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Homework Help: How does the universe end? Show the final equation.

  1. Aug 8, 2008 #1
    1. The problem statement, all variables and given/known data

    You are now familiar with the relationship between enthalpy, entropy, free energy and work. How does the universe end? Show the final equation.

    2. Relevant equations

    The only thing I can think of that might be relevant is

    [tex]\Delta G^{\circ}= \Delta H^{\circ} \ - \ T \Delta S^{\circ}[/tex]

    3. The attempt at a solution

    I don't really know where to start. My problem lies in the fact that I'm not sure exactly what the question entails.

    What state would signify "the end of the universe" to be exact?

    Any ideas?

  2. jcsd
  3. Aug 10, 2008 #2
    Does the lack of response mean everybody else is also stumped?

  4. Aug 10, 2008 #3


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    … quick! … just got time! …

    Hi phyzmatix! :smile:

    Well, if the universe is ending, we can't be bothered to answer! :wink:

    :smile: but maybe it isn't … so … :smile:

    I'll guess they're asking for the limiting value, as time tends to infinity, of energy (or entropy or …) per unit volume. :smile:

    … gotta go … ! :smile:
  5. Aug 10, 2008 #4


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    I suspect the question is asking about "heat death". Since the entropy is always increasing, your equation says that, eventually, there will be no free energy- all motion will be randomize, the temperature will be constant throughout the universe and so no work can be done.
  6. Aug 10, 2008 #5


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    I would go with the second law of thermodynamics as the equation describing the end of the universe:

    [tex]\Delta S_{universe} \geq 0[/tex]
  7. Aug 10, 2008 #6
    My initial thought was that it must be a state of zero free energy and it seems like you tend towards the same conclusion. Since the equation I quoted above isn't necessarily a MUST use, I'll play around with the ideas you've given me and sit on it a while longer. See what I can reference from my textbooks.

    Thanks everyone for your input :smile:

    (PS Tiny-Tim, if the universe comes to an end any time soon, I'll be PISSED!!! :grumpy: :rofl:)
  8. Aug 10, 2008 #7


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    :biggrin: I'll get the beers in! :biggrin:
  9. Aug 11, 2008 #8
  10. Aug 11, 2008 #9


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    "From nothing
    it came;
    to nothing,
    shall it return".

    I thought everyone knew that. Scientists may one day be surprised how close the relationship is between the nothing and the infinite. IMHO.
  11. Aug 11, 2008 #10


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    nothing …

    There's no such thing as a free quark! :wink:
  12. Aug 12, 2008 #11
    How would you put that into an equation format involving the above-mentioned concepts of entropy, enthalpy etc?

  13. Sep 9, 2008 #12


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    I would not have answered this question any other day, but by coincidence according to some people the universe could end today due to an experiment due to happen at CERN Geneva. I cannot be sure therefore that you will see this. 24 h from now to be sure the universe has not ended check if there is a CERN press release confirming it, as that sort of thing is not widely reported in the ordinary papers because it does not sell copies.
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