Particle in Box: Zero Probability Density at Certain Points

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Discussion Overview

The discussion revolves around the implications of zero probability density at certain points for a particle in a box within quantum mechanics. Participants explore the interpretation of probability density in relation to particle movement and measurement, focusing on theoretical and conceptual aspects.

Discussion Character

  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants argue that zero probability density does not imply that the particle cannot move across those points, as this assumes a classical trajectory tracking of the particle.
  • Others emphasize that probability density indicates the likelihood of finding the particle upon measurement, rather than its ability to traverse certain points.
  • A participant suggests that to understand particle behavior at points of zero probability density, one should refer to the Schrödinger equation.
  • Another participant critiques the original question for using classical terminology, proposing that it should focus on the probability of finding the particle in specific regions rather than its movement.
  • It is noted that if the state is an eigenstate, the probability density remains constant, but measuring at a point of zero width will always yield a probability of zero.

Areas of Agreement / Disagreement

Participants express differing views on the interpretation of zero probability density and its implications for particle movement. There is no consensus on the original question's framing or the implications of the probability density concept.

Contextual Notes

The discussion highlights limitations in the original question's assumptions and terminology, particularly regarding classical versus quantum interpretations of particle behavior and measurement.

somebody-nobody
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The probability density at certain points for a particle in a box is zero.Does this imply that the particle cannot move across these points
 
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somebody-nobody said:
The probability density at certain points for a particle in a box is zero.Does this imply that the particle cannot move across these points

No, because by saying that, you are assuming that you CAN track the particle's trajectory every step of the way. All the probability density says is that when you make a measurement, the probability of finding the particle at the nodes is zero.

Zz.
 
somebody-nobody said:
The probability density at certain points for a particle in a box is zero.Does this imply that the particle cannot move across these points

Like ZapperZ said, the probability density merely defines where you can find the particle when you measure. To figure out if a particle will ever move in a spot of "zero", you should use the Schrödinger equation.
 
ZapperZ said:
No, because by saying that, you are assuming that you CAN track the particle's trajectory every step of the way. All the probability density says is that when you make a measurement, the probability of finding the particle at the nodes is zero.

Zz.
Yep. The proplem is with the question itself. The OP used the term move, which is a classical idea and not a quantum one. The question is better asked regarding what the probability of finding the particle in this region and then ask what the probability of measuring the particle in this other region after the first measurement was made. If the state is an eigenstate (stationary state) the the probability density will remain constant. But we really don't speak of measuring a particle in a region of zero width (i.e. what's the probability of finding the particle at x = 2?) because that will always be zero.

Pete
 

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