The second law of the thermodynamics and philosophy

[Ronemberg Junior]

The second law of thermodynamics tells us that the amount of useful energy in an isolated system tends to decrease. Does this imply that mankind will reach a point where it cannot longer use any kind of energy? If so, do we have an estimate of how long it will be necessary for to haven't useful work?

 

[Gaussian97]

Yes, this idea is called "Big Freeze" https://en.wikipedia.org/wiki/Heat_death_of_the_universe

 

[PeroK]

Summary: the second law implies in what kind of philosophical reasoning? would the universe simply "die"?

The second law of thermodynamics tells us that the amount of useful energy in an isolated system tends to decrease. Does this imply that mankind will reach a point where it cannot longer use any kind of energy? If so, do we have an estimate of how long it will be necessary for to haven't useful work?

If you are worried about that you must be planning to stick around for a very long time.

 

[zanick]

is the Earth a "closed system" since by definition a closed system is one that can exchange energy outside of its barriers.. (but not mass) is the 2nd law ONLY applicable for closed and isolated systems? AND if the Earth is closed, why is it not "open" if we do exchange mass with the universe. we take on meteors, cosmic rays, particles and we send out space craft. so technically, it should be open correct?

 

[A.T.]

so technically, it should be open correct?

Sure.

 

[zanick]

Its been awhile, but i was under the impression that the 2nd law only applies to isolated or closed systems. makes sense, since if a system is open, usable energy could always be added from out side of that system.

 

[zanick]

i meant "entropy" not the 2nd law... i suppose there is universal application of the 2nd law in open, closed or isolated systems, but entropy i was of the understanding that it only applied to closed or isolated systems. No?

 

[Chestermiller]

i meant "entropy" not the 2nd law... i suppose there is universal application of the 2nd law in open, closed or isolated systems, but entropy i was of the understanding that it only applied to closed or isolated systems. No?

No. Entropy is a physical property of each material comprising a system, and the system can be open or closed. Also, there are open system versions of both the first law of thermodynamics and the 2nd law of thermodynamics.

 

[zanick]

Yes... agreed... like a cup of coffee cooling or the sun where their entropy is going down, but going up somewhere else equal or more .

 

[Demystifier]

Much before the entropy death there will be complexity "death", or more precisely the point at which complexity will start to decrease. Consider a self-organizing system such as life in general or human civilization in particular. Such systems typically have two phases of evolution. In the first phase, both entropy and complexity grow. In the second phase, entropy still grows but complexity decreases. The first phase is the phase in which life and civilization show progress over time. In the second phase the progress is replaced with regress. We on Earth are still in the progress phase (the complexity still grows), but it might turn into a regress in a not so far future.

 

[Chestermiller]

Much before the entropy death there will be complexity "death", or more precisely the point at which complexity will start to decrease. Consider a self-organizing system such as life in general or human civilization in particular. Such systems typically have two phases of evolution. In the first phase, both entropy and complexity grow. In the second phase, entropy still grows but complexity decreases. The first phase is the phase in which life and civilization show progress over time. In the second phase the progress is replaced with regress. We on Earth are still in the progress phase (the complexity still grows), but it might turn into a regress in a not so far future.
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What has this got to do with thermodynamic entropy?

 

[BWV]

Much before the entropy death there will be complexity "death", or more precisely the point at which complexity will start to decrease. Consider a self-organizing system such as life in general or human civilization in particular. Such systems typically have two phases of evolution. In the first phase, both entropy and complexity grow. In the second phase, entropy still grows but complexity decreases. The first phase is the phase in which life and civilization show progress over time. In the second phase the progress is replaced with regress. We on Earth are still in the progress phase (the complexity still grows), but it might turn into a regress in a not so far future.

Was the Roman Empire at its peak a higher or lower entropy state for the Mediterranean region than how it existed a thousand years later or a thousand years before? Aren't you just using entropy as a metaphor rather than a scientific term with a precise meaning? Also, using the precise term, is not the collection of cells in my body is a lower entropy state than a similar number of unicellular organisms in some primordial sea?

 

[Demystifier]

What has this got to do with thermodynamic entropy?

Complexity and entropy are not unrelated. As the graph shows, maximal complexity happens at some medium entropy. See also the appendix in http://de.arxiv.org/abs/1703.08341

 

[Demystifier]

Was the Roman Empire at its peak a higher or lower entropy state for the Mediterranean region than how it existed a thousand years later or a thousand years before?

The entropy of the Roman Empire and its environment increased with time during its entire evolution.

Aren't you just using entropy as a metaphor rather than a scientific term with a precise meaning?

I'm not.

Also, using the precise term, is not the collection of cells in my body is a lower entropy state than a similar number of unicellular organisms in some primordial sea?

It's the wrong question. One should not count entropy of the cells alone, but entropy of cells and their environment, because cells cannot live without their environment. When counted that way, the primordial entropy was lower than the entropy now. Up to some point, the growth of entropy helps to build complexity.

Here is another picture that makes all this idea of the relation between entropy and complexity intuitive:

 

[BWV]

The entropy of the Roman Empire and its environment increased with time during its entire evolution.

OK, using my naive layman's understanding as the number of potential states of a system,

A) where all the political power in a region is concentrated in one system (say Emperor Trajan in 100AD)

have fewer states, analogous to the concentration of heat in a small portion of a solution compared to diffused political power / societal structure in the situation in Mediterranean in either 900BC or 1100 AD?

It's the wrong question. One should not count entropy of the cells alone, but entropy of cells and their environment, because cells cannot live without their environment. When counted that way, the primordial entropy was lower than the entropy now. Up to some point, the growth of entropy helps to build complexity.

Here is another picture that makes all this idea of the relation between entropy and complexity intuitive:

OK, so we are lower entropy than a similar mass of blue-green algae, but our lower entropy is more than offset by the increase in entopy we cause in our environment, correct?

 

[DEvens]

The entropy of the Roman Empire and its environment increased with time during its entire evolution.

Um... I detect a "deepity."

https://www.theguardian.com/lifeandstyle/2013/may/25/change-your-life-life-deepities-oliver-burkeman
Depending on how you define "its environment," I think you'd find that pretty difficult to back up with numbers. If you define it as "the entire universe" then yes. But if you defined it as, for example, within 1000 km of Rome, you'd find that a tough row to hoe indeed. The entropy changes during a single large thunderstorm are likely to swam any effects that might be going on in human activities during the ancient Roman era.

Your pictures of mixtures in glasses is really misleading. The idea of "complexity" is a notoriously difficult concept to quantify. Is a mixture with details smaller than the unaided eye can detect really less complex than a mixture with 1 mm scale lumps? That is by no means clear. Does adding raisins to bread dough make it more or less complex? That's not a simple question to answer.

Entropy is only extremely vaguely connected to complexity. On a macroscopic scale the best thing to think of entropy as is $dS = \frac{\delta Q}{T}$. That is, it's heat transferred divided by temperature. On a microscopic scale it's related to the degeneracy of a state, meaning the number of distinct configurations with the same energy. This is really not what we think of as complexity.

 

[jbriggs444]

But if you defined it as, for example, within 1000 km of Rome, you'd find that a tough row to hoe indeed

But no one with a serious understanding of thermodynamic entropy would consider defining an environment that excludes the most significant thermodynamic flows in and out of Rome. To whit, sunlight and dark skies.

 

[Demystifier]

OK, so we are lower entropy than a similar mass of blue-green algae, but our lower entropy is more than offset by the increase in entopy we cause in our environment, correct?

Right.

 

[Demystifier]

Depending on how you define "its environment," I think you'd find that pretty difficult to back up with numbers. If you define it as "the entire universe" then yes. But if you defined it as, for example, within 1000 km of Rome, you'd find that a tough row to hoe indeed. The entropy changes during a single large thunderstorm are likely to swam any effects that might be going on in human activities during the ancient Roman era.

By environment, I mean that part of environment that is essential for life. In particular, the sun light. The sun produces energy with a relatively low entropy, while living beings turn a part of this energy into a heat with much larger entropy. For more details, including some numbers, see R. Penrose, The Emperor's New Mind, Chap. 7.

 

[Demystifier]

Um... I detect a "deepity."

I've just learned a new word, thanks!