I have heard that Christians use the second law of thermodynamics as an argument against evolution.
The second law of thermodynamics expresses the existence of a quanity called the entropy of a system and states that the entropy of an isolated macroscopic system never decreases, or, equivalently, that perpetual motion machines of the second kind are impossible. (Wikipedia.)
An atheist's response was that it only applies to a closed system. So then what is the validity of this argument, to argue against evolution? What does the atheists point of view have to do with its validity? Does it only apply to a closed system?