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Could I ask a question? As you are clearly someone with a deep knowledge QM. Why is Bohmian mechanics so frequently dismissed? It's such a straight forward pre

Could I ask a question? As you are clearly someone with a deep knowledge QM. Why is Bohmian mechanics so frequently dismissed? It's such a straight forward premise - there is an actually physical guiding wave and everything else falls out "normally". Instead pages are written about MWI and hypothetical agents optimizing their overall decision in universes they'll never see. And undefinable concepts of trillions of universes splitting simultaneously. And I'm not trying to be snarky at all, as I feel what you wrote above is one of the best presentations od the topic I've seen. To be perfectly frank QM is starting to scare me about physics. To a layman which I am, Bohmian mechanics is so simple and straightforward it's almost "obviously right". The macroscopic analogy of Farady waves is almost a nail in the coffin (to a layman). Allow for non-locality of guiding waves, just like ripples on a lake and everything else is deterministic and matches all scientific observations. Events have probability for the same reason the weather has probability: because we can't measure with the sensitivity required to account for the complexity of the system and the difference in initial conditions. And yet, I've never seen any write up against Bohmian. I've never seen anyone with deep knowledge on the subject discuss why Bohmian isn't the best interpretation. It's just dismissed as an "also-ran". What scares me is 20 years from now something will emerge making it clear that Bohmian is the "correct" interpretation. And then the question in my mind will be, "what took it so long to even be seriously considered?". It would be proof to me that physicis is being shifted from investigating and following up on the best explanation for data to instead becoming "lawyers" trying to find data to support their favorite pre-decided argument (ie their favorite QM interpretation). Now all of that said, there is a reason why laymen don't make meaningful contributions to a field. Their are deeper complexities that make their intuitions wrong. But why are these flaws in Bohmian never discussed? Would you mind taking even a few sentences to write up "what's wrong with Bohmian" that would make the infinitely more complex MWI a more likely candidate? I'm lost. [1] - http://www.tcm.phy.cam.ac.uk/~mdt26/tti_talks/deBB_10/bush_tti2010.pdf http://www.tcm.phy.cam.ac.uk/~mdt26/tti_talks/deBB_10/bush_t...

drcode 7y ago
I'm not qualified to answer your question, but I'm guessing it'll boil down to "Bohmian mechanical interpretation is more mathematically complicated than the others. Therefore, even though it is the least counter-intuitive of the possibilities, Occam's Razor still requires us to discount it because of the complexity."
lisper 7y ago
The best place to find the answer to this question that I know of it David Z. Albert's excellent book, "Quantum Mechanics and Experience." But the short answer to your question is that Bohmian mechanics has two problems: 1. In order to account for the outcome of Bell-type experiments on entangled particles it has to assign a temporal ordering to space-like separated events. The technical term for this is that you have to choose a "preferred foliation of space-time". There has to be a preferred reference frame. But you can never actually know what the preferred reference frame actually is. 2. Yes, particles "have positions", but you can never actually know what those position are (which is why I put "have positions" in scare quotes). This is where all the quantum randomness hides in Bohmian mechanics. It's all "pre-computed" in the infinite precision of a particle's position, but that position is necessarily hidden from observation. I call this an IPU, an Invisible Pink Unicorn. It's exactly the same thing as universe-weights in MWI -- a set of numbers that are part of the theory but rendered immune from observation not by practical limitations on technology, but by the theory itself. This is the fundamental problem with all attempts to make quantum mechanics look deterministic. The simple fact of the matter is that it's not deterministic, so any attempt to make it look deterministic that makes the same predictions as QM has to hide the randomness somewhere. Bohm hides it in particle positions, and MWI hides it in universe weights. But it doesn't matter what you call the place in the theory where you've hidden the randomness. What matters is that there is a place in the theory where you've hidden the randomness, where it must forever remain hidden from the prying eyes of experiment. So the claims that both Bohm and MWI make of being deterministic are misleading at best.
- hackinthebochs 7y ago
  >but that position is necessarily hidden from observation. I call this an IPU, an Invisible Pink Unicorn. But why expect that all state of the universe be open to observation? This seems counter-intuitive to me. It seems far more reasonable that there necessarily are facts about an implementation that no supervening system can determine from within that system. For example, there are facts about a physical computer that no software running on that computer could deduce. So the fact that a QM theory posits state that is in principle off-limits to observation doesn't seem like a reductio, but the expected case.

drcode 7y ago

I'm not qualified to answer your question, but I'm guessing it'll boil down to "Bohmian mechanical interpretation is more mathematically complicated than the others. Therefore, even though it is the least counter-intuitive of the possibilities, Occam's Razor still requires us to discount it because of the complexity."

lisper 7y ago

The best place to find the answer to this question that I know of it David Z. Albert's excellent book, "Quantum Mechanics and Experience." But the short answer to your question is that Bohmian mechanics has two problems: 1. In order to account for the outcome of Bell-type experiments on entangled particles it has to assign a temporal ordering to space-like separated events. The technical term for this is that you have to choose a "preferred foliation of space-time". There has to be a preferred reference frame. But you can never actually know what the preferred reference frame actually is. 2. Yes, particles "have positions", but you can never actually know what those position are (which is why I put "have positions" in scare quotes). This is where all the quantum randomness hides in Bohmian mechanics. It's all "pre-computed" in the infinite precision of a particle's position, but that position is necessarily hidden from observation. I call this an IPU, an Invisible Pink Unicorn. It's exactly the same thing as universe-weights in MWI -- a set of numbers that are part of the theory but rendered immune from observation not by practical limitations on technology, but by the theory itself. This is the fundamental problem with all attempts to make quantum mechanics look deterministic. The simple fact of the matter is that it's not deterministic, so any attempt to make it look deterministic that makes the same predictions as QM has to hide the randomness somewhere. Bohm hides it in particle positions, and MWI hides it in universe weights. But it doesn't matter what you call the place in the theory where you've hidden the randomness. What matters is that there is a place in the theory where you've hidden the randomness, where it must forever remain hidden from the prying eyes of experiment. So the claims that both Bohm and MWI make of being deterministic are misleading at best.

hackinthebochs 7y ago
>but that position is necessarily hidden from observation. I call this an IPU, an Invisible Pink Unicorn. But why expect that all state of the universe be open to observation? This seems counter-intuitive to me. It seems far more reasonable that there necessarily are facts about an implementation that no supervening system can determine from within that system. For example, there are facts about a physical computer that no software running on that computer could deduce. So the fact that a QM theory posits state that is in principle off-limits to observation doesn't seem like a reductio, but the expected case.