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Re: [Phys-l] Arrow of Time Issue



Could you explain to me why entropy can decrease (without stating the work (ie that experiment just mentioned) of someone else?



On Mar 8, 2012, at 10:25 PM, Bernard Cleyet <bernardcleyet@redshift.com> wrote:


On 2012, Mar 08, , at 20:07, carmelo@pacific.net.sg wrote:

Denis Evans from Australian National University measured changes in
the entropy of latex beads, each a few micrometres in size and
suspended in water. By using a precise laser beam, the team measured
the movement of the beads very frequently, and hence repeatedly
calculate the entropy of the system at short time intervals. They
found that the change in entropy can be negative over time intervals
of a few tenths of a second. In a sense, entropy can be violated in
isolated system…


Alphonsus

Quoting John Mallinckrodt <ajm@csupomona.edu>:

Another way of saying the same thing. The second law of
thermodynamics says that the entropy of isolated systems "does not
decrease with time." If we discovered in experiments that the
entropy of isolated systems "decreases with time," it would mean
that the second law of thermodynamics is wrong, NOT that time is
running backwards.

John Mallinckrodt
Cal Poly Pomona



Perhaps John refers to macroscopic systems where such is rather unlikely. I understand on a micro. scale, molecules can "coalesce" to cause the scattering that results in the blu sky, no?


bc read G. Gamow as a child.
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