Why isn't the entropy of the earth increasing?

Scythian’s answer is good, but it is useful to amplify some points and correct some others. First of all – without a doubt, the entropy of the crust, the oceans and the atmosphere is dominated by the presence of a nearby star that is spewing energy our way at a stupendous rate in the form of photon energy packets that are very much larger than the photon energy packets the earth emits back into space. We live off a steady rain of high energy photons (mostly UV and visible) that the earth radiates back into space with with wavelengths well into the infrared. Since the energy influx and outgo are basically balanced over all but the geologic time scales (the Sun has been slowly brightening for a couple of billion years), just keeping track of the wavelengths of the incoming and outgoing radiation to and from earth demonstrates that earth isn’t “thumbing its nose” at thermodynamics – it is very much the opposite: earth is a planet-sized device for producing entropy.

The second law of thermodynamics is basically about the distribution of energy – over time, energy is distributed in the most probable way. The “most probable way” spreads energy out. When energy is concentrated in one place it spreads out over time. The net energy balance of earth is achieved by gobbling up a lot of photons in the 2 – 10 nm (1.25 – 6 eV) range and emitting it in the 0.025 – 0.125 eV range. In other words, 20 – 30 photons out for every photon in. That’s “spreading the energy out”. The appearance of “order” in human activities and in life itself – as Scythian indicated – is of virtually no importance in the grand scheme of things. Photosynthetic organisms act as middlemen in divvying up the photon’s energy, and we who eat them chop their chemically stored energy up like the energy parasites we are. Evolution? Irrelevant. Thermodynamic entropy is a measurable quantity – no biochemical process – including all the processes involved in natural selection – fails to increase entropy. We enable the second law – we’re just too conceited to admit it.

Your question about boiling freon presents no predicament. First – define “this system”. Since your sealed glass bottle is being driven by heating from the sun – you’ve got to account for the sun in evaluating the change in entropy.

EDIT: Just as a matter of terminology – if you are willing to leave light out when considering exchange of matter, the earth is reasonably well approximated as a closed system (aside from the occasional incoming meteor, space dust, and escaping helium gas), but it isn’t an isolated system. That is why FGR’s freon jar analogy is appropriate, but comparison to a system in which a fluid “flows through the system” is not, since that would be an open system. One more P.S.: I overstated above in writing 40 – 50 photons out – it should be as it now is: 20 – 30 photons out.

Source(s): http://en.wikipedia.org/wiki/Thermodynamic_system1

The first example is just the result of observation. It does not make the Bible the word of god. The second example is just an application of the first example. It also does not make the Bible the word of god. According to the Bible the earth is a flat, immovable disk. You Bible believers burned Giordano Bruno at the stake for saying the earth moves, and you would have done the same to Galileo if he had not recanted. So how do you square that? Added: Nebuchadnezzar’s vision in Daniel 4:10-11 makes it clear that the earth is flat, and Daniel states in 2:28 that the visions of Nebuchadnezzar are from God. There are also numerous other passages in the Bible indicating that the earth is flat and not one indicating it is a sphere. The Hebrew word translated as circle means just that, not sphere. The physical aspect of a circle is a disk. Added: Read Isaiah 40:38. Is it saying that god created a figure of speech? A sphere does not have ends. A disk does: its rim. Also check out Job 38:12-13 and Deut 28:64, and numerous other such passages. Added: By the way, the law of increasing entropy is actually the Second Law of Thermodynamics, which really doesn’t apply to the things you mentioned. The Second Law states that the net available energy cannot increase in a closed system. It also states that any process that occurs in a closed system will result in less available energy. The degree of the non-availability of energy in a system is called its entropy. The greater the nonavailability of energy in the system the greater the entropy. You should try learning a few things about the subject before you ask questions relating to it.

Thanks for the thought provoking question, First Grade.

First off, the mere presence of what we perceive as “order”, in the the form of life, does not necessarily imply a decrease in the total entropy of earth. In fact, most (if not all) “self-organizing processes” result in an increase in entropy.

Secondly, and more importantly, the Earth is nowhere close to a closed system, so the Second Law does not apply. Energy can both enter and leave the Earth.

The largest net source of energy, at least at the surface of the earth, is sunlight, while the net sink of energy is blackbody radiation out to space. The difference is that the average frequency of sunlight is much higher than the average frequency of radiated heat from the earth. Hence sunlight has a lower effective entropy than the earth’s radiated heat (per Max Planck…) So, it’s possible for the net entropy of the earth to decrease.

EDIT:

The entropy of earth CANNOT be construed to be a constant or even at a local maximum. See my second paragraph.

Note that in practice the total entropy of the *entire planet* varies little, due to it’s immense mass and heat capacity; however the entropy of just the earth’s surface and the atmosphere can vary significantly.

Are we talking about thermodynamic entropy or Shannon entropy? Too many people confuse the two, believing that appearance of “order” defies the 2nd Law of Thermodynamics, and that everything must necessarily progress into apparent “disorder”. The 2nd Law of Thermodynamics makes no such claim, as much so many people want to believe that. What counts is that TOTAL thermodynamic entropy inexorably rises, even though it may APPEAR to us that a lot of order and complexity seems to be spontaneously arising. As an example, if I have a deck of cards, shuffle them, and lay the cards up spread out on the table, seeing the cards to be random, and then I rearrange the cards so that they are all in perfect sequence, has thermodynamic entropy gone down? No, it has not. If very carefully measured, the total thermodynamic entropy has actually gone up—the sequence of the cards plays no role at all in the total thermodynamic entropy. This fine point is lost on a lot of people. The plain fact is, by far the greatest contributor to the total thermodynamic entropy of the earth comes from its sheer internal mass at an almost stable temperature, albeit cooling very very slowly (because it is radiating heat out into space, a consequence of the fact that Earth is not a closed system). What goes on the surface of the Earth, including this little ordered ditty that I’m writing up right now, has virtually no impact on this total thermodynamic entropy of the Earth. In fact, my mere thinking about what to write down is adding to the overall entropy.

See the links for a quickie 2-page derivation of the thermodynamic definition of entropy from statistical mechanics. In particular, note the conditions to be met at the beginning of the derivation.

Edit: ty, mdGreg C

Edit 2: You speak of a “concealed” bottle with a paddlewheel inside. It’s obviously not a closed system, since it allows radiative influx and heat escape. As a matter of fact, chemical process engineers routinely consider a small volume of fluid travelling through a system, and compute the rise and fall of its total entropy. No suprise to such engineers that it could do that.

Edit 3: Here’s another experiment that can and has been done: Fill a jar with various sized sand and pebble, and shake it continuously by apparatus that is able to vary both amplitude and frequency. The sand and pebble can be made to separate into layers or made to mix up thoroughly, even as it is being shaken continously. What do we say about the entropy of this? Many people still insist that entropy is varying dramatically, “by design” of the persons controlling the apparatus, or at least by persons who built the apparatus. No such dramatic rise and fall in entropy is occuring as it is being shaken continuously. The entropy is very nearly constant, even though the changes in appearance can be dramatic.

Source(s): http://i254.photobucket.com/albums/hh120/Scythian1…

http://i254.photobucket.com/albums/hh120/Scythian1…1

Entropy of the whole system is increasing. This includes the sun, which is burning through its hydrogen. It includes the tidal effect, which is degrading as the moon moves further out in orbit. It also includes the nuclear fission in the Earth’s core, which will diminish as fissile material is consumed. These are the energies that drive Earth (including life), and one day they will run out.

Source(s): That’s my guess any way. Not an entropy expert.

Nice Scyth.