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Life and entropy

  1. Aug 1, 2010 #1
    Is life an example of extremely low-entropy system? Why? Could someone tell me more about that?

    (I know it depends on the way I define life, but I mean in general, we all know what does life mean)

  2. jcsd
  3. Aug 1, 2010 #2
    Well, I would say yes. Biosphere is unbelievably complex system of self-organized entities - low entropy, to say it in other words. This, of course, is not violation of the 2nd Law - Earth is being fed with solar energy which is re-emited as infrared radiation. This reemited radiation has much larger entropy than incoming solar radiation because approximately same amount of energy is re-radiated in different spectra - with much larger number of photons, let's say.
  4. Aug 1, 2010 #3
    The average human body eats and metabolizes (oxidizes) plant food produced by photosynthesis (or eats animals who consume plants), and radiates heat at the rate of ~100 watts (= 2000 kiloCalories per day). This heat is the lowest form of waste energy, so entropy has to increase. So life increases entropy, one bite at a time.

    Bob S
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