What is the Default Speed of an Electron in a Vacuum?

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Discussion Overview

The discussion revolves around the concept of the default speed of an electron in a vacuum, exploring whether there is a universally accepted speed for electrons and how their speed is influenced by various factors, including observer reference frames and energy levels. The conversation touches on theoretical implications and interpretations of quantum mechanics.

Discussion Character

  • Conceptual clarification
  • Debate/contested
  • Exploratory

Main Points Raised

  • Some participants question the notion of a default speed for an electron, suggesting that speed is relative to the observer's frame of reference.
  • One participant notes that an electron can theoretically have zero speed, but this raises questions about the implications of the Heisenberg uncertainty principle on its position and velocity.
  • Another participant mentions an experiment where an electron was stored in a magnetic trap, highlighting that its speed can vary significantly depending on the conditions, such as being accelerated to speeds close to that of light in particle accelerators.
  • There is a suggestion that the expectation value for velocity can be zero, indicating a nuanced understanding of quantum mechanics.
  • Some participants argue that light is the only entity with a fixed speed across all reference frames, implying that there is no single speed that all electrons must adhere to.

Areas of Agreement / Disagreement

Participants express differing views on the concept of an electron's speed, with no consensus on whether a default speed exists. The discussion remains unresolved, with multiple competing interpretations of the electron's behavior in relation to speed and reference frames.

Contextual Notes

The discussion involves complex interpretations of quantum mechanics, including the effects of the Heisenberg uncertainty principle and the relativity of speed based on observer frames. These factors contribute to the lack of a definitive answer regarding the default speed of an electron.

physx_420
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This isn't a homework question but if it belongs in another thread please tell me so I can switch it.

I was just wondering if there is an "agreed-upon" speed that an electron would travel in say a vacuum? I understand that one can continue adding energy until the electron reaches very nearly the speed of light, but how fast does it go to begin with? Sorry in advanced if this is somewhat trivial.
 
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A speed relative to what?
 
hi physx_420! :wink:

an electron can have zero speed

as Dr Lots-o'watts says, its speed depends on the frame of the observer :smile:
 
A group at the University of Washington had a single electron stored in a magnetic trap (in vacuum) for about 6 months, but one morning they looked for it and it wasn't there. How fast is that?

CERN in Switzerland built an accelerator that accelerated electrons to about 50 billion electron volts (in vacuum), which is about 0.999999999 times the speed of light.

Bob S
 
tiny-tim said:
hi physx_420! :wink:

an electron can have zero speed

Can it really? Electrons, like everything else, are subject to the Heisenberg uncertainty principle. If it's velocity is zero then it's position would be infinitely uncertain, it would have an equal probability of being anywhere in an infinite universe. I don't believe the universe is infinite to its velocity cannot be zero. It can be uncertain within a range that includes zero, but that is a different thing.
 
The expectation value for velocity can nonetheless be zero.
 
Light is the only thing that has a fixed speed relative to all reference frames so, as others said, the question doesn't make sense. There is NO one speed all electrons must have.
 

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