Photons are produced at random?

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    Photons produced Random
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Discussion Overview

The discussion revolves around the behavior of photons emitted from a hydrogen atom after it absorbs an incident photon. Participants explore whether the direction of the emitted photon is random or correlated with the direction of the incident photon, considering concepts such as coherence and conservation of momentum.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions whether the direction of the emitted photon is random or correlated with the incident photon's direction.
  • Another participant suggests that conservation of momentum could provide insight into the directionality of the emitted photon.
  • A different viewpoint introduces the concepts of coherent and incoherent processes, indicating that if there is a correlation, it is a coherent process, while a lack of correlation indicates an incoherent process.
  • One participant reflects on the implications of absorption spectra and questions whether certain absorption lines are prohibited by the mechanism of photon emission and directionality.

Areas of Agreement / Disagreement

Participants express differing views on the correlation between the directions of the incident and emitted photons, with some suggesting coherence and others leaning towards incoherence. The discussion remains unresolved regarding the implications for absorption spectra.

Contextual Notes

Participants note the importance of conservation of momentum and the distinction between coherent and incoherent processes, but there are unresolved assumptions regarding the nature of absorption spectra and the mechanisms involved.

Chaos' lil bro Order
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Consider a hydrogen atom. A photon strikes it at some random angle. The hyrogen's electron absorbs the photon. The electron becomes excited and its orbital increases. The electron deexcites and emits a photon.

Question: Is the direction of the emitted photon a random direction. Or is there a correlation with the emitted photon's direction with the original incident photon's direction?
 
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Chaos' lil bro Order said:
Is the direction of the emitted photon a random direction?
You can answer your own question if you consider conservation of momentum. (A photon of energy E has momentum |p| = E/c.)
 
Chaos' lil bro Order said:
Question: Is the direction of the emitted photon a random direction. Or is there a correlation with the emitted photon's direction with the original incident photon's direction?

Both can occur. It if there is a correlation, we talk about a coherent process, if not, we talk about an incoherent process. Usually the "absorption-re-emission" process is incoherent.
 
DrGreg said:
You can answer your own question if you consider conservation of momentum.

That seemed reasonable at first (I can see through water), but then I started thinking about absorption spectra. If I hit a sample with photons of an appropriate energy to excite the atoms, and assume the atom will emit the exact same frequency, then obviously in the atom's rest frame it cannot have altered the photon's direction. But without scattering, I shouldn't be able to measure absorption spectra.

Is this actually a mechanism that prohibits certain absorption lines, or was my assumption wrong?
 

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