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Thread: Gravity as an entropic force

  1. #1 Gravity as an entropic force 
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    I came across this paper today which describes gravity as an entropic force. Gravity is described as a entropic force arising from change in the amount of information associated with the change in positions of bodies of matter.
    http://arxiv.org/pdf/1001.0785v1.pdf
    From what I can gather it received mixed reviews. Some considered it profound and others trivial and already well understood. I would be interested in your opinions.
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  2. #2  
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    I get really iffy on papers of gravity and would trust textbooks more than unpublished articles.

    Should we attribute gravitation to the curvature of spacetime due to the
    presence of masses or to a force between masses? Or should we attribute it to
    the actions of a type of fundamental particle called a graviton, as conjectured in
    some modern physics theories? Although our theories about gravitation have
    been enormously successful in describing everything from falling apples to planetary
    and stellar motions, we still do not fully understand it on either the cosmological
    scale or the quantum physics scale.


    Didn't read the article, but describing gravity as an entropic force already loses. A quantum theory of gravity is what is desired more, I think.
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  3. #3  
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    Oh, I should have said that it was published. I think this was the preprint. I'm pretty sure as it stands it is incompatible with QM. As this paper explains.
    [1108.4161] Once more: gravity is not an entropic force
    I think perhaps they are missing the point somewhat though. The statistics would need to be modified to apply to quantum particles in my view.
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  4. #4  
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    OK, can someone tell me what an entropic force is? In physics, an entropic force acting in a system is a phenomenological force resulting from the entire system's statistical tendency to increase its entropy, rather than from a particular underlying microscopic force.[1]

    Entropic force - Wikipedia, the free encyclopedia

    Gravity being a force that increases entropy is like totally counter intuitive. Briefly reading the abstracts of those arxiv articles seems to me they contradict each other.

    :EDIT:

    Also, in my quote "...we still do not fully understand it on either the cosmological scale or the quantum physics scale." Throws me off a bit cause I thought it was only a quantum theory of gravity that was needed, but a cosmological one?

    I'd like to research on my own but like... I remember my dad reproaching me with words like "Your eyes are bigger than your stomach."
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  5. #5  
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    You really should read the first few pages of the first paper. It describes it quite well and is very readable.
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    In reply to Jilan, re: your #1 post.

    Do you remember the posit I wrote over at "phys?" The one where I proposed that gravity exists as a "potential" that is made manifest by the existence of matter?

    .....

    Your link reference reminds me of my own views with regard to "quantum-dimension gravity"...however cagily they are phrasing it!


    (Thanks!)
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    Quote Originally Posted by Jilan View Post
    You really should read the first few pages of the first paper. It describes it quite well and is very readable.
    eh... I was trying to say that I don't want to put too much on my plate. My university uses Maple more over Mathematica. Since I've played with Mathematica exclusively, I'm kinda' at a disadvantage -as it's probably the best God damn chance I have to do anything with my pathetic life! I Need to put effort into learning how to manipulate the program better. As in knowing that you screwed up in your math beforehand. Hence, I've got some instructional books on it, and was hoping people had some thoughts and volunteer information on gravity. The title of this thread is like crank -entropy can increase with time but a black hole didn't get the memo.
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    Quote Originally Posted by Gerry Nightingale View Post
    In reply to Jilan, re: your #1 post.

    Do you remember the posit I wrote over at "phys?" The one where I proposed that gravity exists as a "potential" that is made manifest by the existence of matter?

    .....

    Your link reference reminds me of my own views with regard to "quantum-dimension gravity"...however cagily they are phrasing it!


    (Thanks!)
    Yes Gerry, I remember.
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    Quote Originally Posted by Beer w/Straw View Post
    eh... I was trying to say that I don't want to put too much on my plate. My university uses Maple more over Mathematica. Since I've played with Mathematica exclusively, I'm kinda' at a disadvantage -as it's probably the best God damn chance I have to do anything with my pathetic life! I Need to put effort into learning how to manipulate the program better. As in knowing that you screwed up in your math beforehand. Hence, I've got some instructional books on it, and was hoping people had some thoughts and volunteer information on gravity. The title of this thread is like crank -entropy can increase with time but a black hole didn't get the memo.
    I think your entropy would increase if you fell into a black hole, LOL! Thinking a bit more about forces over my breakfast, I wonder if all forces could be described this way, as entropy tends to increase.....
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    Well, what do you know - Look what I just found....
    http://iopscience.iop.org/1742-6596/...3_1_012024.pdf
    Regarding an entropic understanding of the Coloumb force. In their conclusion they suggest that the entropic force idea might be a new paradigm applying to all forces. Interesting.

    In a thread a while back I recall KJW or btr mentioning that it all comes down to information in the end. I am starting to see the wisdom of that.
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    Quote Originally Posted by Jilan View Post
    ...I would be interested in your opinions.
    I think it's pseudoscience cargo-cult junk. As is the idea that it all comes down to information in the end. Here's a quote from the Wikipedia article:

    "This model combines the thermodynamic approach to gravity with Gerardus 't Hooft's holographic principle. It implies that gravity is not a fundamental interaction, but an emergent phenomenon which arises from the statistical behavior of microscopic degrees of freedom encoded on a holographic screen..."

    Gravity isn't thermodynamic, it's geometrical. And what holographic principle? It's "a property of string theories and a supposed property of quantum gravity that states that the description of a volume of space can be thought of as encoded on a boundary to the region". Space is space. It has a volume. So what holographic screen? There isn't one. Don't fall for this woo Jilan. Sure, have an enquiring mind, but don't get suckered into believing in Emperor's New Clothes non-explanations that totally ignore general relativity, which is just about the best-test theory we've got. Oh, and note that entropic gravity "can not be falsified with existing experimental methods". Very handy that.
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    Anyway, I tend to think of the entire universe as a system. Not the entropy of an isolated one.
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    In reply to Beer w/ Straw, re: your ? post.

    "blackhole" did not get memo"...very good!

    I think the messenger could NOT find any "blackhole" to deliver the memo to...you must have an imaginary messenger to deliver memos' to imaginary structures!

    (all that is needed is more calculus to accomplish the delivery)


    (Thanks for reading!)
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    Very good, thanks for your input. We have two votes for crank Physics so far. Anyone else have an opinion?
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    Is there something wrong with equating entropy as the expansion of the universe?
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  16. #16  
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    If you drop a bit of ink in a glass of water it spreads out. I don't think that has much to do with the size of the universe. It just the statistics of available configurations that makes it the case.
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    I don't know if you are deliberately trying to put me down or not. I already made a distinction: "Anyway, I tend to think of the entire universe as a system. Not the entropy of an isolated one."

    Are you of the opinion black holes don't exist? Are you of the opinion the Big Bang theory is total crap?
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  18. #18  
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    No, no and no. I just don't see how it's relevant to the thread.
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    Then I would be at a loss as to your motives.
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  20. #20  
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    Just trying to ascertain whether the idea has merit or not. Nothing sinister.
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    In reply to BeerW/ Straw, re: your #17 post.

    Sorry if you think I'm "toying" with you...I'm not. Please accept my apology if you got that impression!

    .....

    Do I think "BB" theory is "grasping at straws?" YES. (can I be wrong? also yes) Is "BH" theory also suspect, to me? YES(sq.) (can I be wrong again? Sure!)

    My thinking-cap just won't allow some things thru...and I have yet to be able to take it off! I wish I knew WTH is wrong with me.


    (Thanks for reading!)
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    In further reply to Jilan, re: your #1 post.

    Okaaaay...I read the "whole thing!" (promise)

    And my assessment is "I don't know WTH they are trying to convey!" Colloidal pressure gradients? Temperatures? It seems they are trying to establish gravity as an actual, physical

    "thing!" (at least it seems that way to me) Honestly, I'm lost here! There are so many odd tangents in play I just plain don't know what they trying to posit!

    (I think maybe they are shooting for a "sort of" corpuscular graviton?)


    .....

    Still, it was an interesting "link!" and I always like new stuff.


    (Thanks for reading!)
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    Well some of my favorites are WMAP and HST. So that must mean that I'm a stupid f"ing moron.
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  24. #24  
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    Beer w/Straw. Why a would you say a thing like that? Gravity probe experiments are really interesting.
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    WMAP for the cosmic background radiation , and HST for black holes.




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    Yes, they are great, but why does that make you a moron? I don't get it.
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    I don't have a thinking cap like Gerry. So, I must be.
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  28. #28  
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    You are misreading what he said. He is frustrated that his thinking cap won't let things through and he wishes he could take it off. I would take that to mean that life's schemas are getting in the way of a good understanding. We all have that issue in common.
    Gerry Nightingale likes this.
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  29. #29  
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    No.

    Let him tell me I'm moron or not.
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    In reply to Beer w/Straw, re: your #29 post.

    No, I have serious doubt that you would fall in the "moron" category. I was speaking of a metaphorical "block" in my head with regard to how I see things. (the pictures are pretty, by the

    way) I see no possibility of "blackhole" formations, pictures or no. The picture-maps have been "enhanced" to "show what we want to see" and they then "mean what we want them

    to mean". My "thinking-cap" will not allow me to "accept and believe" the fantastic propositions that are attributed to such an entity, no matter who says it is correct!

    (I would not last an hour in a real "physics class" environment, at least not with regard to theory...I think my mind has calcinated to the point of no return due to age)

    .....

    I once wrote Jilan to ignore everything I say regarding physics, as she is a student and does not need to be contaminated with my personal demons of discordant thoughts. I will

    tell you the same thing, if you are a student...be leery of old men with old values like me.

    I wonder why I even bother to write anything, as no one "likes" it. My interpretations are so shocking I've been bounced out of 2!! forums just for daring to write them, even on

    "alternate-theory" forum. ( some things are just "too much" even in a "trash" post!)

    .....

    There are plenty of morons to spare, especially the "really smart" kind that write smarmy judgments of smug contempt to others so they can feel secure in their "knowledge of

    how to look s**t up on Wiki". It has been my experience that people who REALLY are smart don't feel any need to disparage others. Instead, they try to help others.

    I wish I could say "I am one of those people" but I place myself in the "useless ass" category<(I have many personal reasons for this, that cause me a great sense of regret and

    self-loathing...I really dislike being me)

    .....

    NO, I'm not assigning you to the "moron" class...I am the one who is an "outsider" because I KNOW modern theory very well, and I reject most if not all of it!

    (whatever made you think I was trying to "punk" you?)


    (Thanks for reading!)
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    Your post is ambiguous and I don't understand you.
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    In reply to Beer w/Straw, re: your #31 post.

    Okay. (I couldn't of anything shorter to say) Also, your post is ambiguous and I don't understand you.
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  33. #33  
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    Quote Originally Posted by Jilan View Post
    I came across this paper today which describes gravity as an entropic force. Gravity is described as a entropic force arising from change in the amount of information associated with the change in positions of bodies of matter.
    http://arxiv.org/pdf/1001.0785v1.pdf
    From what I can gather it received mixed reviews. Some considered it profound and others trivial and already well understood. I would be interested in your opinions.
    The reference is in this page - [1001.0785] On the Origin of Gravity and the Laws of Newton
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  34. #34  
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    So thinking a bit more about this entropy idea I was wondering how it would relate to statistical mechanics and whether there would be a quantum statistical approach to gravity. I found this paper which is pretty interesting too. Gravity as a quantum diffusion process. Nice!
    [gr-qc/9906079] Gravitation as a Quantum Diffusion
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    Quote Originally Posted by Jilan View Post
    So thinking a bit more about this entropy idea I was wondering how it would relate to statistical mechanics and whether there would be a quantum statistical approach to gravity. I found this paper which is pretty interesting too. Gravity as a quantum diffusion process. Nice!
    [gr-qc/9906079] Gravitation as a Quantum Diffusion
    You might, er, enjoy Lubos Motl's typically immoderate take on the general idea: The Reference Frame: Erik Verlinde: comments about the entropic force of gravity and then The Reference Frame: Why gravity can't be entropic
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  36. #36  
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    Thanks tk421' the links look interesting. Will read them properly in the morning.
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