Talk:Heat death of the universe
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[edit] THE NAME
I'm not so sure about despite its name. Heat death to me has always meant the death (nonexistance) of heat, rather than death through overheating. But maybe this is because I don't remember being confused when i first heard the term? Morwen 20:46, 10 Nov 2003 (UTC)
Hmm, I think alot of people will disagree with the idea thatan a universe that contiunes to expand will approach heat death asymptotically.
The first line of disagreement I can see is that although the 19th century scientist who came up with the idea of the heat death of the universe meant it to refer to the maximal entropy state of the universe, he was talking about a steady state model. However heat death conventionally means total thermal equilibrium (which is obviously the same as a maximal entropy state in what we'd normally think of a s a closed system) and I see no reason why an expandingf universe cannot be in thermal equilibrium before it reaches it's maximal entropy state. I'm pretty certain that in general the 'heat death of the universe' is used to describe a state that will occur after a finite period of time (i.e. the usuage I've detailed above) rather than that detailed in the article.
Secondly even if we do take heat death as equivalent to maximal entropy, does it approach really maximal entropy asymptotically? I can see why it would approach in a declerating infinitely expanding model, but I don't see why it should in one with linear or accelerating expansion. I can't say I'm 100% sure about this but in the latter two models what stops them from having arbitarily high entropies?
I think these two points do need to be clarified in the finished article.
[edit] Heat-death vs Big Freeze
As far as I can understand (and as suggested here), heat death means a flat universe dying from max entropy, and the Big Freeze is an open (constantly expanding) universe dying from expansion causing heat to be spread out - the effects are the same, but the causes different. I've updated the article a little accordingly and linked to that page, but it would be useful if someone could check that this is correct and if so explain it a bit more clearly than I've done :) --Jomel 16:17, 13 Aug 2004 (UTC)
- There defintely needs to be more clarification here. As far as I, an amateur, can perceive, the only difference is that "heat death" involves an exhaustion of all entropy whereas "big freeze" involves matter being so spread out that any residual energy is nearly useless. BOTH of these articles need a "compare & contrast" section or else I'd say that an overzealous editor may ask for them to be merged. (Which I don't feel that they should be.) Again, without it being spelled out, it's somewhat difficult to differentiate the two items. JD79 17:47, 1 June 2006 (UTC)
[edit] Helmholtz or Clausius
Does anyone please remember who originated the concept?
Acc to: http://webplaza.pt.lu/fklaess/html/HISTORIA.HTML
it was helmholtz in 1854
interestingly, Clausius is listed LATER with the second law in 1865 ..
- Admittedly, there are a few references on the web to this (only a few!) but can anyone actuall give a citation of where Helmholtz actually said this? Cutler 11:41, July 13, 2005 (UTC)
[edit] Third law of Thermodynamics
Doesn't the third law of thermodynamics play a role here, too? As in, assuming an expanding universe, the temperature will decrease to approximately zero - hence the entropy will go to zero, which I guess actually avoids the whole Heat Death at the end, ultimately going towards the Big Freeze. Or is there a way in which the temperature stays at a non-zero value? (I guess this would be possible with a critically flat universe.) Mike Peel 21:56, 15 March 2006 (UTC)
- It is my understanding that the temperature will not reach zero because heat is the "basest" form of energy and since energy can neither be created nor destroyed (more or less) then there will always be heat. There will just be a lack of any type of mechanism to change heat into anything else, and everything will be the same temperature. JD79 17:50, 1 June 2006 (UTC)
[edit] Fate of the Black Holes is wrong
Black holes will only boil away if their temperature is greater than the temperature of the background radiation. Otherwise they will continue to absorb more energy from the background radiation than they give up through Hawking radiation. At the moment (temp = 2.73 K), the tipping point is for a black hole to have approximately the mass of the planet Mercury.
The scenario in the article at the moment appears to be based on the Big Freeze scenario, with the CMB temperature continuing to fall as the universe continues to expand.
But what happens with the Heat Death scenario? Any little black holes presumably boil away. But bigger black holes continue to grow, taking energy from the CMB, which makes it cooler. This may make more of the black holes too small to survive. Eventually, presumably, only the biggest coldest black hole of the lot survives, in thermal equilibrium with the CMB.
At least that's how it would seem to me to have to go. Jheald 13:10, 6 July 2006 (UTC).
- I copied the detailed walkthrough of the scenario from an old verion of Timeline of the Universe, which was later merged into Timeline of the Big Bang, to the exclusion of this material. The relevant version, which was the last major one before the merge, is at http://en.wikipedia.org/w/index.php?title=Timeline_of_the_Universe&oldid=28769719
- I don't actually have a lot of familiarity with the topic myself. At least, not enough to spot and correct technical errors. If you've got some relevant sources, by all means, go ahead and make the edit. The information here is well over a year old now, and even if it was correct at the time it wouldn't be surprising if this is now outdated. Arturus 03:45, 7 July 2006 (UTC)
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- I'd prefer to leave any final change to someone who's more of an expert. I just think what's in the article at the moment is not correct, if we're not talking about the Big Freeze. Jheald 17:51, 7 July 2006 (UTC).
[edit] Ultimate fate
"even smallest perturbations make the biggest difference in this era"
I suspect that this is poorly worded and should say something more like ""even small perturbations make a big difference in this era".
[edit] Timeline for heat death
I'm no Wikipedia formatting expert, so I'll just pose the question: is there a way to preserve the formatting in the "Timeline for heat death" in the table of contents on the main page? It looks like the black hole age is just 1040 years away, rather than 10^40 years away. Jyoshimi 18:42, 17 October 2006 (UTC)
- You could just right 10E40 instead of 1040. I assume most people would understand. (68.98.52.155 01:17, 1 November 2006 (UTC))
