Recent content by andrebourbaki

Hilbert's Sixth Problem now (essentially) solved A common misconception is that Kolmogoroff solved the part of Hilbert's problem related to probabilities. This misconception was not shared by Kolmogoroff! He well knew that axiomatising the purely mathematical theory of probabilities was merely...

entropy, disorder, and dispersion thermodynamic entropy is a precisely defined concept. Informational entropy is a statistical mechanics concept of entropy, first introduced by Boltzmann, refined by Gibbs, and re-discovered and applied to wider fields by Shannon, and is a concept that seems to...

Lambert's woolly "definition" of entropy Prof. Lambert is just confused. As an educator, he has found a distorted, simplified presentation that makes things easier for his students, but in fact it is in itself even more confused than anything he criticises about "disorder". He switches...

Quite right. But for some reason I was looking at Einstein's original papers the other day. Did you know he sometimes calls the Christoffel symbols « components of the gravitational field », sometimes the metric is called « gravity », and sometimes the curvature is called « the expression of...

Gravity is not a force. What is a force, anyway? Newton clarified for almost the first time in Science what a force is: First I will say it, then explain it: A force is something which makes the motion of a body deviate from uniform straightline motion. Newton pointed out that bodies have a...

Collected Papers of Albert Einstein suppl. (translations) volume 6, p.120 Not directly on point, but here is Einstein being very categorical about a relatied point: « which makes space-time coordinates into physically meaningless parameters ». p. 156 « Thus, according to the general theory of...

First of all, if a physicist casually uses the word « force » when really concentrating on something else, this is not strong evidence that they thought gravity was a force *as opposed to* a pseudo-force. So Einstein and others may sometimes talk as if they thought gravity was a force, but this...

Someone will, I hope, correct me if I am wrong, but the current state is different than the perihelion of Mercury and the Stefan-Boltzmann paradox, back before the GR rev and the Quantum rev. What you refer to is stubborn (although small) experimental facts. But at present what we have...

>People build theories based on the observations they make in the macro world. The existing theories, from QM to the Standard Model, and GR by itself, are all, as you say, based on macroscopic observations. We observe (in 1900) the spectral lines of Hydrogen, and after a lot of ingenious...

Feynmans' opinion about the Axioms of quantum mechanics `We and our measuring instruments are part of nature and so are, in principle, described by an amplitude function [the wave function] satisfying a deterministic equation [Schrodinger's equation]. Why can we only predict the probability...

Is this a concession that there is an experimentally replicable regularity and no conceivable physical theory can predict it or explain it or even, it seems you go this far, even describe it? For the rest, your assertions are mostly philosophy, which is not quite the thing to discuss in this...

To recap, your part 1, from posts 97 and 101, is the usual axioms of QM (or any theory), which is mathematics. Your part 2 gives physical names to some of those maths concepts. Part 3 is a provisional, subject to improvement, list of correspondences: to the name of each quantum...

clocks do not perform quantum measurements In the posts in which Fredrik discusses his projected systematisation of the part of physical theory which is not yet tidy, the correlations between quantum observables and physical measurement devices (and procedures of state preparation as well, I...

It brought about much more clarity than had been present before. It is not supposed to make Quantum Mechanics conform to our classical intuition! Historically, it had a great influence on our understanding of entanglement. Because von Neumann had axioms to work with, he tried to prove that a...

A point by itself is not a singularity. It is always some function on the surrounding space that has a singularity at that point...(or, of course, doesn't). We talk quickly and sloppily of a point as being a singularity and this may have misled you but if you look at the context, there is...