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

Feynman's perspective on negative energy states and pair creation

  1. Jul 5, 2008 #1
    Dirac's theory of the electron predicted that there were identical particles of equal mass but of negative energy.

    He appealed to the Pauli exclusion principle and proposed that there was a negative energy 'sea' of electrons that was full up to -2mc^2 in order to answer critics that positive energy electrons described by the Dirac electron theory would simply decay down to -infinity.
    With this description pair creation is described by absortion of a photon (where the energy of the photon E_p > 2mc^2) by a negative energy electron that scatters up to a poitive energy state leaving behind a hole.

    This hole is the negative energy 'sea' has equal but opposite charge to the electron and is commonly known as a positron.

    I believe that this description is somewhat old hat and not used anymore in modern QFT circles. Can anybody give me a not too technical explanation to why the 'old hat' qualitative explanation is unsatisfactory and how Feynman's resolution works, i.e. negative-energy particles can only travel backward in time.
  2. jcsd
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted