Why can't a photon transfer all its energy to a free electron?

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Discussion Overview

The discussion centers around the question of why a photon cannot transfer all its energy to a free electron. It explores the implications of energy and momentum conservation in such interactions, as well as drawing parallels to classical mechanics.

Discussion Character

  • Technical explanation, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant asserts that it is impossible to conserve both energy and momentum in the process of a photon transferring all its energy to a free electron, suggesting the need for another particle or object.
  • Another participant draws a classical analogy, stating that a ball of mass m cannot transfer all its kinetic energy to another ball of mass M that is not equal to m.
  • A different participant mentions that the only way for a photon to interact with a free electron, aside from high-energy photoproduction, is through Compton scattering.
  • One participant references an external source that purportedly explains the concept well, indicating a search for further clarification.

Areas of Agreement / Disagreement

Participants express differing views on the mechanisms of photon-electron interactions, with some agreeing on the necessity of additional particles for energy and momentum conservation, while others provide analogies and specific interaction types without reaching a consensus.

Contextual Notes

The discussion does not resolve the underlying assumptions about the nature of energy and momentum conservation in photon-electron interactions, nor does it clarify the conditions under which Compton scattering occurs.

ajl1989
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Why is it that a photon can't transfer all its energy to a free electron?
 
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It's imposible to conserve both energy and momentum in such a process. You need another particle or object in order to do this.
 
It's not the same thing, but there is a classical analogue of that fact: a ball of mass m cannot transfer all its kinetic energy to a ball of mass M=/=m.
 
The only way for a photon to interact with a free electron (other than photoproduction at very high energies) is via Compton scattering.
 

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