Evolution and Thermodynamics ```Name: Mike Spanel Status: N/a Age: N/A Location: N/A Country: N/A Date: Around 1993 ``` Question: My friend stated that the first and second laws of thermodynamics contradict the theory of evolution. Also what are stated in the first and second laws of thermodynamics? Replies: Your friend is wrong, but he /she is in good company. A lot of people misunderstand thermodynamics and think that they contradict the theory of evolution. Here are some basic definitions: The First Law: Heat put into a system + work done on a system = increase in internal energy of the system, or dQ + dW = dU. This is just conservation of energy; if you take a system and heat it, and do work on it, you will increase its internal energy. The Second Law: If a system is changed by doing work on it or by heating/cooling it, the entropy will either increase or stay the same. Notice that in the above definitions, I have not yet said what a "system" is. The main thing to remember is that although the total entropy of a system must increase or stay the same, local fluctuations can be positive or negative. For example, by cooling water, we can make ice. Water, a liquid, has a higher entropy than ice, a solid. So by freezing water we DECREASE the water's entropy. Therefore, it is possible to raise or lower the entropy of a system, as long as it is an OPEN system (one that can exchange energy with its surroundings). The earth is an open system, and so is a biological system (like a frog or an ape). So evolution does NOT violate thermodynamics. Robert Topper Click here to return to the Physics Archives

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