Electrons at the speed of light?

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Discussion Overview

The discussion centers around the behavior of electrons when accelerated to speeds approaching that of light, particularly in the context of collisions with positrons. Participants explore theoretical implications of such high-speed interactions, including mass-energy conversion during collisions.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • One participant questions whether an electron can reach the speed of light before colliding with a positron, and if so, whether it would convert to energy before the collision.
  • Another participant asserts that no particle, including electrons, can reach the speed of light, noting that they can only be accelerated to speeds very close to it.
  • A participant seeks clarification on the timing of mass-energy conversion during a high-speed collision between an electron and positron, questioning whether it occurs at the moment of collision or beforehand.
  • Further elaboration is provided on the nature of "collision," suggesting that a free electron may be considered a point source, which complicates the idea of a direct collision with its antiparticle.
  • One participant speculates on the timing of mass-energy conversion, comparing it to the emission of a photon during an electron transition in an atom, though they express uncertainty about the validity of this analogy.

Areas of Agreement / Disagreement

Participants express differing views on whether electrons can reach the speed of light and the nature of collisions with positrons. There is no consensus on the timing of mass-energy conversion during these interactions.

Contextual Notes

The discussion includes assumptions about the nature of particles and interactions, as well as the implications of relativistic speeds. The definitions of "collision" and "just before" are not universally agreed upon, leading to further complexity in the discussion.

rcgldr
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If linear accelerator were to accelerate an electron very close to the speed of light towards a positron source, (or if the speed in a circular type accelerator with both electrons and positrons circling in opposite directions) could the electron reach the speed of light before collision with the positron? If so, does the electron turn into energy before collision?
 
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No particle (other than a select few) can reach the speed of light. This includes the electron. They have been acceleated to 0.99c but, not c.
 
Still my question is, in this case, a very high speed collision between an electron and positron, does the conversion of mass to energy take place at the time of collision or does it occur just before?
 
Jeff Reid said:
Still my question is, in this case, a very high speed collision between an electron and positron, does the conversion of mass to energy take place at the time of collision or does it occur just before?

What exactly do you mean by a "collision"? And what do you mean by "just before"? Isn't a free electron essentially a point source, meaning it has zero radius when looked at clasically? That would make the probability of a contact collision with it's antiparticle zero. So it must be some interaction with a more extended field, or else we must have its spatial dimension quantized above some lower limit. Similarly for "just before". At .999c, the electron covers a fair bit of distance in a very little time, and there's not much chance to give the positron advance notice of the electron's imminent arrival.

It seems that at the level of detail you're asking about, the answer might be in how long it takes for the conversion to occur. How long does it take a photon to be emitted when a bound electron in an atom transitions between energy levels? I suspect that's how long it would take for the mass-energy conversion to occur in the annihilation, but that's entirely conjecture on my part. I really have no idea if that's on the right track.
 

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