Optical Interference: Photon Energy Conservation & Vector E

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Discussion Overview

The discussion centers on the concept of optical interference, specifically regarding the conservation of energy in the context of two photons traveling in opposite directions and their interaction. Participants explore whether energy is conserved during destructive interference and the nature of photon energy as it relates to vector quantities.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • One participant questions whether energy is conserved when two photons destructively interfere and whether the energy in E=hf is a vector quantity that considers direction.
  • Another participant argues that a photon should not be considered merely as a part of an electromagnetic wave, suggesting that the discussion is fundamentally a classical electromagnetic question.
  • A participant states that even after destructive interference, the energy remains in the wavepackets, with all energy held in the magnetic field at the point of interference, where the electric field is zero.
  • Another participant seeks clarification on why the electric field is zero at the point of interference.
  • A response indicates that the zero electric field is contingent on the relative phase shifts of the waves, explaining that destructive interference occurs when electric field vectors of equal magnitude point in opposite directions.

Areas of Agreement / Disagreement

Participants express differing views on the nature of photons and the implications of destructive interference on energy conservation. There is no consensus on these points, and the discussion remains unresolved.

Contextual Notes

The discussion involves assumptions about the nature of light as both particles and waves, as well as the conditions under which destructive interference occurs. The dependence on phase shifts and the definitions of energy in this context are also noted but not resolved.

Wishbone
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If you have two photons traveling in opposite directions, that destructivly interfere witheachother, is energy conserverd0? Is the E, in E=hf a vector quantity, that will take in account the directions in which they are travelling? I believe the answer has something to do with treating the light as a particle at that point, and not a wave, however I am not sure. Also, at the point of intersection, is can there be no detection of light?
 
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My first point would be that a photon is not really a bit of an electromagnetic wave. This is essentially a classical EM question, since a classical EM wavepacket carries energy.

Secondly, even if a photon were a bit of an EM wave (I should call it a wavepacket I suppose), after the two wavepackets have destructively interferes, the waves emerge afterwards, still carrying the same energy. In fact, at the point of interference, all the energy is held in the magnetic field and the electric field is zero at that point in space and time.
 
why is the eletric field 0?
 
It precisely depends on the relative phase shifts of the waves at various points. But since you said "destructively interferes" then that's what it means: where the two electric field vectors are pointing in opposite directions but with the same magnitude giving a total of 0 at that precise point.
 

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