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Entropy and Time February 20, 2009

Posted by mcw5247 in Metaphysics, Philosophy of physics.

The Second law of Thermodynamics states that a closed system will never decrease in entropy. That is to say, that the energy of a given system will never spontaniously increase. Ludwig Bolzmann worked with this idea as well as developing a statistical approach to describing how gas molecules interact within a closed container. From his work with this Boltzmann began developing his view on the arrow of time.

His ideas began with watching the gasses interact, and seeing that they always move to the highest entropy state given enough time. He stated that he believed time could only move in one direction, forward. His evidence for this was to give examples of what he called irreversible events, which are things such as air leaking from a baloon or a hot liquid cooling off at room temperature. These are events that always happen in one direction and never the other, and he claimed that this was a proof of how time could only flow forward.

From this idea, one can pose the question of how the universe can be sustaining an increase in entropy over a very long period of time. One response to this is the low entropy early universe, which is to say that shortly after the universe formed all of the matter within it was evenly distributed. This would have been a very low entropy state for the universe to be in and would thus allow for entropy to increase over a long period of time.

Through argument, Boltzmann later refined his ideas, and finally came to his entropy curve discussion. Here he said that it was possible for entropy to be a constant when looked at over a long enough period, and that we could merely be on a fluctuation of this where it appears to us that entropy always increases. This idea is disturbing however as many of our laws depend on how we currently view entropy.

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