Question

The present state of the Earth, with biological prosperity, seems to be much further from an equilibrium state than the original state of molten rocks and hot gases

(a) Is the evolution of life a violation of the second law of thermodynamics? parts (b) and (c) may help you in answering part (a)...

(b) If one build a big shiny steel sphere around the earth, at a distance half the way to the moon, what would happen on earth?

(c) If one build a big shiny steel sphere around the Earth, at a distance a bit larger than Mars, what would happen on Earth?

Answer 1

(a) The second law of thermodynamics states that the entropy of a closed system tends to increase with time. Entropy can be understood as the equivalent of disorder in layman's terms. The important point to be noted here is that the second law of thermodynamics holds true only for closed systems. The Earth is not a closed system; it continually receives energy via radiation from the sun.

But the universe in itself, is an isolated system as it includes any possible system and its surroundings. In such a system, the entropy change of a reversible process is always zero. On the other hand, in all irreversible processes of an isolated system, the entropy of the system and its surroundings increases.

Now, the idea of evolution is that genetic mutations can occur eventually which leads to the possibility of individual organisms possessing traits different from that of its predecessors. It is also possible that these mutations can be random. So, this would lead to an increase in entropy only if they occurred in a closed system, but as already stated, the Earth isn't a closed system. Thus, evolution does not take place in a closed system, rather, it involves the influence of environmental factors and external forces for natural selection as well.

So, the evolution of life is not a violation of the second law of thermodynamics.