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7:30 pm, Wednesday, April 9, 2008
Fairmont Social Lounge, St. John's College
Time's Arrow and Boltzmann Entropy
Joel L. Lebowitz
Rutgers University
In the world about us, the past is distinctly
different from the
future. Milk spills but doesn't unspill; eggs splatter but do not
unsplatter; waves break but do not unbreak; we always grow older,
never younger. These processes all move in one direction in time -
they are called "time-irreversible" and define the Arrow of Time. It
is therefore very surprising that the relevant fundamental laws of
nature make no such distinction between the past and the future.
This in turn leads to a great puzzle - if the laws of nature permit
all processes to be run backwards in time, why don't we observe them
doing so? Why does a video of an egg splattering run backwards look
ridiculous? Put another way: how can time-reversible motions of
atoms and molecules, the microscopic components of material systems,
give rise to the observed time-irreversible behavior of our everyday
world?
I will describe the resolutions of this paradox due to Maxwell,
Thomson and (particularly) Boltzmann, in classical physics. I will
also discuss newer developments in both classical and quantum
settings.
Find out more
by visiting his website.
Additional resources for this talk:
slides.
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