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Argonne researchers posit way to locally circumvent Second Law of Thermodynamics

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Re: Argonne researchers posit way to locally circumvent Second Law of Thermodynamics

#71

Post by tedsanders »

beagle3 wrote: post #40
ThePhysicist wrote: post #34

The second law of thermodynamics isn't really a fundamental physical law, but rather a promise based on statistics that says "disorder will increase or stay constant in a closed physical system". That said, it's entirely possible for entropy to spontaneously decrease in a closed system, the probability of this happening is just astronomically small for typical macroscopic systems. Example: If you have a system consis…

The second law of thermodynamics is as fundamental as the uncertainty principle: The former is a result from markov chains and information theory, the latter is a result from fourier analysis of conjugate variables. What would you consider a "fundamental physical law"?

Would you mind sharing a link to a proof of the second law using Markov chains and information theory? I'd like to learn more about this approach.

I'm surprised that Markov chains would be involved when the laws of physics are deterministic.

The Poincare recurrence theorem has always suggested to me that the second law is not as fundamental as other laws. For a finite system with finite phase space, the state of a system will traverse closed loops, repeating forever with no steady increase or decrease in entropy. (Edit: to be clear, I'm not claiming that what I just described is the Poincare recurrence theorem or that it applies to our universe. But it is worth considering systems where the second law doesn't apply and trying to figure out how and if they differ critically from reality.)

https://en.wikipedia.org/wiki/Poincar%C3%A9_recurrence_theor...

Not that my background is worth anything, but just so you know where I'm coming from, I have a PhD in physics, spent years thinking about the entropy of computation, and wrote parts of the Wikipedia entry on Maxwell's demon. I think much of the disagreement over entropy and the second law comes from how we frame the problem.

Re: Argonne researchers posit way to locally circumvent Second Law of Thermodynamics

#72

Post by ThePhysicist »

clairity wrote: post #62
ThePhysicist wrote: post #34

The second law of thermodynamics isn't really a fundamental physical law, but rather a promise based on statistics that says "disorder will increase or stay constant in a closed physical system". That said, it's entirely possible for entropy to spontaneously decrease in a closed system, the probability of this happening is just astronomically small for typical macroscopic systems. Example: If you have a system consis…

aren't people (and all living organisms) the quintessential example of a local decrease in entropy that results in greater overall entropy? we are highly ordered groupings of matter but we're really great at churning about the matter and energy around us and we eventually decompose too.

Yes absolutely! Life is actually a way to increase entropy as it harnesses chemical energy in systems that otherwise wouldn't be able to reach a lower energy state by themselves.

Re: Argonne researchers posit way to locally circumvent Second Law of Thermodynamics

#73

Post by jrapdx3 »

clairity wrote: post #62
ThePhysicist wrote: post #34

The second law of thermodynamics isn't really a fundamental physical law, but rather a promise based on statistics that says "disorder will increase or stay constant in a closed physical system". That said, it's entirely possible for entropy to spontaneously decrease in a closed system, the probability of this happening is just astronomically small for typical macroscopic systems. Example: If you have a system consis…

aren't people (and all living organisms) the quintessential example of a local decrease in entropy that results in greater overall entropy? we are highly ordered groupings of matter but we're really great at churning about the matter and energy around us and we eventually decompose too.

A living organism is of course a noble endeavor standing against the tide of entropy. But it can do so only with significant influx of energy extracted from its external environment. The cost of constructing such an elaborate order of matter is paid by disorder elsewhere.

As we know, the living stance can be maintained for only a relatively short time, after which it rapidly decomposes to background entropy.

Interesting to speculate, as living beings we are chock full of "micro-environments", there could be exceptions to the laws of nature as we've understood them that could account for certain mysteries of biological nature.

Re: Argonne researchers posit way to locally circumvent Second Law of Thermodynamics

#74

Post by pavel_lishin »

TeMPOraL wrote: post #27
eli_gottlieb wrote: post #21

Earlier quoted context omitted.

Several Doom games, and also Half-Life. Ripping a hole into Hell for travel purposes has been done in Doom, the movie Event Horizon, and the tabletop gaming franchise Warhammer 40K. Which goes to show what a terrible idea this all is ;-).

Also done in an excellent though unfinished series of books, The Salvation War[0]. Albeit travel was only a side effect of the real goal there. [0] - http://www.tboverse.us/HPCAFORUM/phpBB3/viewforum.php?f=29 - full text of Armageddon and Pantheocide available there; the author decided to abandon the series because someone stole his work to destroy his ability to publish it.

> the author decided to abandon the series because someone stole his work to destroy his ability to publish it.

What do you mean? It seems like the author was publishing it for free online already; how would one steal that work and prevent him from publishing?

Re: Argonne researchers posit way to locally circumvent Second Law of Thermodynamics

#75

Post by crpatino »

You lost me at "locally". Of course if you take a closed system A and make it a subsistem of some bigger closed system B you are going to be able to diminish entropy at A by increasing entropy even further at (B + !A).

My grandmother's freezer was doing this 50 years ago, and I am pretty sure the engineers who designed it did not think their work was fundamental research in any way or form.

Re: Argonne researchers posit way to locally circumvent Second Law of Thermodynamics

#76

Post by beagle3 »

tedsanders wrote: post #71
beagle3 wrote: post #40

Earlier quoted context omitted.

The second law of thermodynamics is as fundamental as the uncertainty principle: The former is a result from markov chains and information theory, the latter is a result from fourier analysis of conjugate variables. What would you consider a "fundamental physical law"?

Would you mind sharing a link to a proof of the second law using Markov chains and information theory? I'd like to learn more about this approach. I'm surprised that Markov chains would be involved when the laws of physics are deterministic. The Poincare recurrence theorem has always suggested to me that the second law is not as fundamental as other laws. For a finite system with finite phase space, the state of a sy…

I am on mobile now, and can't provide a simple link, but it is given in Cover&Thomas "Elements of Information Theory", in the episode that discusses entropy of markov processes. I can find pages in google books but they won't zoom big enough to read...

IIRC, the proof requires the markov chain be irreducible, and extends to the general case by summing over the irreducible parts; and that entropy will stay the same or increase while converging to the stationary distribution over states.

(Although it has now been 20 years since I dealt with these things so I might be misremembering. Time to retread Cover&Thomas I guess...)

Re: Argonne researchers posit way to locally circumvent Second Law of Thermodynamics

#77

Post by klank »

beagle3 wrote: post #40
ThePhysicist wrote: post #34

The second law of thermodynamics isn't really a fundamental physical law, but rather a promise based on statistics that says "disorder will increase or stay constant in a closed physical system". That said, it's entirely possible for entropy to spontaneously decrease in a closed system, the probability of this happening is just astronomically small for typical macroscopic systems. Example: If you have a system consis…

The second law of thermodynamics is as fundamental as the uncertainty principle: The former is a result from markov chains and information theory, the latter is a result from fourier analysis of conjugate variables. What would you consider a "fundamental physical law"?

I believe a distinction could be made around the second law of thermodynamics being emergent rather than, well, fundamental.

Put another way: the second law of thermodynamics is not required to fully describe a universe that acts like ours appears to. It will "take care of itself" based on more fundamental descriptions of matter and its interactions.

I'm also comfortable with what appears to be fundamental today no longer being fundamental tomorrow.

Re: Argonne researchers posit way to locally circumvent Second Law of Thermodynamics

#78

Post by raattgift »

maxerickson wrote: post #24
btilly wrote: post #12

Earlier quoted context omitted.

Ironically someone downvoted you for this comment. I guess that they didn't understand how exactly true your statement is. In essence the entire biosphere is a giant heat engine, mainly fed off of the flow of energy from the Sun to Earth to outer space, and in some extreme environments fed by the radiation of heat out from the core of the Earth. Shut off those flows of energy, and the second law would shortly catch u…

Shut off the flow of energy and the cold would catch up to us a long time before the second law of thermodynamics. (our frozen, desiccated corpses would probably retain their organization longer under such conditions)

But as they're frozen, the ratio of possible microstates to each colder, dryer macrostate increases tremendously. S = k log W. Entropy sets in well before algor mortis.

Re: Argonne researchers posit way to locally circumvent Second Law of Thermodynamics

#80

Post by Balgair »

greydius wrote: post #61
beagle3 wrote: post #40

Earlier quoted context omitted.

The second law of thermodynamics is as fundamental as the uncertainty principle: The former is a result from markov chains and information theory, the latter is a result from fourier analysis of conjugate variables. What would you consider a "fundamental physical law"?

Nature is under no obligation to comply with mathematical analysis.

Especially as the subject is quantum physics and thermodynamics, this is a very interesting viewpoint. Though I agree with you in principle, many centuries of inquiry about our universe by some of the most intelligent humans to date seems to say that mathematical formulations and ideas are the best (if not only, as with QM) way to think about our universe. No other way has really been as incredibly useful in terms of prediction as a mathematical one. I think you do have a point, but I will continue to take the so-called Copenhagen Interpretation of QM: Shut Up and Calculate.
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