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Space Science

Universe Has 100x More Entropy Than We Thought 304

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)."
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Universe Has 100x More Entropy Than We Thought

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  • we're doomed anyway (Score:5, Interesting)

    by prgrmr ( 568806 ) on Tuesday October 06, 2009 @01:51PM (#29659933) Journal
    Because of Neutron decay [] we've only 10^49 years anyway.
  • Re:Heat Death (Score:5, Interesting)

    by MozeeToby ( 1163751 ) on Tuesday October 06, 2009 @01:55PM (#29660023)

    It's interesting to note that even with the new estimate being 100X greater than the old, the new data is still only a billionth of a billionth of the maximum value. What, if anything, does that mean for the past and future of the universe? Reminds me of the Stephen Baxter book Manifold: Time, where the age of stars and galaxies is thought of in the same way we think of the instant right after the big bang.

  • by rwa2 ( 4391 ) * on Tuesday October 06, 2009 @02:06PM (#29660177) Homepage Journal
    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?
  • by Anonymous Coward on Tuesday October 06, 2009 @02:16PM (#29660405)

    But that dirt in the back of the car has weight, just as the black hole.

    in the car analogy it gets less total distance because of the extra weight, Same with the universe, If more matter is locked up in black holes, Obviously there is less matter outside of the black holes. Therefore sooner heat death.

  • by amliebsch ( 724858 ) on Tuesday October 06, 2009 @02:17PM (#29660421) Journal

    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.

  • by mea37 ( 1201159 ) on Tuesday October 06, 2009 @03:01PM (#29661105)

    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.)

  • by catmistake ( 814204 ) on Tuesday October 06, 2009 @03:30PM (#29661501) Journal
    Not RTFA.
    TFS fails to use them, so I must ask,
    What are the units of entropy? Can they be useful at a macroscopic level... like in describing how much entropy your bedroom contains (before it simply must be cleaned)?
  • by Max_W ( 812974 ) on Tuesday October 06, 2009 @04:02PM (#29662059)

    Where the universe is expanding? Into another universe? Into emptiness? Into nothing? Is there any rational explanation? Or is it unknown yet?

  • Re:Heat Death (Score:3, Interesting)

    by gmhowell ( 26755 ) <> on Wednesday October 07, 2009 @01:36AM (#29666701) Homepage Journal

    Fully understanding this concept led me to drink heavily in college and drop chemistry as a major. Seriously.

  • Re:Heat Death (Score:3, Interesting)

    by bronney ( 638318 ) on Wednesday October 07, 2009 @03:50AM (#29667255) Homepage

    Not to be a smart ass and shit, but the "mind" you describe, sounds like a "book", or a symphony. We already have "minds" that survives. If there's no input or output, nobody can hear the tree falls. And hence whether it is objectively alive (or conscious) isn't meaningful.

    The problem I see is, when the sun explodes, when all suns explodes, your book won't be there. Not going in the multiverse thing at all here.

  • Re:Heat Death (Score:1, Interesting)

    by ShieldW0lf ( 601553 ) on Wednesday October 07, 2009 @05:40AM (#29667693) Journal

    The "Heat Death" concept, the concept that the universe is infinite, and infinitely expanding... these just don't make sense. Gravity and Entropy both imply that the universe will not infinitely expand, but will contract back to the singularity and then expand outward again. Other theoreticians have called it "The Big Crunch" []

    If you think of time as another spatial dimension, matter and energy as being two forms of the same thing and the universe as a 4 dimensional "object" with a shape and a surface, you can envision the universe as a kind of soap bubble that has a surface tension, and the topology of that object implies gravitational forces and entropy. The "singularity" or "black hole" is the lowest common denominator state of the mass/energy of the universe.

    Dark matter is also implied by such a model. I suspect dark matter to be other universes, other iterations of the singularity expanding and collapsing, similar to this one and attached to this one.

    We are limited by our conception of time... we are stuck in the view that we are 3 dimensional objects that, over time, are transforming and translating within space. But time is an illusion. You, in your previous configuration, are not annihilated and replaced by this new configuration. You continue to exist at the moment of your birth and of your death just as you exist at this moment. This life of yours does not end in the sense that it is gone, but only in the sense that you are "over there". Your birth and death are a part of your surface, just like your skin is.

    "God" aka "The Universe" really does not play dice. Causality exists, therefore, the future and the past abide. If the future was not connected to the past, then causality would not exist, and learning of any sort would not be possible. This isn't a new idea... this is what "Faith" was always telling you to recognize... that the universe has a shape, that causality exists, and that learning is possible. Calling the shape of the universe it's "Personality" is just a matter of terminology.

    If you find this sort of thing confusing to think about, reading "Flatland" is a good way to jog the mind. Flatland and A Wrinkle in Time were the books I used to introduce these concepts to my daughter so I could explain how I look at the world to her... you can grab a copy of Flatland at Project Gutenberg. []

    Anything written by Rudy Rucker is good too. His book The Sex Sphere did more to make me interested in theoretical physics than any teacher I ever had.

Karl's version of Parkinson's Law: Work expands to exceed the time alloted it.