Question

why the entropy of earth increases ?

Answer 1

This flow of energy to Earth is in the form of photons with peak energy in the region of visible light.  The Earth maintains a nearly stable temperature by radiating infrared energy.  Since each infrared photon has a lot less energy than each visible light photon, far more photons leave the Earth than are absorbed in any given time.

But photons are also associated with entropy.  It turns out that the amount of entropy per photon is completely independent of photon energy.  This result was derived separately in two peer reviewed papers published in or about 2002.  I had derived the same result before reading these papers.

The production of photons increases entropy in proportion to the number of photons produced.  The sun alone producing photons increases entropy, and since the sun produces far more photons than it sends to the Earth, this alone indicates that the Entropy of the solar system, including the Earth, is increasing.  But what if you're only interested in the Earth as a system?

There are some who argue that the absorption of light from the sun by the Earth reduces entropy.  This isn't correct, but for the sake of argument, assume it is.  This hypothetical entropy reduction is much smaller that the entropy increase from photons produced to radiate from the Earth.  Thus, no matter how you look at the sun, the Earth, the two together or the entire solar system, entropy is increasing.  All stars act to increase entropy at rapid rates.

BTW, there was also a paper published in possibly 2003 that calculated entropy changes associated with Earth absorbing and emitting radiation based on thermodynamics without using the fact that entropy increases from photon production depend only on the number of photons.  It got exactly the same result as if they had started with this fact about photons and entropy!

Answer 2

Biological evolution of life on Earth, from simple prokaryote-like cells to large, multicellar eukaryotic organisms, A) has occurred in accordance with the laws of thermodynamics. B) has caused an increase in the entropy of the planet. C) has been made possible by expending Earth's energy resources.Jan 27, 2015