I've been thinking about this, and it may sound very ludicrous (and it probably is), but I may have come up with a proto-explanation for it. I hope I won't come across as some misinformed perpetual motion dummy.

Ok, so basically, people are puzzled because of the Universe's highly disordered state shortly after the Big Bang, which was the result of a highly ordered singularity suddenly exploding, resulting in chaos and tons of other material scattering around. Now, this should logically result in high entropy, but on the other hand, the Universe had unusually low entropy at its beginnings.

Could it be that the disorder present at that time was so disordered that it somehow looped back to ordered once again? After all, high entropy is more than just disorder, it is also a sign that the energy present within an enclosed system is also highly degraded and pretty much unusable and impossible to harness. It would make sense for the energy present at the beginning of the Universe to somehow be conserved within the particles scattered by the Big Bang, therefore allowing its harvest and use for the processes that eventually resulted in the Universe as we know it. I don't really know how such a system could be so disordered it eventually resulted in a triumph of order, but I think the high presence of usable, not-degraded, and conserved energy could be the key to that.

Does this sound in any way plausible? You can maul me if it's wrong, and if this problem has already been solved, well, I apologize for wasting your time.

  • $\begingroup$ No need to apologize at all, nobody knows how to explain it. Could I suggest you break up the block of text into a few paragraphs, it's easier to read. Best of luck with it. $\endgroup$ – user108787 Jul 26 '16 at 20:17
  • $\begingroup$ It may help to try to use some equations to capture your concepts of energy and entropy. Singular events such as the Big Bang are notoriously tricky to deal with in terms of entropy, so some mathematical precision may help clarify fuzzy terms like "... somehow it looped back..." One runs into similar issues when exploring the concept of infinity without mathematical precision. The English words can tie one's self up in knots. $\endgroup$ – Cort Ammon Jul 26 '16 at 20:24
  • 1
    $\begingroup$ More on low entropy at Big Bang. $\endgroup$ – Qmechanic Jul 26 '16 at 20:25
  • 1
    $\begingroup$ I won't maul you, but the truth is that this explanation is not even really an explanation, in that it is too vague about what exactly you are suggesting, what the consequences are and how it fits in with the known history of the universe. There is a good reason physics almost exclusively deals with mathematical descriptions of nature- they are our best way of getting around these sorts of vagueness. $\endgroup$ – Rococo Jul 27 '16 at 3:55
  • $\begingroup$ (con't) This isn't to say that you shouldn't keep making these "proto-explanations"- you certainly should- but you should also keep learning about how to express them precisely and explore their consequences. $\endgroup$ – Rococo Jul 27 '16 at 3:55

Well, no, nobody has any idea how it happened.

But personally that sounds kind of nuts. Entropy is not like a Pac-Man game, where if you go off the left side of the screen you pop up on the right. One way to check a theory is to look at its implications. This idea raises all kinds of problems. If (as suggested by Boltzmann, and is behind the Boltzmann's brain problem) the universe started at infinitely high entropy, would it also then be infinitely low entropy? And then is entropy like a giant loop where you are either in the middle or at an extreme? And wouldn't that mess up our normal life? Your idea and it's implications just don't make much sense to me.

People do have a few ideas, though of course, each has their problems. I'll just list the two main ones here:

  1. That our universe is part of a bigger universe at infinitely high entropy, but there are fluctuations from time to time, and we are in one of those fluctuations. This idea was proposed by Boltzmann, and he also gave the Boltzmann curve (see the question Please explain entropy curve). The problem with this is known as Boltzmann's brain...presumably, since the type of fluctuation we are in has such a low probability, the universe we should be in according to probability is the one where a sentient being arises with just enough connections to the outside world to realize it is alive, and then melts back into gloop. Obviously, we are not in that world. Boltzmann did use the anthropic principle in support of this.

  2. The second idea (and I'm just bringing this up because it is an idea, though some would argue it's not very physics focused) is that an all-powerful Creator made it so. I'm not going to go into any objections here, though.

I hope this helps. But honestly, no one knows.

  • 1
    $\begingroup$ Roger Penrose has a book "Cycles of Time" which concentrates on sorting out the low entropy problem (it got mixed reviews "genius to crackpot"). Also, if you look at the comments on this site, because physics is, imo, at the stage of lots of theories but no way of proving any of them, physics itself is increasingly a kind of an emotionally charged issue. $\endgroup$ – user108787 Jul 26 '16 at 22:22
  • $\begingroup$ @count_to_10, physics is a sort of emotionally charged issue, but I thought people would get more upset than normal if I went into the evidence for/against a Creator. The book you recommended sounds interesting...I'll see if I can find it at a library near me. Thanks! $\endgroup$ – heather Jul 26 '16 at 22:38
  • $\begingroup$ Emotionally charged is irrelevant unless you try to use it to force your conclusions. Just leave it out. The sci efficiency method has worked well for a few hundred years, follow it. Combine experiment and theory as before, and let it aort itself out and truth emerge. It is backed by experiments and facts, and some understanding (theory) on how that works. If entropy can't be discussed that way, and measured that way, it means abandon it. $\endgroup$ – Bob Bee Jul 27 '16 at 3:03
  • $\begingroup$ If you're in middle school, how come you know about Pacman? I played Pacman in 1983 as a nineteen year old! $\endgroup$ – Selene Routley Jul 29 '16 at 11:06
  • 1
    $\begingroup$ @WetSavannaAnimalakaRodVance, Pacman is awesome...besides, everyone knows about Pacman. There are enough cultural references to it. And yes, I have played it. =) $\endgroup$ – heather Jul 29 '16 at 11:51

I have found that looking at entropy as defined by statistical mechanics clears up a lot of fluff around the concept. The fact that the underlying level of nature is quantum mechanical , and thus countable, resolves any problems of infinite number of states.

Thus in the current Big Bang model of the universe it is inevitable that entropy will be increasing as the larger the phase space available the more the microstates available.

There is no way I can see your proposal fitting the current model's format.


It is pretty clear for some people that the universe started in a state o low entropy, which would not be that unusual because:

1) the most random way to start a particle and energy distribution is a constant distribution.

2) A constant distribution corresponds to high entropy only if gravity is absent.

3) The state of highest entropy with gravity is a single black hole that has all the matter of the universe inside it.

4) the previous picture does not include dark energy. In the presence of dark energy I am not sure what is the maximum entropy state.

Conclusion, the universe started with low entropy because its mass/energy distribution was random. but due to the presence of gravity this state has very low entropy.

  • $\begingroup$ 1) Why would you set that as the initial condition? Have you measured it? 2) Gravity is not a binding potential for large ensembles of bodies, so the assumption that gravity can produce "lumps" is false. It can only do this in the short term, but the final thermodynamic state, even with gravity included is a homogeneously dispersed state. 3) That contradicts the third law of thermodynamics right there. 4) Possibly nowhere, if energy is not conserved, then the assumption we make in statistical mechanics that the phase space volume is conserved is nonsense. $\endgroup$ – CuriousOne Jul 26 '16 at 23:42
  • $\begingroup$ Hmm... now that I think about it, your answer does make sense, gravity binds the particles together, thereby preserving some order, I didn't really think about that. I did think about what could connect every particle with one another and ensure that entropy is low, but just couldn't exactly pinpoint it. $\endgroup$ – IDontReallyKnow Jul 27 '16 at 0:28
  • $\begingroup$ @IDontReallyKnow: Except that the order due to gravitational interaction doesn't increase, but it decreases, because angular momentum conservation demands that for every mass element that is bound by gravity another mass element has to leave the rest system of the central mass at a higher velocity than it had before. $\endgroup$ – CuriousOne Jul 27 '16 at 0:34
  • $\begingroup$ @CuriousOne Umm.. gravity can produce lumps, otherwise how would stars be able to exist? gravGty is what binds the particles together. $\endgroup$ – IDontReallyKnow Jul 27 '16 at 0:35
  • 1
    $\begingroup$ I've removed some nonconstructive comments. $\endgroup$ – David Z Jul 27 '16 at 17:04

Not the answer you're looking for? Browse other questions tagged or ask your own question.