossible to have a theory that agrees with the predictions of quantum mechanics and yet somehow excises spooky action non-local influences and he proved that that is the case a beautiful theorem John Bell proved a theorem which then because of the experimental data being such as to confirm the version that I just described that any quantum mechanically uh viable theory that agrees with the predictions of the standard approach is necessarily non-local. And so that to me is the most stunning implication. We necessarily live in a nonlocal universe. Yeah.

In fact, as a small teaser, I'll mention I'm actually writing a new book on quantum mechanics.

It is going to be a horrible book.

Quantum mechanics does not have any spooky non-local influences. Bell only proved that it differs from a type of local classical theories. It left open the possibility that a spooky classical theory might agree with QM, but that is not what Einstein was looking for.

Greene is famous for promoting string theory and multiverse theories. He now admits that these are speculative and unproven. Next he is going to promote quantum spookiness.

Meanwhile, Dr. Bee is writing a similar book and ventures into spookiness in her latest video on You probably misunderstand the double slit experiment. She is mostly correct, but goes off the rails when she says it proves either superdeterminism or spookiness:

4:37 But if the particle went through the other slit, you never interacted with it. You didn't touch the particle. It just knew you were trying to. The only way that you can avoid this faster than light update is that the particle knows whether you'll measure it before you've made the decision whether to measure it or not. This is what's called super determinism. And this is what's so weird about the double slit.

The error is that she keeps talking about particles, as if each has a definite position and momentum even when not observed. They do not. They are really waves, and waves always make interference patterns when going throught a double-slit, or even a single slit. There is no need to invoke spookiness or superdeterminism.

She refers to another quantum oddity. If you fire an electron at a double slit, it is really a wave that goes through both slits. If you put detectors on the slits, you only find one electron. If you observe the electron in one slit, you can be sure that the other detector will not see it. Conversely, if a detector says no electron went through one slit, then the other detector will see it in the other slit.

She describes this as very strange:

You make a measurement at one slit and the wave function on the other slit 4:22 changes immediately. And note that this is the case even if the particle does not trigger the detector. If it doesn't go into the detector, you know it must have gone through the other slit. But if the particle went through the other slit, you never interacted with it. You didn't touch the particle. It just knew you were trying to.

It is not so odd. Suppose I put my car key in my pocket, and I forget which of my two pockets. I can reach into one pocket, find it empty, and immediately deduce that my key is in the other pocket. I am finding my key, without interacting with it. It is not spooky or superdeterministic. The key did not know that I was looking for it.

It is peculiar to QM that measurements give eigenvalues. The theory says that the (unmeasured) electron goes partially through each slit. It could even tunnel through a barrier. But you never observe half an electron or an electron being in two places at once. Those are the real quantum mysteries. But the spookiness and superdeterminism are just nonsense.