Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Accelerating electrons

  1. Apr 26, 2008 #1
    I was always interested why have scientists tried to speed up electrons to the speed of light, unless they were trying to disprove the absolutness of speed of light itself, which highly unlikely was their intention.

    I mean, when electromagnetic device is used to speed the electron then photons are the mediators, right? Since photons move at c then I suppose it is natural to expect that as electron approach the speed of light it will be harder and harder to accelerate it further.

    My question is: Does indeed anything happen with the electron mass at high speeds, or is it just a convenient explanation of reduced ability to speed up electrons close to (or beyond?!?) the speed of the mediators?
  2. jcsd
  3. Apr 26, 2008 #2
    There are lots of reasons to speed up electrons (and other particles) to relativistic speeds. Its quite well agreed that the speed of light, really is (unfortunately) the maximum, and i don't think many people are still trying to disprove that.

    As the electrons speed up, they become significantly more massive (this has been measured / confirmed). As they approach the speed of light, they become infinitely massive, and would require an infinite amount of force (and energy) to accelerate it further -> hence they cannot pass the speed of light.

    You're argument about E&M being mediated by photons is an interesting and good one, but because of special relativity, from the electron's reference frame, the photons are still going the speed of light faster than it, and still successfully mediate the applied forces.

    Does that answer your question?
  4. Apr 27, 2008 #3
    Electrons cant speed up to the speed of light,acording to relativity theory their mass will approach infinity which is impossible,As the rest mass of electron is not zero.ALSO INFINITE FORCE IS REQUIRED TO ACCELERATE SOMETHING HAVING INFINITE MASS.
    Rashid Iqbal
    Physics Teacher
  5. Apr 27, 2008 #4


    User Avatar

    Staff: Mentor

    Even though the electrons can't go faster than the speed of light, we can still make their energy as large as we want (or at least, as large as we have the resources to do so). High-energy electrons are a useful tool for probing the structure of matter, by studying how they scatter off other things.
  6. Apr 27, 2008 #5
    Thank you all for your answers.

    As you probably noticed I am only beginner... That's probably why I forgot to take into account the electron's reference frame when thinking about photons. Thanks lzkelley. ;-)

    How exactly is the increased electron mass measured?

    Does this increased mass has any gravitational effect?

    Also, how is the speed of the accelerated electron measured?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook