Is the Screen an Observer in the Double Slit Experiment?

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SUMMARY

The discussion centers on the role of the screen in the double slit experiment and whether it qualifies as an observer in quantum mechanics. The participant expresses confusion regarding the collapse of the probability wave when a screen is introduced, questioning why the photon behaves differently when observed. It is established that the screen does not cause a wave function collapse in the same manner as a conscious observer, and references to Bohm's interpretation are made to clarify the nature of this phenomenon. The conclusion emphasizes that while the screen interacts with the photon, it does not fulfill the criteria of an observer that induces a definitive collapse of the wave function.

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  • Understanding of quantum mechanics principles, specifically wave-particle duality.
  • Familiarity with the double slit experiment and its implications in quantum physics.
  • Knowledge of the concept of wave function collapse in quantum theory.
  • Awareness of Bohm's interpretation of quantum mechanics.
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  • Research the implications of wave-particle duality in quantum mechanics.
  • Study the double slit experiment in detail, focusing on observer effects.
  • Explore Bohm's interpretation of quantum mechanics and its stance on wave function collapse.
  • Investigate the philosophical implications of observation in quantum physics.
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Students of quantum mechanics, physicists interested in foundational interpretations of quantum theory, and anyone seeking to understand the nuances of observation in the double slit experiment.

johny_g
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I am new to this field as will be apparent from my questions. I have a doubt in the basics that has been bugging me for days. This is about the original double slit experiment.

As we all know that in the experiment, there is a double slit and a screen that displays the result of a photon (say) bombardment. My confusion is that I find it hard to understand whether the screen is an observer or not. I mean, the moment we placed a screen in front of the double slit as an act to observe which slit the photon is coming from, the probability wave should have collapsed and the photon should have chosen a single slit to get through (I am focusing only on the result; not the inference).

In other words when there is no background screen, the photon will be taking both slits simultaneously; but the moment an observer steps in, which in this case is the screen, why doesn’t the wave collapse? We know that it doesn’t; so how can we conclude that an observer collapses the photon from a wave to a particle? If the screen is not an observer, why does the photon hit at only one point of the screen in case of a single slit or no slit...to hide the which-way info, why doesn't it behave as a wave.

It is apparent that I am missing something basic here. Any inputs will be appreciated.
 
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Yes, the screen is an "observer", or something that is related to an (apparent) wave function collapse. If you want to understand how the apparent collapse may take place without a true collapse, see also about the Bohm interpretation.
 
The how part was never my problem...just the what. Also, I am aware of Bohm's interpretation. Anyways, thanks for the response!
 

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