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Universe Has 100x More Entropy Than We Thought
eldavojohn writes "Previous estimates are now thought to skimp on the entropy of the observable universe. The researchers contend that super-massive black holes are the largest contributor of entropy. Since they contribute two orders of magnitude more than previously thought, the total of all the observable universe is correspondingly higher. The paper highlights (in gruesome detail) new issues that arise with these new calculations — like estimating us a little bit closer to heat death (moving entropy totals from 10^102 to 10^104 out of a maximum of 10^122)."
I can finally move forward with the plans for my Entropy Cannon.
Here's a link for anyone curious about the Heat Death of the Universe concept
I propose a Fourth Law of Thermodynamics: There's more entropy than you think there is.
Universe Has 100x More Entropy Than We Thought
Scientists must have discovered my daughters room.
Because of Neutron decay we've only 10^49 years anyway.
Everything that comes into a black hole comes back out eventually via Hawking Radiation. It goes in as a star or a chicken or a pistachio and comes out as random energy, which is a pretty clear increase in entropy.
"I zero-index my hamsters" - Willtor (147206)
With the "news" (circa 1998) that the rate of expansion of the universe is increasing, it seems to me that worries about the heat death of the universe should be put on hold. There's something (currently labeled "dark energy") about cosmology that we simply lack sufficient understanding of.
The universe is still expanding in all directions at the speed of light, then the entropy per unit volume will still stay low enough to be habitable, right? Or is the problem that the rate of increase in volume will not keep pace, since it takes longer and longer for the universe to double in volume at a constant rate of expansion?
The researchers contend that super-massive black holes are the largest contributor of entropy.
I have also heard that "glaciers melting in the dead of night" contribute to entropy quite a bit.
Vivin Suresh Paliath
http://vivin.net
I like
"Order" and "disorder" are human perceptions, not states of matter and energy. Sometimes we perceive more order when there are clear differences in energy states, sometimes we perceive less
To you, which is more ordered: a bowl of cherries next to a glass of water, or a completely smooth blend of all of them? The latter is more entropic. In the case of the room, replace the garbage bin with an incinerator, and the "empty" room (plus the stuff that used to be in it) is now in a more entropic state. The fact that you personally find it tidier isn't relevant. Assuming that you might have actually needed some of the stuff that we just burned, too, you might find it a rather poor solution to the problem of a messy room.
The flaw is that entropy is not exactly synonymous with disorder. Sometimes it is, if a disordered state has a lower energy potential than a higher ordered states. But in many cases, such as falling to the bottom of a gravity well, the "ordered" - actually just more compact - state is the lower energy state. Entropy is just the degree to which a system has moved from a higher energy potential to a lower energy potential. If we had more potential energy after falling into a gravity well than before it, then we'd need rockets to blast ourselves from space back to Earth, rather than the other way around.
If you don't know where you are going, you will wind up somewhere else.
Wow, Vogons posting on slashdot!
Free Martian Whores!
being haughty to AC is like shouting at a tree because a squirrel annoyed you.
I don't see anything wrong with the intent of the question. Maybe he read it and found it too complex. Maybe he didn't understand it at all. Maybe he didn't read it and thought Slashdotters could give the best answer - in any case, no one's forcing you to answer his question.
I'm afraid the BAC analogy really isn't appilcable. You're describing an impurity which builds up to a critical level to "kill" the host, and pointing out that if you could sequester the impurity the sequestered quantity wouldn't matter. Entropy is not an impurity that is slowly building up to eventually cause the universe to break; it's nothing like that at all.
I find it conceptually confusing to think about entropy as a finite/positive quantity. The way it's defined mathematically, of course, it is ... but at a physical level there's just something backwards about it.
Entropy describes the degree to which energy in a system isn't usable. If you consider as a closed system a bit of ice in a glass of hot water: the heat in the water is "useful" in this system. It will melt the ice, and then equalize the temperature of the water from the melted ice to that of the rest of the water. (That may not seem "useful"; I suppose the point is other processes could capture and use the energy for other ends.)
But, as the ice melts and the water temperature equalizes (or as any other process fuels itself by accelerating this process), you don't run out of energy (which is constant) - but you do run out of "usability" of energy. When your system contains only water at a fixed temperature, there is no way to make heat flow, and all of teh energy in the system is useless. (Again, this assumesa closed system.)
So the point with black holes is, they aren't sequestering entropy to keep it from harming the universe in some way (like your BAC example); if anything they sequester energy and keep it from interacting with the rest of the universe, rendering it useless. (Not sure how Hawking radiation fits in that analysis, though.)