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

Can we accurately measure the momentum of a particle?

  1. Feb 21, 2015 #1
    Is there any law that prevents us from accurately measuring the momentum of a particle , just like the energy time uncertainty principle makes us observe the system for an infinite amount of time before we can be certain about its energy? I got this doubt because if we can do it, we will collapse the wave function into the eigenstate of momentum, which is not a normalisable state. I know that practically, measurements always come with some uncertainty, but at least in theory can we do it?
     
  2. jcsd
  3. Feb 21, 2015 #2

    mfb

    User Avatar
    2016 Award

    Staff: Mentor

    If you have enough time, the measurement can get as precise as you like (in theory). Just set up a detector light years away and measure when and where the particle arrives.
     
  4. Feb 21, 2015 #3
    Reminds me of the energy time uncertainty Principle. So is this true of all observables? And is there any formula that tells to what accuracy we can measure the observable given the amount of time we observe it?
     
  5. Feb 21, 2015 #4

    mfb

    User Avatar
    2016 Award

    Staff: Mentor

    That is not an accident as momentum and energy are related - measure one precisely and you get the other precisely. I guess you can use the energy/momentum relationship to set a lower bound on the measurement time.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Can we accurately measure the momentum of a particle?
Loading...