The "Second Law of Thermodynamics" plays a common role in debates regarding evolution and creationism, but mostly because supporters of creationism don't understand what it means, even though they really think they do. If they understood it, they'd realize that far from conflicting with evolution, the Second Law of Thermodynamics is completely consistent with evolution
According to the Second Law of Thermodynamics, every isolated system will eventually reach "thermal equilibrium," in which energy is not transferred from one part of the system to another. This is a state of maximum entropy where there is no order, no life and nothing happening. According to creationists, this means that everything is gradually running down and, hence, science proves that evolution cannot happen. How? Because evolution represents an increase in order, and that contradicts thermodynamics.
What these creationists fail to understand, however, is that there are two key words in the above definition: "isolated" and "eventually." The Second Law of Thermodynamics only applies to isolated systems - to be isolated, a system cannot exchange energy or matter with any other system. Such a system will eventually reach thermal equilibrium.
Now, is the earth an isolated system? No, there is a constant influx of energy from the sun. Will the earth, as part of the universe, eventually reach thermal equilibrium? Apparently - but in the mean time, portions of the universe do not have to constantly "wind down." The Second Law of Thermodynamics is not violated when non-isolated systems decrease in entropy. The Second Law of Thermodynamics is also not violated when portions of an isolated system (as our planet is a portion of the universe) temporarily decrease in entropy.
Abiogenesis and Thermodynamics
Aside from evolution generally, creationists also like to argue that life itself couldn't have arisen naturally (abiogenesis) because that would contradict the second law of thermodynamics law well; therefore God must have created life. Put simply, they argue that the development of order and complexity, which is the same as a reduction of entropy, cannot occur naturally.
First, as was already pointed out above the Second Law of Thermodynamics, which limits the ability of a natural system to have a decrease of entropy, only applies to closed systems, not to open systems. The planet Earth is an open system and this allows life to both start and to develop.
Ironically, one of the best examples of an open system decreasing in entropy is a living organism. All organisms run the risk of approaching maximum entropy, or death., but they avoid this for as long as possible by drawing in energy from the world: eating, drinking, and assimilating.
The second problem in the creationists' argument is that whenever a system experiences a drop in entropy, a price must be paid. For example, when a biological organism absorbs energy and grows