5 ms·

> And just as measuring the trajectories of particles seems to “collapse” their simultaneous realities, disturbing the pilot wave in the bouncing-droplet exper

by snarfy 12y ago

> And just as measuring the trajectories of particles seems to “collapse” their simultaneous realities, disturbing the pilot wave in the bouncing-droplet experiment destroys the interference pattern. Did we read the same article? Pilot wave theory has the same mathematics as quantum mechanics. It's a different interpretation of those mathematics - the probability wave is real and physical.

Zigurd 12y ago
I read that. Note that it says "disturbing the pilot wave." That's not "measuring." The sentence is trying to draw an analogy with "collapse." But to do that you have to explicitly "disturb" the pilot wave. In these droplet experiments, you can measure all you want without affecting the wave and the interference pattern. This might point to an analogous form of quantum mechanics. But it also could be just an interesting but incomplete analogy in classical physics.
- snarfy 12y ago
  It's akin to weak measurement - we can measure which slit the particle goes through without disturbing the interference pattern. http://en.wikipedia.org/wiki/Weak_measurement http://en.wikipedia.org/wiki/Weak_measurement
  - Zigurd 12y ago
    I'm not seeing how that is so. You can measure every aspect of the oil drop at every point along the path it takes, before and after and as is passes through the slits and it won't do a darn thing to the pilot wave and the interference pattern. The ability to measure is 100% classical 100% of the time.
    - MacsHeadroom 12y ago
      We can measure every aspect of the oil droplet because we're measuring it with trillions upon trillions of infinitely smaller and faster photons which give us a great insight without disturbing the structure. What would we bounce off of photons to get an equally accurate picture without disturbing them? The analogy isn't a problem. The fact that there's nothing small enough to observe photons like we can observe the oil is a problem, but it says nothing about the integrity of the analogy. In the analogy the water is space-time, meaning "observing" the droplet like we observe photons would require shooting another droplet past or into the first droplet.
      - morpher 12y ago
        I agree with your first two paragraphs. But, be careful about the last. The pilot wave in Bohmian mechanics is not a wave in space time, but rather a separate physical entity. Basically the dynamics of both the particle and its pilot wave are described by different portions of the wavefunction. (The wavefunction is complex, and so has enough variables to describe two physical quantities).

by snarfy 12y ago

Zigurd 12y ago

I read that. Note that it says "disturbing the pilot wave." That's not "measuring." The sentence is trying to draw an analogy with "collapse." But to do that you have to explicitly "disturb" the pilot wave. In these droplet experiments, you can measure all you want without affecting the wave and the interference pattern. This might point to an analogous form of quantum mechanics. But it also could be just an interesting but incomplete analogy in classical physics.

snarfy 12y ago
It's akin to weak measurement - we can measure which slit the particle goes through without disturbing the interference pattern. http://en.wikipedia.org/wiki/Weak_measurement http://en.wikipedia.org/wiki/Weak_measurement
- Zigurd 12y ago
  I'm not seeing how that is so. You can measure every aspect of the oil drop at every point along the path it takes, before and after and as is passes through the slits and it won't do a darn thing to the pilot wave and the interference pattern. The ability to measure is 100% classical 100% of the time.
  - MacsHeadroom 12y ago
    We can measure every aspect of the oil droplet because we're measuring it with trillions upon trillions of infinitely smaller and faster photons which give us a great insight without disturbing the structure. What would we bounce off of photons to get an equally accurate picture without disturbing them? The analogy isn't a problem. The fact that there's nothing small enough to observe photons like we can observe the oil is a problem, but it says nothing about the integrity of the analogy. In the analogy the water is space-time, meaning "observing" the droplet like we observe photons would require shooting another droplet past or into the first droplet.
    - morpher 12y ago
      I agree with your first two paragraphs. But, be careful about the last. The pilot wave in Bohmian mechanics is not a wave in space time, but rather a separate physical entity. Basically the dynamics of both the particle and its pilot wave are described by different portions of the wavefunction. (The wavefunction is complex, and so has enough variables to describe two physical quantities).