Probability Distribution for Time of Measurement?

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Discussion Overview

The discussion revolves around the concept of probability distribution for the time of measurement in quantum mechanics, specifically in relation to the time evolution of a wave function and the detection of an electron. Participants explore the existence of a function that describes the probability of registering a measurement within a specific time interval.

Discussion Character

  • Exploratory, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant questions whether a function f(t) exists that provides the probability of a detector registering a measurement in the interval (t, t+dt) after the wave function evolves from a position eigenstate.
  • Another participant expresses agreement with the question and shares their own uncertainty about the existence of a theory regarding time probability density, suggesting it is a complex topic that may not be well understood.
  • A third participant suggests searching for "time of arrival" for more information on the topic.
  • A fourth participant provides a reference to a specific paper on time-of-arrival in quantum mechanics, indicating that there are existing discussions in the literature.
  • Another participant expresses interest in the topic and acknowledges the contributions of others in the discussion.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the existence of a probability density function for time of measurement, and multiple viewpoints regarding the complexity and understanding of the topic are presented.

Contextual Notes

The discussion highlights uncertainties regarding the theoretical framework for time probability density in quantum mechanics and the potential for existing theories that are not widely known.

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Say we have an electron in a position eigenstate [itex]\delta(P-x)[/itex] at point [itex]P[/itex] at time [itex]t_0[/itex]. We also have a detector at another point Q. At [itex]t_0[/itex], the probability of the detector registering the electron is zero. After a certain time [itex]T[/itex], the time evolution of the wave function generates a non-zero probability for the electron to be found at Q, but what can we say about the time of measurement? Is there a function [itex]f(t)[/itex] such that [itex]f(t)dt[/itex] gives the probability that the detector will register a measurement in the interval [itex](t, t+dt)[/itex]?
 
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Excellent question!

Sorry for not answering it, though. I merely wanted to say that if you had not asked this, I might have been asking the same thing at some point. I had actually already started to preparing some kind of question about this topic (that's why I think this is an excellent question :biggrin:), but I've still been too busy with some other problems, and replies to my other questions.

When you know that some theory exists, it is a simple thing to tell about it.

But when you don't know that some theory exists, it becomes dangerous to claim that it wouldn't exist. It could be that you just haven't heard about it, but somebody else has, and somebody could prove you wrong.

This probability density with respect to time seems to belong into this difficult category of topics, where everybody merely wants to keep mouth shut in order to avoid saying anything wrong. I've been speculating that some kind of "effective collapsing density" should exist, but I don't really know how it should work.

Fortunately we have some scientists who are ready to go through the effort of actually finding out what is known and what is not known, and I'm probably not wrong to guess that Demystifier belongs into this group? :smile: I'm looking forward to hear his comment on this (sorry for creating pressure :wink:)
 
You can get more info by searching the web and/or arXiv for "time of arrival"
 
Very interesting, meopemuk.
 

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