Ciro Santilli @cirosantilli 37

Good phylogenetic tree as usual: en.wikipedia.org/w/index.php?title=Animal&oldid=1053478004#Phylogeny

Some people have been creating YouTube channels that just post and go over a large number of Stack Exchange questions, some of them with a quick random intro video. Perfectly legal due to CC BY-SA but really weird stuff!

Likely the best JavaScript 2D game engine as of 2023.Uses Matter.js as a physics engine if enabled. There's also an alternative (in-house?) "arcade" engine: photonstorm.github.io/phaser3-docs/Phaser.Physics.Arcade.ArcadePhysics.html but it appears to be simpler/less robust (but also possibly faster).

TODO any 2D first person examples a bit like Ciro's 2D reinforcement learning games?

The examples are present under:but note that that repo is huge, about 4.5 GiB on local disk, as is has tons of assets.

The demos also include a Monaco-editor based sandbox mode where you can edit code directly on the web and see the game update which is a really sweet addition.

No matter how hight the wave intensity, if it the frequency is small, no photons are removed from the material.

This is different from classic waves where energy is proportional to intensity, and coherent with the existence of photons and the Planck-Einstein relation.

Two numbers such that the greatest common divisor is 1.

This is the only way to truly understand and appreciate the subject.

Understanding the experiments gets intimately entangled with basically learning the history of physics, which is extremely beneficial as also highlighted by Ron Maimon, related: there is value in tutorials written by early pioneers of the field.

"How we know" is a basically more fundamental point than "what we know" in the natural sciences.

In the Surely You're Joking, Mr. Feynman chapter O Americano, Outra Vez! Richard Feynman describes his experience teaching in Brazil in the early 1950s, and how everything was memorized, without any explanation of the experiments or that the theory has some relationship to the real world!

Although things have improved considerably since in Brazil, Ciro still feels that some areas of physics are still taught without enough experiments described upfront. Notably, ironically, quantum field theory, which is where Feynman himself worked.

Feynman gave huge importance to understanding and explaining experiments, as can also be seen on Richard Feynman Quantum Electrodynamics Lecture at University of Auckland (1979).

Full set of all possible special relativity symmetries:

In simple and concrete terms. Suppose you observe N particles following different trajectories in Spacetime.

There are two observers traveling at constant speed relative to each other, and so they see different trajectories for those particles:Note that the first two types of transformation are exactly the non-relativistic Galilean transformations.

The Poincare group is the set of all matrices such that such a relationship like this exists between two frames of reference.

This idealization does not seems to be possible at all in the context of Maxwell's equations with pointlike particles.

Positive center is way more popular: gearspace.com/board/electronic-music-instruments-and-electronic-music-production/1222518-center-negative-vs-center-positive-power-supply.html

Ciro Santilli believes it generally hurts more than it helps.

Especially when you can't even mention censored things to criticize them. You have to pretend they never existed. So people will forget about them, and do them again in the future.

And when companies do it just to look good, even though it has absolutely no real impact on the lives of those who are discriminated against.

See: cirosantilli.com/china-dictatorship/censorship-of-politically-incorrect-speech

Static case of Maxwell's law for electricity only.

Is implied by Gauss' law if Maxwell's equations: physics.stackexchange.com/questions/44418/are-the-maxwells-equations-enough-to-derive-the-law-of-coulomb

The "static" part is important: if this law were true for moving charges, we would be able to transmit information instantly at infinite distances. This is basically where the idea of field comes in.

Proportionality factor in the Planck-Einstein relation between light energy and frequency.

And analogously for matter, appears in the de Broglie relations relating momentum and frequency. Also appears in the Schrödinger equation, basically as a consequence/cause of the de Broglie relations most likely.

Intuitively, the Planck constant determines at what length scale do quantum effects start to show up for a given energy scale. It is because the Plank constant is very small that we don't perceive quantum effects on everyday energy/length/time scales. On the ${\lim }_{h\to 0}$, quantum mechanics disappears entirely.

A very direct way of thinking about it is to think about what would happen in a double-slit experiment. TODO think more clearly what happens there.

Defined exactly in the 2019 redefinition of the SI base units to:

Compared to Waring's problem, this is potentially much harder, as we can go infinitely negative in our attempts, there isn't a bound on how many tries we can have for each number.

In other words, it is unlikely to have a Conjecture reduction to a halting problem.