Is the Delayed Choice Experiment Justified?

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Discussion Overview

The discussion revolves around the Delayed Choice Experiment, particularly the implications of time perception for particles like electrons and photons in the context of quantum mechanics. Participants explore the conceptual understanding of how these particles behave when observed and the nature of time in relation to their travel.

Discussion Character

  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant expresses discomfort with the standard interpretation of the Delayed Choice Experiment, questioning whether it is justified given the implications that particles "know" they are being observed.
  • The same participant argues that from the electron's perspective, no time elapses when it travels, suggesting that the notion of a "delay" may not apply.
  • Another participant corrects the initial claim about electrons traveling at the speed of light, stating that electrons can never reach light speed, thus time does not stop for them, but may be experienced differently at high velocities.
  • A later reply acknowledges the correction and shifts the focus to photons, suggesting that if photons are considered, the original argument about the absence of delay might still hold.
  • One participant mentions a FAQ that could provide additional insights into how light might 'experience' time, indicating a desire for further clarification on the topic.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the interpretation of the Delayed Choice Experiment. There are competing views regarding the nature of time for different particles, and the discussion remains unresolved.

Contextual Notes

There are limitations in the discussion regarding the assumptions made about time perception for particles and the definitions of speed in the context of relativity. The relationship between observation and particle behavior is also not fully explored.

lmerriam
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Hello,

I'm uncomfortable with the usual description of this experiment and wonder if this is justified. In a nutshell, when (in the usual double-slit setup) detectors are placed between the barrier and the final screen -- such that an electron, say, has already passed the two-slits -- an interference pattern will still form as though the detection had been made earlier. It is then suggested that the electron knows it was watched and adjusts its behavior in the past to conform accordingly.

Here's my problem with this ...

Electrons travel at the speed of light where time either does not exist at all, or perhaps simply stops (I recall reading it is the former .. is this correct, btw??). Regardless ... although from our perspective the electron most certainly crossed the barrier before it reached the detector beyond, from the electron's point of view no time elapsed at all; hence, there was no delay to speak of.

Am I missing something?

thanks!
 
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lmerriam said:
Hello,

I'm uncomfortable with the usual description of this experiment and wonder if this is justified. In a nutshell, when (in the usual double-slit setup) detectors are placed between the barrier and the final screen -- such that an electron, say, has already passed the two-slits -- an interference pattern will still form as though the detection had been made earlier. It is then suggested that the electron knows it was watched and adjusts its behavior in the past to conform accordingly.

Here's my problem with this ...

Electrons travel at the speed of light where time either does not exist at all, or perhaps simply stops (I recall reading it is the former .. is this correct, btw??). Regardless ... although from our perspective the electron most certainly crossed the barrier before it reached the detector beyond, from the electron's point of view no time elapsed at all; hence, there was no delay to speak of.

Am I missing something?

thanks!
---

Yes. Electrons do not travel at the speed of light. They may be at any velocity from standstill to almost light-speed, but they will never actually be at the speed of light. Hence, time may be shortened for them but it never actually stops per se.
 
Ouch! And thanks for correcting me. I should have said photons which, unlike electrons, are mass-less. In this case, there would be no delay at all, and the original argument survives ... no?

SewerRat said:
---

Yes. Electrons do not travel at the speed of light. They may be at any velocity from standstill to almost light-speed, but they will never actually be at the speed of light. Hence, time may be shortened for them but it never actually stops per se.
 
There is a FAQ here, but I don't know where (sorry!) about how "light" might 'experience' time. I think it would be helpful... maybe an adviser or mentor can link?
 

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