Is just watched this Veritasium video.
I find this much easier to understand than all the other explanations I’ve seen.
Why isn’t this interpretation the leading method for explaining to laymen?
Is there anything about quantum mechanics that rules out this interpretation?
I guess it could be like the water analogue for electricity: voltage is pressure, current is water flow etc. Useful but ultimately not a perfect analogue.
All the standard interpretations of quantum theory are mathematically equivalent, therefore all are valid.
I think I’d agree with that - DeBroglie-Bohm (pliot wave) seems less weird because it’s the only (?) deterministic interpretation (one could claim that many-worlds is also deterministic, but to my mind is unclear what the concept means in the context of many-worlds), and the only (?) mainstream interpretation for which counterfactual definiteness holds (again, not clear what that means in many-worlds).
However, bear in mind that DeBroglie-Bohm does require non-locality, instantaneous action at arbitrarily large distances, in principle across the entire universe. That’s not difficult to grasp conceptually, but it’s troubling to physicists (and philosophers). And, although other interpretations such as Copenhagen are also non-local, arguably the non-local action in pilot wave seems even more troubling precisely because pilot wave is deterministic.
In any event, although there’s no evidence to distinguish between the interpretations, physicists do all have their favorites, based I guess on some combination of philosophical views and perhaps a slightly more concrete sense of what is the most “economical” interpretation. And very few physicists think DeBroglie-Bohm is correct, see here for example:
https://www.preposterousuniverse.com/blog/2013/01/17/the-most-embarrassing-graph-in-modern-physics/
So, I think the concise explanation: DeBroglie-Bohm may be conceptually easy to grasp, but if physicists think it’s probably wrong, they aren’t going to teach QM that way.
My feeling (which echos that of the prof who taught me QM) is that pilot wave theory is basically quantum mechanics plus some additional stuff whose sole purpose is to let you continue to believe that there is still a “classical particle” in there somewhere. Or conversely, that there really is a “classical particle”, but there is also a pilot wave that does all of the quantum mechanics and sucks any classical behaviour out of the particle when ever it needs to quantum-y things.
And there is nothing but the desire to maintain some classical intuition about the system that compels people to keep the classical particle around.
I would say rather that the most popular interpretation among physicists is the “shut up and calculate” interpretation, and that most physicists would reject the notion that any of the interpretations even can be more “right” or “wrong” than the others.
Is it fair to say that one interpretation or another may turn out to be more fertile in terms of inspiring illuminating experiments (or modifications of quantum theory)?
I like the pilot wave model, however the last time I studied this, which was admittedly a long time ago, it was strictly a non-relativistic model. Bohm died without having developed a version consistent with special relativity. Thus, all the beautiful results of the Dirac theory of the electron and the quantum electrodynamics of Feynman, Schwinger, and Tomonaga had not been brought into the pilot wave theory. By extension, it could not explain the results of the standard model or any Lorentz invariant quantum field theory. Perhaps that is no longer true, but it would be hard for any physicist to endorse this as the correct interpretation if is strictly non-relativistic. I hope someone succeeds.
They are all simply interpretations of the mathematics of quantum theory. The math is absolutely 100% the same in every interpretation, so the physical predictions of each interpretation are identical. That’s what it means for them to be interpretations, and why practicing physicists are absolutely in favor of the “don’t care” or “shut up and calculate” non-interpretation of the mathematical systems that define quantum behavior.
This isn’t an exact analogy, but if we had two competing theories of gravity with respect to the solar system, one that simply describes the physical results of masses attracting each other, and another that says that angels move the planets according to rules described by the first theory, no serious physicist is going to support the second theory because it doesn’t tell them anything additional. It’s not contradicted by the evidence, and it provides at least some explanation as to why it works the way it does, even if it’s not very good, so people might push it as an explanation for the math, but the real physicists only care about what the equations say, not what some people claim the equations to mean.
One of the ‘selling points’ of Bohmian mechanics is that it derives Born’s rule (a postulate of QM) from a more ‘natural’ postulate (i.e. the quantum equilibrium hypothesis). It has been argued other interpretations can do this, but I doubt many would argue that those derivations are more ‘pleasing’ than Bohm’s derivation. This also though forms a path by which it may be possible to physically distinguish Bomian and quantum mechanics, as it is hardly beyond the realm of imagination that evidence of the quantum equilibrium hypothesis being breached. When the QEH is breached the physical predictions of Bohmian mechanics are different from those of quantum mechanics.
It’s probably easier to describe some problems, or their solutions, in certain interpretations, and it’s certainly easier to come up with ideas by thinking in certain interpretations, but which interpretation that is varies from problem to problem. For instance, Feynman’s techniques for calculating particle interactions arise much more obviously from the sum-over-histories interpretation than from the others (even though that’s about all that sum-over-histories is good for). So there is some profit in being familiar with multiple different interpretations.
I still think instantaneous communication, or information traveling faster than light, is unnecessary to the explanation.
Information flows from cause to effect at the speed of light or less. It’s just that the temporal relationship between cause and effect is reversed from the norm.
Doesn’t widespread acceptance of “spooky action at a distance” also require non-locality, with successive experiments demonstrating this at ever larger distances?
With every interpretation of quantum mechanics, you’re forced to accept something nonintuitive. Nonlocality is one option, but there are others if you hold locality as a must-have.
Non-locality is synonymous with “spooky action at a distance”. I think one thing that’s worth saying is that there’s nothing intrinsically spooky about QM if we just accept QM as the way the universe works. We never observe something that corresponds to classical cause-and-effect that violates SR, we just see correlations that seem to imply it if we try to form a classical intuitive explanation for what’s “really” going on. But that assumes that there’s a “really” underneath.
The Bell’s Inequality experiments rule out Local Realism, so an interpretation cannot have both. Locality means no spooky action. Realism means Counterfactual Definiteness.
De Broglie-Bohm is non-local but has counterfactual definiteness. There are other interpretations that are local but do not have counterfactual definiteness.
(There is loophole to Bell that Local Realism holds but the universe is a conspiracy, but nobody takes this seriously. Superdeterminism.)
Although, to be fair, it’s tough to come up with any argument against superdeterminism that’s any better than “I don’t take that seriously”.
Of course, by definition we cannot prove it either way. But if the superdeterminism “conspiracy” were true, then surely any statistical inference (in the broadest sense) woud be invalid. It seems that we would literally have no grounds to believe that the sun will rise tomorrow. But since statistical inference does seem to work in all of science outside of QM, I think the null hypothesis is surely that it also works in QM. In other words, there’s a strong burden of proof for superdeterminism.
I think the strongest argument in favor of superdeterminism might be the notion that the universe is probably a simulation. The real universe might be fully deterministic, local & realistic, and the simulating agents are just fucking with us with all this QM stuff. QM is basically hyperintelligent aliens trolling us in this simulated universe.
I have never understood any distinction between the universe is a simulation and the universe was created by God other than one uses more science-y terminology.
Is there any true difference that advocates cite?
I agree with you that there’s not much difference. Effective omnipotence and omniscience, and indistinguishable from magic. Although the “Gods” that created the simulation would not be remotely interested in ANY of the ridiculous nonsense that the religious Gods are supposedly interested in, of course! Trolling us with QM is way funnier than talking snakes.
There’s another distinction: that between “created by” and “operated by”.
A putative god(s) could have created reality and then left it to run entirely on its own. Under which assumptions faith would be accurate but prayers pointless.
A different conception of god(s) includes that it/they take action in the ongoing world.
Note that either of those conceptions is consistent with either a deterministic or a non-deterministic world. The design could be either. If we did have evidence of utterly deterministic behavior that would argue that under the second conception the god(s) have the capability to intervene but choose (or at least so far have chosen) not to.
Contrast that with simulations. IMO the way we use the term “simulation” implies there’s some substrate the simulation runs on. Which, at least to my mind, implies an ongoing operator presence. Which in turn means they could intercede on small scales or bigly whenever they wanted for whatever reasons make sense to them.
Bottom line, a simulation argues for the necessary possibility of activist operators = “god(s)”. Which is different from “The world was created by god(s) who are inherently necessarily hands off thereafter.”
For that matter, the operator of a simulation does not necessarily have omniscience nor omnipotence with regards to the simulation. When we humans run simulations, it’s usually because we don’t know how it will end, and wish to find out. And absent the full understanding of the processes we’re simulating, we often find that we can’t get them to behave the way we’d like (supernova simulations, for instance, are infamous for their tendency to not explode).