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Infinite Gravity

  1. Jan 29, 2006 #1
    How can photons be particles if they have no mass? Are they just a concept so that light can be rationalized, or do they really exist? Please pardon my ignorance, as I am still relatively young (15.)
  2. jcsd
  3. Jan 29, 2006 #2
    Ange, photons are tiny bits of pure energy. Sometimes they act like waves, and sometimes they act like particles. Yes, they really exist but a complete description can be very complicated.
  4. Jan 29, 2006 #3
    Can energy be converted into matter? If so, then couldn't we convert photons into matter?
  5. Jan 29, 2006 #4
    And if we could convert energy into matter, could it happen the other way around?
  6. Jan 29, 2006 #5
    As far as I know, matter can be converted into energy, but energy can only be converted into matter in extremely small subatomic amounts using particle accelerators that cannot be assembled to form atoms, molecules, etc. because of conservation laws of energy. Am I right?
  7. Jan 29, 2006 #6
    Energy can be converted into matter. At the Stanford Linear Accelerator Center (S.L.A.C.), they used high powered lasers and electromagnetic fields to turn light into a tiny amount of matter, as you said, about particle size.
    Last edited: Jan 29, 2006
  8. Jan 29, 2006 #7
    Yes, but as I said above, the particles that result from this are even smaller than atoms. The reason they cannot form the kind of matter we are familiar with is described above. Usually, when particle accelerators are used, matter and antimatter pairs are created, which have the unfortunate tendency to unite and form energy again. Antimatter has been seperated from matter using magnetic fields before, but this is difficult.
    Last edited: Jan 29, 2006
  9. Jan 29, 2006 #8


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    Basically, what you mean by "particle" is probably what we call the classical notion of a particle. That concept is fine and good for classical approximations, but it breaks down at extreme scales.

    A photon is not a classical particle.

    However, we now have a quantum mechanical notion of particle which generalizes (and "fixes") the old notion of a classical particle. A photion is this sort of particle.

    You don't actually have to get to quantum mechanical levels for this to be useful -- I believe that things like solitons and phonons are essentially the same idea, and they behave at the classical level.
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