I was discussing the second law argument with a scientist friend the other day, and mentioned that the second law is sometimes called the “common sense law of physics”. This morning he wrote:
Yesterday I spoke with my wife about these questions. She immediately grasped that chaos results on the long term when she would stop caring for her home.
Tell your wife she has made a perfectly valid application of the second law of thermodynamics. In fact, let’s take her application a bit further.
Suppose you and your wife go for vacation, leaving a dog, cat and a parakeet loose in the house (I put the animals there to cause the entropy to increase more rapidly, otherwise you might have to take a much longer vacation to see the same effect). When you come back, you will not be surprised to see chaos in the house. But tell her some scientists say, “but if you leave the door open while on vacation, your house becomes an open system, and the second law does not apply to open systems…you may find everything in better condition than when you left.”
I’ll bet she will say, if a maid enters through the door and cleans the house, maybe, but if all that enters is wind, rain and other animals, probably not.
This is an application of the main point in chapter 5 of my new book : “If an increase in order is extremely improbable when a system is closed, it is still extremely improbable when the system is open, unless something is entering that makes it NOT extremely improbable.”
For a slightly more technical version of this story, complete with a mathematical analysis of the equations for entropy change, see my video .
(For those who don’t watch the video, or give up on it before the end, and thus don’t understand what this story has to do with evolution, I should include the punch line):
If we found evidence that DNA, auto parts, computer chips and books entered through the Earth’s atmosphere at some time in the past, then perhaps the appearance of humans, cars, computers, and encyclopedias on a previously barren planet could be explained without postulating a violation of the second law here. But if all we see entering is radiation and meteorite fragments, it seems clear that what is entering through the boundary cannot explain the increase in order observed here.