Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

I How can thermal fluctuations decrease entropy?

  1. Apr 9, 2017 #1
  2. jcsd
  3. Apr 9, 2017 #2

    jfizzix

    User Avatar
    Science Advisor
    Gold Member

    That the entropy of a closed system cannot spontaneously decrease is a statement of probability rather than about dynamics.
    The laws governing how particles collide and interact are reversible in time, so all processes that can happen, can also happen in reverse.
    However...
    The relative probability of some processes happening in reverse are so small as to be unprecedented in the history of the universe, say, like air spontaneously rushing to one side of a room, leaving the other side in near vacuum.
    That said, microscopic changes in air pressure can and do happen.
    These thermodynamic fluctuations are extremely small relative to the macroscopic properties of the system.
    Though the probability of a large (enough to see) fluctuation is small, the probability of a small fluctuation is large.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: How can thermal fluctuations decrease entropy?
  1. Entropy decrease (Replies: 6)

  2. Entropy Decreases? (Replies: 8)

Loading...