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

Heisenbergs thought experiment

  1. Mar 26, 2012 #1
    Heisenbergs "thought experiment"

    In two different quantum mechanics books I read about "thought experiments" involving using a microscope to determine the position of an electron, which were both presented as evidence to back up Heisenbergs uncertainty principle. Are there no real experiments that can be done to test the theory? In these thought experiments, microscopes are used to detect the positions of electrons (i.e. adding a light source and a microscope to the double slit apparatus in order to determine which slit the electron comes through) and the problem is that when a photon bounces off the electron, it changes its momentum so while you've now learned the position of the electron, you no longer know its momentum etc. Don't moving charged particles produce electromagnetic fields and thus, radiate energy that could be detected? Or is that only in magnetic fields?
  2. jcsd
  3. Mar 26, 2012 #2


    User Avatar
    Science Advisor
    Homework Helper

  4. Mar 27, 2012 #3
    Re: Heisenbergs "thought experiment"

    The problem with Heisenbergs "thought experiment", and which he used to illustrate his uncertainty principle, is that still too many physicists (not to say about philosophers and others) believe the microscope analogy to be the correct way to explain it. It was Heisenberg's mistake. The complementarity between position and momentum is intrinsic, inherent in the quantum objects, and does not arise due to an interaction of an 'observer' with the object we observe. A misleading analogy that was justifiable at the times of Heisenberg, but it is plain wrong to presented it "as evidence to back up Heisenbergs uncertainty principle" in 2012.
  5. Mar 27, 2012 #4


    User Avatar

    Staff: Mentor

    Re: Heisenbergs "thought experiment"

    I thought I remembered reading somewhere that Heisenberg himself, later in his career, disavowed the "Heisenberg microscope" as an illustration of the uncertainty principle. However, I haven't been able to find a reference or quotation. Has anyone else seen something like this?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook