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A Moon reduces Earth's entropy?

  1. Feb 8, 2016 #1
    Spontaneous negative entropy reactions can occur when the internal energy decrease is greater than the negative dS*T. dG=dU-dST is spontaneous if dG is negative.

    The moon is receiving at least 1E8 J/s from the loss of rotational energy from the Earth's water and air. A lot more rotational energy is being lost from the mantle. This is a minimum because it assumes the core is slowing down as fast, which is not the case. Rotational energy is internal energy. This is a non-heat energy transfer, giving a negative change in Gibbs energy. This makes spontaneous negative entropy processes possible. It causes a reduction in the entropy of the distribution of matter on Earth, making the air, water, and mantle less homogeneous in distribution than they otherwise would have been. Is this a major source of the "neg-entropy" that life taps into? Could life have existed without the moon? Asimov said life could not have reached land and the moon itself without it.

    The Earth is putting the moon into a higher orbit, 3.78 cm per year (7.5E18 Joules/yr), at a larger cost in rotational energy, losing -15 microseconds on the clock every year. I calculate from this that heat from friction in the oceans and mantle from the moon slowing the Earth is less than 10 times the energy that lifts the moon. It depends on how the core is not slowing up as much as the mantle.

    Modern society depends heavily on the ores and veins the moon seems to have had a big part in concentrating (lower entropy) for more efficient access. Metals and metalloids are being created from the ores, seemingly on a path to replacing bone, muscle, and brains in the biosphere. Even the refined silicon metalloid is 20 times more efficient per area than photosynthesis. Oxygen is removed to create denser material. The resulting metals and metalloids (silicon) are less entropy per mole for that element, but taken as a whole with the CO2, there does not appear to be much of an entropy change. The gases would have to be captured in order to say it is lower entropy. Cement is harder to figure. But anything resulting in a denser material will usually mean lower entropy if there is not an increase in the gases.

    When talking about entropy and life, people usually just say 2nd law is not violated. But does the moon make it probable instead of merely possible? All known life increases entropy, which means there was a previous source of low entropy. How much did the collision that created the moon contribute to Earth's pre-existing low entropy state? Isn't a tilted axis a lower entropy compared to what is expected? It has contributed to life via seasons in the same way tides have. It does not cause more energy to enter the biosphere, so if life really benefits from it, must it be in the form low entropy? This would require life to eventually straighten the orbit if it is tapping into that low entropy. Aren't tides a lower entropy than expected by breaking the homogeneous mass distribution of water?

    Do open systems like Earth receiving light energy require an external force (like the moon) to create lower entropy? Open systems can result in lower local entropy due to the large excess entropy they can emits to the universe. The Universe "needs entropy to expand" because entropy on an expanding volume basis of the Universe is constant. (see Stephen Weinberg's classic "The First 3 minutes" that says this is a requirement of the standard model of the big bang) This mean on a rigid volume basis it lowers.

    Did the ancient collision cause us to "wake up"? Is our job to create lower local entropy as fast as possible, emitting the excess entropy to let the Universe expand away into a fundamentally un-observable nothingness?

    Selection is not a force. Genes are just the memory of what the environment found. Arguments over gene, individual, kin, and group selection are errant and non-physical, like the old mind-body discussions.

    To what extent is life the moon's snowflake?
  2. jcsd
  3. Feb 8, 2016 #2


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