Richard Feynman on Boltzmann Brains

[n2doc]

The Boltzmann Brain paradox is an argument against the idea that the universe around us, with its incredibly low-entropy early conditions and consequential arrow of time, is simply a statistical fluctuation within some eternal system that spends most of its time in thermal equilibrium. You can get a universe like ours that way, but you’re overwhelmingly more likely to get just a single galaxy, or a single planet, or even just a single brain — so the statistical-fluctuation idea seems to be ruled out by experiment. (With potentially profound consequences.)

The first invocation of an argument along these lines, as far as I know, came from Sir Arthur Eddington in 1931. But it’s a fairly straightforward argument, once you grant the assumptions (although there remain critics). So I’m sure that any number of people have thought along similar lines, without making a big deal about it.

One of those people, I just noticed, was Richard Feynman. At the end of his chapter on entropy in the Feynman Lectures on Physics, he ponders how to get an arrow of time in a universe governed by time-symmetric underlying laws.

So far as we know, all the fundamental laws of physics, such as Newton’s equations, are reversible. Then were does irreversibility come from? It comes from order going to disorder, but we do not understand this until we know the origin of the order. Why is it that the situations we find ourselves in every day are always out of equilibrium?

more:
http://blogs.discovermagazine.com/cosmicvariance/2008/12/29/richard-feynman-on-boltzmann-brains/

[Mike 03]

1. Wonderful post. I miss being able to concentrate on his insights and these issues

but it is so awesome to see them discussed here.

Thank you.

Rec.

[Mnemosyne]

2. 'Surely You're Joking, Mr. Feynman!' - Another great mind gone. n/t

[truedelphi]

3. That's exactly what I was trying to say just the other day!!

Kidding aside, I love Feynman and wish all physicists had his quirk for being human, humane, understandble etc.

[Manifestor_of_Light]

4. One of the Studmuffins of Physics.

There were three in 20th century physics.

First one was Einstein.

Second one was Feynman.

Third one was Sagan.




You'd never know I'm a girl who loves science and engineering nerds, would ya???? :D

[Catshrink]

6. Another was Rutherford

Although he won the Nobel Prize for Chemistry, he always considered himself to be a physicist. He and Einstein had great respect for each other -- Einstein was the theoretician while Rutherford was the experimenter.

[phantom power]

5. Scientific American had an article on that sort of cosmology last year.

We inhabit a period (and locale) of temporary non-equilibrium. Previous cosmi are not causally accessible to us, due to the huge distances in space and time between periods of non-equilibrium.