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A layman's question about Thermodynamics (End of the universe)

  1. Jun 22, 2014 #1
    I am little experience of physics so please be patience with me, This is my first post of this great internet forum.

    I have a friend who said that energy will never remove from the universe only transform (e.g. cogs loses energy from friction that´s turn into radiation).

    But if that true how come the universe will end? What´s the name of the theory about the end of the universe?

    if energy is constant universe wouldn't universe live forever?

    thanks for your time best regards Conny. :)
  2. jcsd
  3. Jun 22, 2014 #2


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    This is simply the first law of thermodynamics: energy may be transformed, but the total amount doesn't change.

    The universe is expanding - so the energy is thinning out in each region: the density is decreasing. So if you wait long enough there won't be anything left but a thin "gas" of ever weaker photons - the cosmic background radiation plus any additions from stars, etc - and at some point you might say that "this is no longer interesting - nothing going on here!

    At that point you might say "the universe has come to an end".

    There are various cosmic theories; you might enjoy Stephan Hawking's "A Brief History of Time".

    PS: Welcome to PF!
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