…does not imply Causation

Episode 31, in which Welcome to Nightvale wrestles with the philosophy of science:

…and it is definitely something; and definitely weird. I’m not sure how it got here, but I’m not sure how I got here either. Causation is difficult and confusing…When something is this weird, one shouldn’t assume to understand anything specific about it at all.
Welcome to Nightvale, Episode 31: “A Blinking Light up on the Mountain”

Maxwell’s Demon, Boltzmann’s H theorem, Ergodicity and other awesome stuff

I just discovered this treasure trove on the foundations and history of statistical mechanics:

Compendium of the foundations of classical statistical physics, by Jos Uffink (PDF)

The abstract:

Roughly speaking, classical statistical physics is the branch of theoretical physics that aims to account for the thermal behaviour of macroscopic bodies in terms of a classical mechanical model of their microscopic constituents, with the help of probabilistic assumptions. In the last century and a half, a fair number of approaches have been developed to meet this aim. This study of their foundations assesses their coherence and analyzes the motivations for their basic assumptions, and the interpretations of their central concepts. The most outstanding foundational problems are the explanation of time-asymmetry in thermal behaviour, the relative autonomy of thermal phenomena from their microscopic underpinning, and the meaning of probability.

A more or less historic survey is given of the work of Maxwell, Boltzmann and Gibbs in statis- tical physics, and the problems and objections to which their work gave rise. Next, we review some modern approaches to (i) equilibrium statistical mechanics, such as ergodic theory and the theory of the thermodynamic limit; and to (ii) non-equilibrium statistical mechanics as provided by Lanford’s work on the Boltzmann equation, the so-called Bogolyubov-Born-Green-Kirkwood-Yvon approach, and stochastic approaches such as ‘coarse-graining’ and the ‘open systems’ approach. In all cases, we focus on the subtle interplay between probabilistic assumptions, dynamical assumptions, initial conditions and other ingredients used in these approaches.

This will keep me busy.

Best letter response. . .EVER

Charles Bennett has a beef with the wording of an article title in Science“At long last, Gravity Probe B satellite proves Einstein right”.

I find myself frequently repeating to students and the public that science doesn’t “prove” theories. Scientific measurements can only disprove theories or be consistent with them.

Instead of going on about the philosophy of science at length, let’s just quote the spot-on quote from their response:

Bennett is completely correct. It’s an important conceptual point, and we blew it.



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