Gabriele Carcassi on Why Statistical Mechanics is Fundamental in Physics

Spoiler:

See Assumptions of Physics Reading Group and Sabine Hossenfelder on The Laws of Physics. 

My comment:

12:06 So there is another view that could be given here which is tracing the historical developments that resulted in this difference. Presumably they are several and occurred at different stages of the development of the theory. Was the matrix (Heisenberg) versus wavefunction (Schrödinger) picture one of them? See nLab picture of mechanics:

For example, these terms included also Schrödinger's use of typically wave-like functions as pure states (and correspondingly operators in the higher-type-theoretic sense as observables) vs Heisenberg's use of infinite-dimensional matrices as observables (and correspondingly infinite sequences as pure states). ... This is entirely separate from the question of whether states or observables are taken to evolve with time. Still, there is this connection: Schrödinger evolved states, and his approach was called ‘wave mechanics’ after his representation for states, while Heisenberg evolved observables, and his approach was called ‘matrix mechanics’ after his representation for observables.

In teaching this at undergraduate level the idea seems to be that these two pictures are essentially the same, and Schrödinger's is whackier, so they teach that. See Jorge Diaz on Heisenberg's Über quantentheoretische Umdeutung kinematischer und mechanischer Beziehungen. 

For more on thermodynamics and observation, see Gabriele Carcassi on The Correspondence Between Quantum and Classical Mechanics and Emily Riehl and Terrence Tau on The Future of Mathematics. 

You can donate to support this project: https://assumptionsofphysics.org/donate/. 

Subscribe to Gabriele Carcassi. 

Unfortunately Cosmology is considered a branch of physics now, because certain observations are considered experimental even though they are results of an experiment that was only imagined to have been conducted once, a few billion years ago, before there were any observers and which will never be observed again, or so we hope. Listen to Brian Keating at 42:17 to hear what you have to do to be able to observe these events with sufficient fidelity to get a significant result. At 52:34 they get to say what they think is the problem. The problem seems to be that if you suggest to a Cosmologist that they might be extrapolating a laboratory result beyond the realm of it's reasonable applicability, vis that the blackbody spectrum is experimentally observed in a laboratory only in certain condensed states of matter and that it is in fact dependent on the particular properties of the condensed matter which the body is made from, then you are bringing into doubt that the Universe might not have been much hotter and much denser in the past than it is now. 1:01:37 Keating just doesn't see that it is a problem that the hypothesis that the state of the Universe to which the blackbody radiation law is being applied is not one of those on which the empirical evidence for the theory is based. 1:04:20 It seems pretty clear to me what the objection is, and that Keating simply doesn't want to admit it. I personally think that Cosmology, the sort that Keating does, is not a science. The point where he lost the argument was when he accused them of hubris.

Subscribe to DemistifySci.