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posted by martyb on Tuesday May 06 2014, @02:32PM   Printer-friendly
from the second-chances-come-first dept.

Thought experiment proposed to reconcile psychological versus thermodynamic arrows of time:

A pair of physicists has proposed a thought experiment to help reconcile the seeming disparity between the psychological and thermodynamic arrows of time. In their paper published in the journal Physical Review E, Leonard Mlodinow and Todd Brun claim their thought experiment demonstrates that the two seemingly contradictory views of time, must always align.

When ordinary people think about time, they see the past as something that has come before and the future as a great unknown yet to come. We can remember the past, because it has happened already, but not the future, because it hasn't. Physicists, on the other hand see time as able to move either forward or backwards (towards greater entropy), which implies that we should be able to remember events in the future. So, why can't we?

It's because of the way our memories work the two say, and they've created a thought experiment to demonstrate what they mean. Imagine, they write, two chambers connected by an atomic sized tube with a turnstile in it. If there is gas in one of the chambers, individual atoms of it will move through the tube to the other chamber (towards higher entropy) tripping the turnstile as they go, in effect, counting the atoms as they pass by, until both sides have equal numbers of atoms-creating a state of equilibrium.

http://phys.org/news/2014-05-thought-psychological -thermodynamic-arrows.html

Arrow of Time FAQ

http://physics.aps.org/articles/v7/47

http://journals.aps.org/pre/abstract/10.1103/PhysR evE.89.052102

 
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  • (Score: 1) by boristhespider on Tuesday May 06 2014, @10:11PM

    by boristhespider (4048) on Tuesday May 06 2014, @10:11PM (#40362)

    The word "observer" has caused more misunderstandings than most other things in 20th century physics. It was originally used because quantum mechanics was heavily based on the laboratory -- when Heisenberg formulated his version of quantum mechanics, his first step was literally to take the observables one could recover in a lab and then play around with them to find how they were related given some theoretical modifications he'd made to classical mechanics; it was only later someone (Jordan, perhaps?) pointed out to him that he was doing matrix multiplication. So it made perfect sense to talk about an "observer". Unfortunately the name stuck, and has created unnecessary misunderstandings since. If you replace the word "is observed by" with "interacts with" then you're suddenly free of this disturbing anthropomorphism of nature, without changing the theory at all.