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This universe & entropy

  1. Mar 9, 2010 #1
    If this universe can be said to have started as supremely low entropic, and entropy can be said to always increase in an isolated system, then isn't it possible to make certain deductions (or more accurately, speculations) about whatever the superset reality is, beit physical or otherwise, and the nature of this reality in regards to its properties?

    Also, do you think that it can be safely assumed that entropy exists in the super-system (if such a reality exists), simply by our observations of it in the sub-system?
  2. jcsd
  3. Mar 9, 2010 #2


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    These are good questions. And much discussed of course.

    There are a number of quite different ways of answering the question. I will mention the approaches I favour.

    A key question to focus on is whether we can think of the universe as a closed or open system.

    You might argue that the universe winked into being out of nothing (perhaps a quantum "nothingness") and so it is an isolate system. There is no need for entropy outside as there is no outside. The same goes for a cyclic universe model where re-collapse somehow recreates the intial low entropy condition.

    But instead, a different model would be to think of the universe as a dissipative structure, an entropy degrader. So it would be something that arises by disposing of a greater gradient "outside" itself - just like a cell or dust devil is an orderly structure that arises by the disposal of entropy.

    You have to ask how does an expanding universe fit into the standard closed system approach. A universe that was static, could not cool. The fact that the universe expands (and so creates a heat sink within itself) is what allows the disposal of entropy.

    So thinking about this, we in fact have a hybrid answer suggesting itself.

    The universe is a closed, and even properly isolated, system of some kind. From the evidence of the big bang (excluding dark energy perhaps), all its "contents" in the form of heat/light/energy fields were there from the start. The first law of conservation applies. But it is also an open system in that it expands and is making a giant heat sink, in effect transporting all that energy density "bitten off" at the big bang moment across the boundary of a structure (the structure of an expanding, cooling, spacetime of certain dimensional symmetries) and creating a vast internal heat sink.

    The normal open system transports (n)egentropy from a source on one side to a sink on the other (like a boiling pot with a flame to one side, colder air to the other). But the universe is not moving anything outside, just spreading it around to create an inside.

    So entropy concepts can be applied. But we have to then think more radically about the kind of structure that is doing the entropification.

    Is it a closed system? Is it an open system? Or is it something that combines aspects of both in a way we are not used to thinking of things.
  4. Mar 9, 2010 #3
    Thankyou for your well informed reply.

    How does this make it an open system? Wouldn't the universe still be an entropically closed system - causally isolated from whatever other realitie(s) exist, even if this was the case?

    Wait, that question ^ was a bit premature since we don't know the exact mechanics of the wavefunction collapse.
    Last edited: Mar 9, 2010
  5. Mar 9, 2010 #4
    Whats a superset reality? I'm not really following all the sub/super worlds thingy could you explain what you mean a bit more?
  6. Mar 9, 2010 #5
    A reality that either preceeds this one, or is causally responsible for this reality.
  7. Mar 9, 2010 #6
    What would that look like? The idea seems a bit different to me.
  8. Mar 9, 2010 #7
    It wouldn't "look" like anything. All I was asking in my OP was, IF some reality existed separate to our supposedly closed physical universe, would we be safe in making any logical inferences about this reality given the laws of thermodynamics and this universe's low entropy start.
  9. Mar 9, 2010 #8
    What makes you so sure there is a reality separate to ours? I guess to answer your question it most likely would be true that our physical state reflects that reality "above" us. However how it does so would be hard to know without actually knowing what you mean by separate reality exactly.
  10. Mar 9, 2010 #9
    I'm sorry, that was a horrible choice of wording that didn't reflect what I actually meant to say. I don't mean a separate reality, I meant one that either preceeded this one or caused it to come into existence (in the case that this universe isn't a lone fluke, or if this universe isn't cyclic, i.e. big crunch --> big bang forever)
    Last edited: Mar 9, 2010
  11. Mar 9, 2010 #10
    Well I believe the current held theorys on if information can be found as to what came before this universe is that we really can't know and that all information would have been lost if there was a universe before ours. However I think by looking at the state of the universe now we can infact figure out what it might have been like in the past. So again my answer is yes we can figure out what was before at least to some extent.
  12. Mar 10, 2010 #11


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    It is open in that the universe is being seen as arising upon some greater entropy gradient. And it is closed in that the system finds a way to internalise its waste. And in the way which all its materials are pinched off at the initial big bang instant.

    So it combines features of both open and closed models. It is a closed but expanding. The difference is that it does then make it natural to talk about the kind of greater realm from which the universe might arise as a dissipative structure.

    Really, this is the kind of thinking that was behind Linde's chaotic inflation theory.


    Not that I think his approach works, but it is the kind of approach I am talking about in general.

    Well, it would also be a solution to that if what the universe is dissipating is quantum indeterminancy. A decoherence approach in other words.

    Of course, to see this, you have to start to move away from the idea of negentropy (low entropy/high energy) as "order". Instead, your initial conditions would be defined in terms of greater symmetry - which could thus give something "orderly" to be broken.

    Again like Linde's scalar inflaton field. But again, an infinite exponentially expanding energy field is too concrete a notion to really fly.
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