The cause of particle going through one slit of the other

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Discussion Overview

The discussion revolves around the double slit experiment, specifically addressing how particles, referred to as "wavicles," pass through the slits and the implications for conservation of momentum. Participants explore the nature of particle behavior, interference, and the role of wave functions in quantum mechanics.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants assert that particles go through one slit or the other in a roughly 50/50 ratio, questioning how this does not violate conservation of momentum.
  • Others argue that in the presence of interference, it is not meaningful to assign a specific slit to a particle, as this would disrupt the interference pattern.
  • A participant mentions that the uncertainty principle limits the precision of the momentum and position of particles, affecting how beams are formed and measured.
  • It is noted that not all incident particles pass through the slits; some are scattered or absorbed, which complicates the discussion of momentum conservation.
  • There is a distinction made between the wave function and the physical particle, with some participants emphasizing that the wave function's interpretation varies among different quantum mechanics frameworks.

Areas of Agreement / Disagreement

Participants express differing views on the nature of particles passing through the slits and the implications for momentum conservation. There is no consensus on the interpretation of the wave function or the specifics of particle behavior in the experiment.

Contextual Notes

The discussion highlights limitations related to the definitions of wave functions and particles, as well as the implications of the uncertainty principle on experimental setups. The varying interpretations of quantum mechanics also contribute to the complexity of the arguments presented.

susskind99
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In the double slit experiment wavicles go through one slit of the other in roughly a 50/50 ratio. How does this not violate conservation of momentum? They would need momentum to push them to the right or the left.
 
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If you have interference, they do not go through the slits in any ratio - there is no way to say "this particle went through slit 1", otherwise you would not get interference.
The momentum and the position of your particle are not single, fixed numbers, they can vary a bit.
 
susskind99 said:
In the double slit experiment wavicles go through one slit or the other in roughly a 50/50 ratio. How does this not violate conservation of momentum? They would need momentum to push them to the right or the left.

In experiments, the incident beam, whether laser or electron or other particle, always has a finite cross-section. The intrinsic spread in volume and momentum/energy of particle beams is ultimately a consequence of the uncertainty principle, which imposes limits on the (r, p) precision with which a beam can be formed. The restriction applies even if you do the experimental measurement one particle at a time, or with a hugely collimated beam.

In the lab, you would move your beam about on the diffraction slits (or vice versa) until you see the strongest signal (meaning that the spot is centred near the slits).
 
susskind99 said:
In the double slit experiment wavicles go through one slit of the other in roughly a 50/50 ratio. How does this not violate conservation of momentum? They would need momentum to push them to the right or the left.

The particles that go through one of the slits go through one or the other in a 50/50 ratio. First, as mfb said, you need which-way information for it to be sensible to talk about particles going through either slit. Second, plenty of the incident particles do not go through either slit; they're scattered off or absorbed by the barrier and never detected. The wavefunction of each individual particle is a wavepacket that is spread out along all three spatial axes (and the packet spreads out more as it propagates). When the wavefunction reaches the barrier, some of it is scattered back, some of it is absorbed, and some of it diffracts through the two slits. If the beam is properly centred on the slits, then the proportion that "leaks through" either slit will be the same and a which-way modification to the experiment would show a 50/50 split between the two slits.
 
What reaches the barrier, the waveform, and/or the wave function?
 
The wave function is not a physical entity...it is the particle that reaches the slit/barrier.
 
gadong said:
The wave function is not a physical entity...
That depends entirely on your favorite interpretation of quantum mechanics.
 

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