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Predicted Heat Death of the Universe

  1. Jul 24, 2015 #1
    Predicted Heat Death of the Universe

    In his thought provoking documentary “Wonder of the universe” (

    ) Professor Brian Cox explains the thinking behind current predictions for the “Heat death of the universe”. He explains the predictions through the effect of the second law of thermodynamics whereby the universe gradually moves from an ordered state (low entropy) to a state of disorder (high entropy). He states:

    The last remaining matter in the universe will reside within black dwarves. We can predict how they will end their days. The last matter of the universe will evaporate away and be carried off into the void as radiation leaving absolutely nothing behind.

    There won’t be a single atom left; all that’s left will be particles of light and black holes. After an unimaginable period even the black holes will have evaporated; the universe will be nothing but a sea of photons gradually tending to the same temperature as the expansion of the universe cools them towards absolute zero.

    The story of the universe will come to an end. For the first time in its life the universe will be permanent and unchanging. Entropy will finally stop increasing because the cosmos cannot get any more disordered. Nothing happens and it keeps not happening for ever. There is no difference between past present and future, nothing changes, arrow of time has simply ceased to exist.

    It is an inescapable fact written into the laws of physics that entire cosmos will die; all the stars will go out extinguishing possibility of life in the universe.”

    Reconciling the predicted Heat Death of the Universe with the initial state

    The assumption seems to be that the singularity from which the universe is thought to have arisen was an ordered state (low entropy) and that since the big bang the entropy is increasing with the inevitable end result that all matter will be converted to energy which will then cool to absolute zero after which entropy will be at its maximum value and nothing will occur in the universe.

    The predictions appear to be correct according to the second law of thermodynamics. One can imagine an ever expanding universe whereby all its heat energy is dissipated until it reaches absolute zero temperature whereupon all events will cease.

    There are fundamental difficulties in accepting this end state of the universe.

    Firstly it is extremely depressing and counter intuitive for humans to envisage a universe in which there is no possibility of life and where no events will ever occur. However this difficulty does not preclude such an end state of the universe.

    The second and more important difficulty in accepting this end state is in reconciling the predicted end state of the universe with the currently accepted initial conditions of the universe prior to the big bang.

    The initial conditions of the universe prior to the big bang are assumed to be a singularity of infinite density and zero volume which according to the second law of thermodynamics would be considered to be a highly ordered state with low entropy. The question arises as to how the singularity came to be in this state and what caused it to suddenly expand so rapidly into the observable universe.

    The singularity can only have been in existence for a finite period of time as otherwise it could not have suddenly expanded.

    As in the predicted end state of the universe at a temperature of absolute zero no events can occur without events to precipitate such events.

    Assuming the singularity to be an enclosed system with nothing outside (no space, no matter, no energy, no events) the expansion can only have occurred as a result of events within the singularity. Alternatively assuming no events inside the singularity the expansion can only have occurred as a result of events outside the singularity.

    There is a finite number for all the possible permutations of events that could have precipitated the expansion. It follows that there must have been events prior to the existence of the singularity as a singularity. In other words the singularity must have come into existence from a previous state of its contents.

    Assuming a finite amount of material within the singularity (and the previous states of the singularity) all possible permutations of events including the sequence of events in our current universe constituting the predicted “Heat Death of the universe” would have already occurred prior to the big bang.

    From this it follows that either the predicted “Heat Death of the universe” is not possible or that it is predicated on an incorrect set of data or that the second law of thermodynamics is incomplete.
    Last edited: Jul 24, 2015
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  3. Jul 24, 2015 #2


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    There's also the possibility that your initial assumptions were wrong.

    Like this one:
    In general, the BB singularity is only used as a reference point for measuring time in the early universe (e.g. 'early' means close to the singularity). It is not thought to be an actual physical thing with attributable physical state.
    Have a read through this:
    especially this bit:
    'Whether or not there really was a big bang singularity is a totally different question. Most cosmologists would be very surprised if it turned out that our universe really did have an infinitely dense, infinitely hot, infinitely curved beginning. Commonly, the fact that a model predicts infinite values for some physical quantity indicates that the model is too simple and fails to include some crucial aspect of the real world.'

    Or this one:
    In the heat death the end temperature is non-zero, and that allows quantum fluctuations to occur. John Baez has a nice write-up on this subject:
  4. Jul 24, 2015 #3
    Thank you for your comment. Both articles you posted are very interesting but do not impact on my initial assumptions which are predicated on the evidence of state of the universe prior to the rapid expansion which I would agree is more likely to have been an extremely compact dense, hot universe rather than a singularity. Even if the evidence supporting the big bang is ultimately interpreted in an entirely different way it will always lead to some state of the universe 14 billion years ago. Whatever state that was (assuming a finite quantity of matter, energy and space and assuming mathematics is a reliable tool) must have arisen from a finite number of all possible permutations of events including the sequence of events in our current universe constituting the predicted “Heat Death of the universe”.

    My general point here is that the stuff of the universe cannot have come into existence from nothing (in the literal sense). It follows mathematically that any possible future state of the universe must already have been played out. It follows that no future state of the universe can be a final state of maximum entropy where events cease to occur.
  5. Jul 24, 2015 #4


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    I agree with you, but this is utterly irrelevant to science
    Right. So why bring it up? There are lots of things in cosmology (the very large) and quantum mechanics (the very small) that are not even remotely "intuitive" for humans.
    since, as has already been pointed out, "singularity" just means the place where our math model breaks down and give unphysical results, your conclusion here does not follow.
    There is no reason at all to assume a finite amount of material "within the singularity (and the previous states of the singularity)" so this conclusion doesn't follow either.

    Do you have any references for this assertion? It does not agree with the beliefs of some respected physicists.
    Again, your "it follows" is predicated on false, or unproven, assumptions.

    I am not agreeing or disagreeing with your conclusions so much as I am attempting to help you see that conclusions need to be based on a firmer foundation than what you have.
  6. Jul 24, 2015 #5
    There is something wrong here, first, it's not an assumption that the past was more ordered than now, it's a definition. You may be confused by what the physics meaning of "ordered" is, it's not the same a "structured" or "interesting order" it's just a state.

    Heat death is not an inevitability, it's a mathematical prediction of the current formulation for how the universe works. It's one of many possible outcomes, others include the polar opposite, a hot fiery collapse, others predict the universe will just change into something else. Personally, I like that one better, but without any evidence, no one can say.
  7. Jul 25, 2015 #6
    Imagine cosmologists in the distant future observing a universe empty except for the locally gravitationally bound Milky Way, Andromeda, and their associated smaller structures.

    In one case, the entire evolution of the cosmologists' star system, planet, life, and emergence of the cosmologists as thinking beings will have occurred well after the universe was emptied, so they might have no evidence that it once was not so.

    In another case, the cosmologists represent a fortunate life form that originated during the non-empty state of the universe but made it well into the empty state.

    In both cases, observations of an empty universe will have been consistent for a long time...

    Those that arrived in the already empty universe might assume it had always been empty and consisted of just the local stuff (whatever becomes of the Milky Way and Andromeda). Those that arrived before the non-empty state but now long after are living in the empty state might not believe the ancient myths (from very long ago) describing an expanding universe full of structures.

    We might be living in a special time that allows us to observe the universe before it empties out... if you were a future cosmologist observing an empty universe, one that seemed to have been that way for a very long time, what would it take to convince you that it had once been full of structure, and expanding, or even had a beginning, etc...?
  8. Jul 25, 2015 #7


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    A universe from 'nothing' remains a viable option under quantum theory. Liking it is optional. QM does not play well with human logic.
  9. Jul 30, 2015 #8
    What do you mean by a "definition"? Do you mean that this is proven to be factually correct?
  10. Jul 30, 2015 #9
    What experimental evidence do you draw on to conclude that under quantum theory something can appear from nothing?
  11. Jul 30, 2015 #10


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    Virtual particles that may have been demonstrated experimentally by the casimir effect. (if not the van de Waals force)

  12. Jul 30, 2015 #11
    The experiments took place in a real three dimensional space containing matter, anti matter, virtual particles and a gravitational field. It follows that the effect measured cannot be deemed to have arisen from nothing.
  13. Jul 30, 2015 #12


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    True, but how do you propose to arrange a falsifiable experiment in absolutely nothing.

  14. Jul 30, 2015 #13
    Well that's of course not possible. The important point here though is that in any such experiment where a particle or force (or both) has apparently arisen from nothing it is more probable that there is a rational explanation to be found based on known physics (or yet to be known physics), mathematics and human reasoning.

    There is much in physics that is observed and measured quantitatively that is not understood qualitatively such as any of the known forces. For example how can 1 particle of matter influence another particle in a remote location to move towards it with only empty space in between? Of course it may not be possible to find any mechanical analogy to explain such phenomena but in my view it will eventually be understood.
  15. Jul 30, 2015 #14


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    As Chronos said; "under quantum theory. Liking it is optional. QM does not play well with human logic."

    Not only is 'liking it' optional but 'understanding it' as well, the theory makes predictions that have not yet been falsified so it stands as the best description of what goes on.

  16. Jul 31, 2015 #15

    A probabilistic theory of the state of the currently observable universe prior to the big bang


    Prior to the big bang all the matter and energy in the currently observable universe was contained within a singularity tending towards infinite density and infinitesimal volume.

    The singularity expanded rapidly giving rise to the currently observable universe.

    The singularity expanded rapidly due to events within the singularity.


    M = the number of discrete items (matter or energy or any other possible physical entity) present within the singularity.

    The number of possible events P between discrete items within the singularity is given as:

    P = M2 (M to the power of 2)

    P is a FINITE value for all FINITE values of M

    I = the number of actual events between discrete items within the singularity prior to the rapid expansion.

    On the assumption that the rapid expansion did occur it follows that I is a FINITE number.


    It follows subject to the assumptions that there was a prior state to the singularity that gave rise to the currently observable universe.
  17. Jul 31, 2015 #16


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    If you start with made up assumptions you can conclude anything you like.
  18. Jul 31, 2015 #17


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    Disappointing to see Cox spreading a common misconception like this. See Adams and Laughlin, http://arxiv.org/abs/astro-ph/9701131 , §VD. The matter fields in the distant future (as opposed to dark energy) are actually dominated by massive particles, not photons, for the same reason thatthe universe went from radiation-dominated to matter-dominated at t~10^9 yr. The main forms of matter are expected to be dark matter, neutrinos, and electrons and positrons that exist within their own cosmological horizons so that they can't annihilate.
  19. Jul 31, 2015 #18
    are these assumptions not commonly held within the scientific community?
  20. Aug 1, 2015 #19


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    Since this thread has become pure personal speculation, it is closed.
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