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Do particles exist forever? Can Anything Exist forever?

  1. May 9, 2006 #1
    Can any particles last forever? Is that all particles will eventually decays? And is that after decay, in another process they will form back again?
     
  2. jcsd
  3. May 9, 2006 #2

    Mk

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    If you had a neutron, well, it most probably end up decaying into other particles, and that would mean that it didn't last forever. Of course conservation laws are still in place.
     
  4. May 10, 2006 #3

    Kurdt

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    neutrons have a half life of approximately fifteen minutes and then they decay into a proton. protons and electrons seem to be the most stable particles and their half life is in texts as being infinite but of course they could just have an extremely long half life of greater than the present age of the universe.
     
  5. May 10, 2006 #4

    mathman

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    Grand unified theories seem to require proton decay. However, all experiments to date have come up with a half life something > 1033 years, i.e. no decays observed.
     
  6. May 10, 2006 #5
    Does this mean that currently no evidence that GUT is correct?
     
  7. May 10, 2006 #6

    Mk

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    We don't have any grand unified theories yet, ones presented have been full of errors, anomolies, etc, but there are some still in production.
     
  8. May 11, 2006 #7
    photons do not decay as they experience no time
     
  9. May 11, 2006 #8

    Time?
    "Decay" pre-supposes that there are fundamental particles associated with the original.
    Hence, photons do not decay because there is nothing to "decay".
    In addition, a photon, though it can exhibit particle-like behavior, is not a particle. It is a force carrier.
    My perception(though I could be wrong) is that force-carriers cannot decay, having nothing to do with "time"
     
  10. May 12, 2006 #9
    Can I chip in to say there is something of a conceptual problem with "particles". We tend to think of them as little billiard balls, but it might be better to think of them as regions of spacetime with certain properties. As I'm sure Flatland will concur, there's also a conceptual problem with Forces being thought of as messenger particles rather than distortions of spacetime in one or more dimensions. It gets worse when you look at time, because in a way the time is in the "particle" rather than the particle being in the time. All these issues fog the original question, and maybe it should be rephrased to How and why does a region of spacetime make a quantum-leap state change to break into one or more regions of spacetime with different properties? But I don't know the answer to that. Sorry.
     
  11. Jul 10, 2008 #10
    I would think that ultimately everything material decays (perhaps even protons and electrons and neutrino's) and in theory could lead to a universe which only contains radiation (Penrose has speculated about this idea, and suggested that in that instance the universe forgets about time and the universe will re-inflate and forms a new big bang, see http://www.newton.ac.uk/webseminars/pg+ws/2005/gmr/gmrw04/1107/penrose/) but then the universe in one or other form will always exist.
    If we assume that matter+energy is conserved always, there will always be a universe, and we do not currently doubt this.
     
  12. Jul 10, 2008 #11
    I would argue that this is because of having no rest mass.
     
  13. Jul 14, 2008 #12
    Why do neutrons decay so readily when not confined in an atomic nucleus?
    Does strong nuclear force help prevent their rapid decay?
     
  14. Jul 14, 2008 #13

    malawi_glenn

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    You can naively think of this as the neutron inside a nucleus has lower mass then a free neutron due to the binding energy, which precents the proton to become an accessible decay state for the neutron.

    (http://en.wikipedia.org/wiki/Beta_decay )
     
  15. Jul 14, 2008 #14

    neu

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    What would the proton decay to?
     
  16. Jul 14, 2008 #15

    mathman

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    Although some theories predict proton decay, there has been no evidence of it. If it does the half life is > 1033 years.
     
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