Reflection and the measurement, and time irreversibility

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SUMMARY

The discussion centers on the concept of reflection in quantum mechanics, specifically addressing its nature as a time-reversible process rather than a measurement. It highlights that reflection does not erase coherence, such as interference patterns. The conversation also explores the implications of measuring the momentum of a photon and its effect on a mirror's rotation in a vacuum, raising questions about the relationship between measurement and interference patterns in quantum experiments.

PREREQUISITES
  • Quantum mechanics fundamentals
  • Understanding of interference patterns
  • Concept of momentum in photons
  • Basics of experimental setups in vacuum conditions
NEXT STEPS
  • Research the principles of quantum measurement theory
  • Explore the effects of photon momentum on macroscopic objects
  • Study the implications of time-reversibility in quantum mechanics
  • Investigate experimental designs involving mirrors and interference patterns
USEFUL FOR

Physicists, quantum mechanics students, and researchers interested in the nuances of measurement and interference in quantum experiments.

Dmitry67
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Reflection is not considered to be a measurement. Reflection, like using lenses is considered to be a time-reversible process. It is not a measurement and it does not erase the coherence (interference pattern)

Here is what I don't understand

What happens to the momentum of the photon? The light pressure? If I put a mirror (flying in a zero gravity and vacuum) right behind 2 slits, mirror will start rotating very slowly in a different directions depending on the path of the photon

Where is a flaw?
 
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If you can measure the mirror's momentum well enough to detect which slit the photon went through, the posistion will be uncertain enough to destroy the interference pattern.
 
My mirror is flying in the empty space. If it is hit by 1 photon, it begins to rotate making 1 full rotation per 1 year. So I make an experiment and decide to check the position of a mirror 3 month later. What is going to happen to the interference pattern?
 

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