3 ms·

Bohm's interpretation is definitely one of the more reasonable ones and I think it's a fine picture to have in your head. But it suffers from two major flaws.

Bohm's interpretation is definitely one of the more reasonable ones and I think it's a fine picture to have in your head. But it suffers from two major flaws. 1. There is no need for the particle It's superfluous structure, which has no effect on the dynamical evolution or predictions. Only the pilot wave is needed, so that's a straightforward violation of Occam's razor. 2. It has FTL influences They may not be exploitable to us, but the primitive ontology of the theory requires it. This is seriously against the spirit of special relativity. In my view, Bohm's theory is only suitable as a visual aid or for those who are in denial about the consequences of pure unitary dynamics.

szemet 9y ago
suitable as a visual aid Especially the somewhat related silicon droplet videos on youtube, e.g.: https://www.youtube.com/watch?v=WIyTZDHuarQ https://www.youtube.com/watch?v=WIyTZDHuarQ
alien_at_work 9y ago
>so that's a straightforward violation of Occam's razor. I'm probably missing something but I don't get this objection entirely. I've long considered Occam's razor just a thing you can say. It doesn't have any predictive power as far as I can tell. The complex answer is just as likely to be correct as the simple one [1]. [1] http://neuralnetworksanddeeplearning.com/chap3.html http://neuralnetworksanddeeplearning.com/chap3.html Search for "Occam's razor"
- akvadrako 9y ago
  It's not about complex vs simple, but about adding unnecessary assumptions. At least, that's the strict form of Occam's razor which I'm using here. If I have two theories: 1. which says that the Earth orbits the Sun and predicts when seasons and sunrises occur 2. the same as 1, plus undetectable pink elephants are floating through space Then Occam's razor says we should discard the second, because it just adds an assumption without adding predictive power. Or more plainly, if my axioms are a = 2b and a = b^2 then adding the axiom sqrt(a) = b creates a strictly inferior theory.
  - alien_at_work 9y ago
    Ok, that makes more sense. I guess the problem, as always, is "people on the internet" using it like "that sounds more complicated so it must be wrong".
  - jostylr 9y ago
    Using just the wave function alone is similar to saying that in specifying the computation sin(x) where x = 3, you do not need to say x=3 because the value of sin(3) is part of sin(x) so why do we need to talk about sin(3) by itself? Of course, we talk about 3 because we have some need of it. In dBB, we have need of particles because they explain our experience in a fashion that is readily apparent. At a first approximation, stuff moving around in 3-space is exactly what we experience. The question then becomes figuring out the motions of that stuff. If the stuff in the theory moves in the right position in our experience, then we can keep that theory as a plausible candidate for predictions. The particles drive the need for the wave function. In many ways, the wave function is acting in a fashion like the law of gravity in Newtonian physics. Fix the law, start with different initial conditions, and we get a different history. One of those histories might just conform to our experience and we would then be satisfied. Without the particles, we have a complex-valued function on configuration space. Why is there 3-space in our experience? Why do we have a feeling of some definiteness in the outcome of experiments? The wave function provides none of that and these are essential ingredients to what we would like to get from the theory.
    - akvadrako 9y ago
      I like your point about needing to localise yourself in the wavefunction to make sense of your experience. That's true and how to do so is less obvious in pure unitary dynamics. I think the essential issue is that Bohm's theory makes a distinction between "actual" things and "real" things. But if you drop that philosophical distinction then it's clear that the wave-function and all points on it must exist, because otherwise they couldn't influence you. Those points near you will flow through the universe in a similar way and have the same interactions with nearby points. So yes, the point particle is a useful visual aid, but it doesn't work if the other points on the wave don't exist too. Your other arguments about 3D space and definite outcomes are weaker. 3D space emerges from the structure of entanglement and the "feeling" of definite outcomes is caused by decoherence. In pure wave mechanics the spacetime locality of interactions is also apparent, while in dBB they are necessarily non-local. Since spacetime is all about locality, the picture in pure wave mechanics is superior.

szemet 9y ago

suitable as a visual aid Especially the somewhat related silicon droplet videos on youtube, e.g.: https://www.youtube.com/watch?v=WIyTZDHuarQ https://www.youtube.com/watch?v=WIyTZDHuarQ

alien_at_work 9y ago

>so that's a straightforward violation of Occam's razor. I'm probably missing something but I don't get this objection entirely. I've long considered Occam's razor just a thing you can say. It doesn't have any predictive power as far as I can tell. The complex answer is just as likely to be correct as the simple one [1]. [1] http://neuralnetworksanddeeplearning.com/chap3.html http://neuralnetworksanddeeplearning.com/chap3.html Search for "Occam's razor"

akvadrako 9y ago
It's not about complex vs simple, but about adding unnecessary assumptions. At least, that's the strict form of Occam's razor which I'm using here. If I have two theories: 1. which says that the Earth orbits the Sun and predicts when seasons and sunrises occur 2. the same as 1, plus undetectable pink elephants are floating through space Then Occam's razor says we should discard the second, because it just adds an assumption without adding predictive power. Or more plainly, if my axioms are a = 2b and a = b^2 then adding the axiom sqrt(a) = b creates a strictly inferior theory.
- alien_at_work 9y ago
  Ok, that makes more sense. I guess the problem, as always, is "people on the internet" using it like "that sounds more complicated so it must be wrong".
- jostylr 9y ago
  Using just the wave function alone is similar to saying that in specifying the computation sin(x) where x = 3, you do not need to say x=3 because the value of sin(3) is part of sin(x) so why do we need to talk about sin(3) by itself? Of course, we talk about 3 because we have some need of it. In dBB, we have need of particles because they explain our experience in a fashion that is readily apparent. At a first approximation, stuff moving around in 3-space is exactly what we experience. The question then becomes figuring out the motions of that stuff. If the stuff in the theory moves in the right position in our experience, then we can keep that theory as a plausible candidate for predictions. The particles drive the need for the wave function. In many ways, the wave function is acting in a fashion like the law of gravity in Newtonian physics. Fix the law, start with different initial conditions, and we get a different history. One of those histories might just conform to our experience and we would then be satisfied. Without the particles, we have a complex-valued function on configuration space. Why is there 3-space in our experience? Why do we have a feeling of some definiteness in the outcome of experiments? The wave function provides none of that and these are essential ingredients to what we would like to get from the theory.
  - akvadrako 9y ago
    I like your point about needing to localise yourself in the wavefunction to make sense of your experience. That's true and how to do so is less obvious in pure unitary dynamics. I think the essential issue is that Bohm's theory makes a distinction between "actual" things and "real" things. But if you drop that philosophical distinction then it's clear that the wave-function and all points on it must exist, because otherwise they couldn't influence you. Those points near you will flow through the universe in a similar way and have the same interactions with nearby points. So yes, the point particle is a useful visual aid, but it doesn't work if the other points on the wave don't exist too. Your other arguments about 3D space and definite outcomes are weaker. 3D space emerges from the structure of entanglement and the "feeling" of definite outcomes is caused by decoherence. In pure wave mechanics the spacetime locality of interactions is also apparent, while in dBB they are necessarily non-local. Since spacetime is all about locality, the picture in pure wave mechanics is superior.