Over in the thread on The event horizon of a white hole it was said that one reason arguing against a white hole’s existence is that it violates the Second Law of Thermodynamics (loosely…entropy always increases).
While doing a little spinning around the internet for info on White Holes I saw it suggested that the Big Bang might be considered a White Hole in its own right. In some cases it certainly fits the parameters of a white hole (e.g. nothing can go into it, spewing forth matter, etc.).
Regardless if the Big Bang = White Hole is supportable or not it got me to wondering how the Big Bang itself avoided the Second Law of Thermodynamics.
To my mind it would seem as if post Big Bang (say T plus 0.00001 seconds) the universe was a highly disordered place. Particles whizzing to and fro…not locked into any form or matter and so on. Eventually the particles settled down a bit and got more ordered, eventually forming matter and then stars and planets and mosquitos.
Am I missing something here? Was the very very early universe considered a more ordered place than it is now (thus avoiding violations of the second law)? Or was the early universe somehow immune from such legalities? If it was immune is there a moment scientists defined as when the Second Law kicked in?
[sub]NOTE: I seem to remember this being discussed here before but the search I ran turned up either far too many threads to be worth checking or my search was too narrow and got nothing. I apologize if this is a repeat…feel free to point me to existing threads if they exist and you find them.[/sub]
The difference, I think, is the volume of the early universe. It was much smaller than the modern universe, allowing it to have a higher temperature, but still be more organized. Imagine a box of marbles. If you have a box so small that every marble must be pretty close to cubic packing in order to fit in the box, then it doesn’t matter how fast you shake the box (i.e., how high the “temperature” of the marble particles is), it is still highly organized due to the constraints on physical size. If you throw the contents of the box across the floor, the marbles will eventually slow (“cool”), but will be more disorganized due to the larger space they are able to occupy. The universe is similar: the apparent low entropy of collections of mass like stars and planets is more than made up for by the vast empty distances filled with dust, stray atoms, and photons. The Second Law of Thermodynamics has been valid since immediately after the Big Bang. At least, we think so.
The second law of thermodynamics is typically minsunderstood as you stated it. Closed systems tend toward entropy which is not even the same as “entropy always increases.”
As for order of the early universe how many ways can you arrange a singularity? We have option A: all space, time, matter and energy are squeezed into one point. Option B: …uh. Maybe trying to compare the order of the singularity with the later universe is like trying to devide by zero.
Basically the second law of thermodynamics kicked in when the universe started to expand, the inbalance between chaos and order is from the fact that there are still regions left from the big-bang with a high density, while other regions have lower densities.
I got my info both from the other thread and while looking about the web. Here is one such mention:
If I mistated or mislead I apologize.
Understood and I even considered that. Still, I figured that it seemed there was more disorder than order for at least a few seconds post Big Bang such that the Second Law might be violated (or seem to be). While I may be mistating the use of the Second Law in the micro sense I think the macro sense of the entire universe possibly becoming more ordered would certainly fly in the face of the Second Law.
I was wondering if something like Inflation Theory explained away this apparent violation. If the Universe could expand quicker than the speed of light for awhile what’s the big deal with mucking about with thermodynamics?
The trouble with this explanation is by this reasoning the big crunch, should it ever occur (highly unlikely), would also have a very low entropy. But we know this cannot be true.
At the present time I don’t believe there’s an answer to this question. The calculated odds of the universe starting out with very low entropy is something like one part in 10^10[sup]123[/sup]
Do we know that that cannot be true? I’m no expert, but if I remember correctly, Stephen Hawking speculated that when the universe reached maximum size and began collapsing, the Second Law of Thermodynamics would reverse itself. But perhaps he’s abandoned that theory by now. Not that it matters of course, since the universe is almost surely not only open, but accelerating.
To say that the Big Bang violates the Second Law, you would have to say that the entropy was higher before the Big Bang than after it. There’s a problem with this, though: There was no “before”. After the Bang, entropy has been continually increasing (even, I’m pretty sure, before a Planck time had passed). Yes, shortly after t=0, the Universe was a very entropic place. Right now, it’s even more entropic. And just before the Crunch, should it come, it’ll be even more so.
In a previous thread, I argued essentially that: The maximum entropy of a closed system with constant energy (like the universe, presumably), is proportional to its volume. If the universe is collapsing, its volume is decreasing, so its maximum possible entropy is decreasing. At some point, the maximum possible entropy falls below the universe’s entropy, so the universe’s entropy must start decreasing. This would happen somewhere between the time when the universe reached its maximum size, and the final big crunch.
I had a link at the time that stated this had been shown not to be true, but the comment was just an aside, with no supporting argument. Anybody have any thoughts on where my argument fails?
The Second Law is not really about order (or the lack thereof) but usable energy. It is just that the decrease in usuable energy (in a closed system) conincide with the decrease in order rather often. However, you should not think that the Second Law is about the increase in chaos.
This seems counter-intuitive although unfortunately much of science these days seems to fly in the face of intuition so what can a guy do?
Still, I find it hard to believe that the Universe at (say) T=1 second, with particles whizzing about at exceedingly high temperatures, was a more ordered place than it is today (or at least when the plasma soup of the early universe settled down into matter).
Actually, I thought increasing temperature increased entropy. How does a cooling universe increase in entropy over the earlier, much hotter universe?
Another thing about the Second Law is it is not absolute, it is a statistical law about a closed system. Therefore, I reckon white holes can exist as long as there is no overall increase in the whole universe. If you cannot have an increase at certain places at the expense of overall decrease, life is impossible.
Bryanmcc, ZenBeam The eminent physicist John Baez discusses this topic in the below article. I’ll include a little of here, but I suggest you read the whole thing. however, Roger Penrose in his book “The Emperor’s New Mind” flatly states that the big crunch would have very high entropy. And, of course, so does Chronos.
Beeblebrox, yes, of course I meant hexagonal packing. Sorry for the brain fart. The fingers no typing what the brain be thinking.
Whack-a-Mole, entropy increases as temperature increases for a system of constant volume. If the volume is increasing at a constant temperature, entropy increases due to more space for the contents to spread out in. If volume is increasing and temperature is decreasing (which will usually be the case) then it depends on the rate of change of each whether the entropy increases or decreases.
Ring, very interesting. Thanks for the info! Perhaps another reason why the universe must be open (however aesthetically unappealing that may be).