Like the rest of the Standard Model Lagrangian, this can be split into two parts:
- spacetime symmetry: reaches the derivation of the Dirac equation, but has no interactions
- add the internal symmetry to add interactions, which reaches the full equation
Deriving the qED Lagrangian by Dietterich Labs (2018)
Source. As mentioned at the start of the video, he starts with the Dirac equation Lagrangian derived in a previous video. It has nothing to do with electromagnetism specifically.
He notes that that Dirac Lagrangian, besides being globally Lorentz invariant, it also also has a global invariance.
However, it does not have a local invariance if the transformation depends on the point in spacetime.
He doesn't mention it, but I think this is highly desirable, because in general local symmetries of the Lagrangian imply conserved currents, and in this case we want conservation of charges.
To fix that, he adds an extra gauge field (a field of matrices) to the regular derivative, and the resulting derivative has a fancy name: the covariant derivative.
Then finally he notes that this gauge field he had to add has to transform exactly like the electromagnetic four-potential!
So he uses that as the gauge, and also adds in the Maxwell Lagrangian in the same go. It is kind of a guess, but it is a natural guess, and it turns out to be correct.
Skullcandy earphones, first one circa. 2016 most likely. Used them a lot, these are good.
2023-07: one of the sides broke near center, rebuying.
2021-07: wire half broke near connector, only works in some positions. The funny thing is: only voices seem to be blocked out! Rebuying.
2021-06: a small bottom piece of the left earpiece broke. Wire seems find, that is like a little extension to protect wire. Let's see for how long.
2020-20: wires at one of ears broke, not sure how.
Look they looked exactly like: "Skullcandy Smokin' Buds 2 In-Ear Audio Earbud Headphones with In-Line Microphone - Black".
Re-buying that one 10 pounds:
Tech specs:
Weight: 4gConnection Type: 3.5mm AUX CableImpedence: 32 ohmsDriver Diameter: 9mmTHD: <0.1% (1mW/500Hz) (0.0234)Sound Pressure Level: 95 dB (1mW/500Hz)Frequency Response: 20kHz - 20HzHeadphone Type: In-Ear
PCIe TLC OPAL2.
www.samsung.com/semiconductor/global.semi/file/resource/2018/05/PM981_M.2_SSD_Datasheet_v1.3_for_General.pdf | web.archive.org/web/20181224225410/https://www.samsung.com/semiconductor/global.semi/file/resource/2018/05/PM981_M.2_SSD_Datasheet_v1.3_for_General.pdf
sudo hdparm -Tt /dev/nvme0n1p5 on Ubuntu 20.04: Timing cached reads: 29812 MB in 1.99 seconds = 15007.00 MB/sec
HDIO_DRIVE_CMD(identify) failed: Inappropriate ioctl for device
Timing buffered disk reads: 6328 MB in 3.00 seconds = 2109.00 MB/secNominal maximum sequential read speed: 3,000 MB/s
Integer factorization algorithms better than Shor's algorithm Updated 2024-12-23 +Created 1970-01-01
- 2023 www.schneier.com/blog/archives/2023/01/breaking-rsa-with-a-quantum-computer.html comments on "Factoring integers with sublinear resources on a superconducting quantum processor” arxiv.org/pdf/2212.12372.pdf
A group of Chinese researchers have just published a paper claiming that they can—although they have not yet done so—break 2048-bit RSA. This is something to take seriously. It might not be correct, but it’s not obviously wrong.We have long known from Shor’s algorithm that factoring with a quantum computer is easy. But it takes a big quantum computer, on the orders of millions of qbits, to factor anything resembling the key sizes we use today. What the researchers have done is combine classical lattice reduction factoring techniques with a quantum approximate optimization algorithm. This means that they only need a quantum computer with 372 qbits, which is well within what’s possible today. (The IBM Osprey is a 433-qbit quantum computer, for example. Others are on their way as well.)
Ciro Santilli believes that there is a positive correlation between being a software engineer and liking Buddhist-like things.
Maybe it is linked to minimalism and DRY, which software engineers value so greatly.
Even Ciro had to try an unoriginal Buddhist joke intro in one of this Stack Overflow answers.
Ciro also feels that his "minimal reproducible example" scientific language/concept learning method obsession of breaking things into tiny sub-problems has a strong link with Koans.
Some notable Buddhism/programmer examples:
- www.catb.org/~esr/writings/unix-koans/ "The Unix Koans of Master Foo - Rootless Root (无根的根)" by the legendary Eric Steven Raymond is notable
- thecodelesscode.com/ "The Codeless Code" by anonymous Qi.
- canonical.org/~kragen/tao-of-programming.html
- wiki.c2.com/?MysticalProgrammingKoans
- rubykoans.com/ even evil programming languages adopt them!
- The Zen of Python
Another thing that points the correlation out is the existence of wattsalan.github.io/ on a
github.io about Alan Watts.- www.youtube.com/watch?v=1Z9wo2CzJO8 "Schrodinger equation solved numerically in 3D" by Tetsuya Matsuno. 3D hydrogen atom, code may be hidden in some paper, maybe
- www.youtube.com/playlist?list=PLdCdV2GBGyXM0j66zrpDy2aMXr6cgrBJA "Computational Quantum Mechanics" by Let's Code Physics. Uses a 1D trinket.io.
- www.youtube.com/watch?v=BBt8EugN03Q Simulating Quantum Systems [Split Operator Method] by LeiosOS (2018)
- www.youtube.com/watch?v=86x0_-JGlGQ Simulating the Quantum World on a Classical Computer by Garnet Chan (2016) discusses how modeling only local entanglement can make certain simulations feasible
Simulation of the time-dependent Schrodinger equation (JavaScript Animation) by Coding Physics (2019)
Source. Source code: github.com/CodingPhysics/Schroedinger. One dimensional potentials, non-interacting particles. The code is clean, graphics based on github.com/processing/p5.js, and all maths from scratch. Source organization and comments are typical of numerical code, the anonymous author is was likely a Fortran user in the past.
A potential change patch in
sketch.js:- potential: x => 2E+4*Math.pow((4*x - 1)*(4*x - 3),2),
+ potential: x => 4*Math.pow(x - 0.5, 2),Quantum Mechanics 5b - Schrödinger Equation II by ViaScience (2013)
Source. 2D non-interacting particle in a box, description says using Scilab and points to source. Has a double slit simulation.Visualization of Quantum Physics (Quantum Mechanics) by udiprod (2017)
Source. Closed source, but a fantastic visualization and explanation of a 1D free wave packet, including how measurement snaps position to the measured range, position and momentum space and the uncertainty principle.We select for the general Equation "Schrodinger equation":giving the full explicit partial differential equation:
- , the linear cartesian coordinate in the x direction
- , which analogous to the sum of kinetic and potential energy in classical mechanics
Equation 1.
Schrödinger equation for a one dimensional particle
. The corresponding time-independent Schrödinger equation for this equation is:
Equation 2.
time-independent Schrödinger equation for a one dimensional particle
. - English: Cambridge CPE grade B in 2004. Proficient, with minor defects in collocation/pronunciation. Learned from formal courses and from living in the UK for a few months when he was 10.
- French: TCF grade C2 in 2011. Proficient, with a bit more defects than English. Studied and lived in France.
- Brazilian Portuguese: Native speaker
- Chinese: see github.com/cirosantilli/china-dictatorship/tree/df0852b22e585785d734ec69719eddf63f9676a5#do-you-speak-chinese
When asked, Ciro likes to say that he speaks something between 1.5 and 3.5 languages in total, depending on how you count, because Portuguese, French and English are 99.99% the same, and Chinese is completely different but Ciro only knows about 50% of it if counted optimistically.
- web.archive.org/web/20150623011722/http://users.physik.fu-berlin.de/~kleinert/b6/psfiles/qft.pdf by Hagen Kleinert (2015). 1500 pages!
- The Quantum Theory of Fields by Steven Weinberg (2013) www.cambridge.org/core/books/quantum-theory-of-fields/22986119910BF6A2EFE42684801A3BDF
- Quantum Field Theory by Lewis H. Ryder 2nd edition (1996) www.amazon.co.uk/Quantum-Field-Theory-Lewis-Ryder/dp/0521478146
- Lectures of Quantum Field Theory by Ashok Das (2018) www.amazon.co.uk/Lectures-Quantum-Field-Theory-Ashok-ebook/dp/B07CL8Y3KY
- A Modern Introduction to Quantum Field Theory by Michele Maggiore (2005) www.amazon.co.uk/Modern-Introduction-Quantum-Theory-Physics/dp/0198520743
I like relativistic quantum mechanics.
Best mathematical explanation: Section "Spin comes naturally when adding relativity to quantum mechanics".
Physics from Symmetry by Jakob Schwichtenberg (2015) chapter 3.9 "Elementary particles" has an amazing summary of the preceding chapters the spin value has a relation to the representations of the Lorentz group, which encodes the spacetime symmetry that each particle observes. These symmetries can be characterized by small integer numbers:
- spin 0: representation
- spin half: representation
- spin 1: representationAs usual, we don't know why there aren't elementary particles with other spins, as we could construct them.
TODO clear attribution source:
Some people say, "Give the customers what they want." But that's not my approach. Our job is to figure out what they're going to want before they do. I think Henry Ford once said, "If I'd asked customers what they wanted, they would have told me, 'A faster horse!'" People don't know what they want until you show it to them. That's why I never rely on market research. Our task is to read things that are not yet on the page.
Quantum field theory in a nutshell by Anthony Zee (2010) Updated 2024-12-23 +Created 1970-01-01
ISBN-13: 978-0691140346
lecture 1 mentions that this book is quick and dirty, as one might guess from the title. Ciro Santilli thinks he's gonna like this one.
First edition: from 2003, www.amazon.com/dp/0691010196, ISBN-13: 978-0691010199.
Summary:
Quantum numbers appear directly in the Schrödinger equation solution for the hydrogen atom.
However, it very cool that they are actually discovered before the Schrödinger equation, and are present in the Bohr model (principal quantum number) and the Bohr-Sommerfeld model (azimuthal quantum number and magnetic quantum number) of the atom. This must be because they observed direct effects of those numbers in some experiments. TODO which experiments.
E.g. The Quantum Story by Jim Baggott (2011) page 34 mentions:This refers to forbidden mechanism. TODO concrete example, ideally the first one to be noticed. How can you notice this if the energy depends only on the principal quantum number?
As the various lines in the spectrum were identified with different quantum jumps between different orbits, it was soon discovered that not all the possible jumps were appearing. Some lines were missing. For some reason certain jumps were forbidden. An elaborate scheme of ‘selection rules’ was established by Bohr and Sommerfeld to account for those jumps that were allowed and those that were forbidden.
Quantum Numbers, Atomic Orbitals, and Electron configurations by Professor Dave Explains (2015)
Source. He does not say the key words "Eigenvalues of the Schrödinger equation" (Which solve it), but the summary of results is good enough.Patches which were merged by Ciro himself on repositories which eh feels have large public visibility, e.g. those to which he has been given push permission.
Repositories to which Ciro gained push permission because of his contributions:
The fact that ATP is the universal energy storage mollecule of all life on Earth is such an incredible unifying principle of biology!
It is the direct output of all the major forms of "energy generation" in cells: ATP synthesis mechanism.
It is just as fundamental as the genetic code for example.
No wonder dozens of Nobel Prizes were related to its discovery, given its complexity.
Article likely written by him: www.theguardian.com/commentisfree/2010/feb/22/home-schooling-register-families
“Especially my father. He was doing most of it and he is a savoury, strong character. He has strong beliefs about the world and in himself, and he was helping me a lot, even when I was at university as an undergraduate.”An only child, Arran was born in 1995 in Glasgow, where his parents were studying at the time. His father has Spanish lineage, having a great grandfather who was a sailor who moved from Spain to St Vincent in the Carribean. A son later left the islands for the UK where he married an English woman. Arran’s mother is Norwegian.“My father was writing and my mother is an economist. They both worked from home which also made things easier,” Arran says.
One of the articles says his father has a PhD. TODO where did he work? What's his PhD on? Photo: www.topfoto.co.uk/asset/1357880/
www.thetimes.co.uk/article/the-everyday-genius-pxsq5c50kt9:
Neil, a political economist, attended state and private schools in Hampshire but was also taught for a period at home by his mother.
It’s strange because for most people maths is a real turn-off, yet maths is all about patterns and children of two or three love patterns. It just shows that schools are doing something seriously wrong.”
As a Brazilian, Ciro Santilli used to really love playing soccer (but not watching it), until he hurt his knee.
Playing soccer just feels amazing, because you are constantly running around, but with a more specific goal in mind: to get that ball into that goal!
Playing soccer was specially amazing in the flat wet sand beach of Santos. weekend, the sea, feet touching the sand, the sun going down, and your school mates next to you. Nirvana.
It is also true that under those conditions, the skin of your feet will get ripped off due to running on the slightly wet and flat sand no matter how thick it has become. But it is worth it.
Teams would often be slit between "the team with shirts vs the team without shirts", who would just take off their shirts. The two best players would take turns picking players into their teams, the first one to pick would be decided by odds and evens (par ou ímpar).
A pair of Havaianas, or Havaianas rip-offs, stuck into the sand, or even just some school bags, would do as a goal posts. More organized people, especially adults, would have their own water pipe goal with a proper net and all. But doing so would spoil the fun of endless discussions if a non flat ball had gone in or not into an imaginary rectangle.
That's how soccer was meant to be played.
Ciro became however disillusioned with soccer after his injury. It is a shame.
And so after that, Ciro decided to dedicate himself to sports where you can't hurt your knee.
Ciro hates water, so swimming is out of the question. What could be more boring than going back and forth on a fixed location a million times to gain some milliseconds?
And so Ciro has been left with the gym as the only main option for a while.
Running would have been a consideration, but Ciro Santilli's legs sometimes itch when he runs.
This is until he ended up living in a place with decent roads for cycling in the late 2010's, which led to Ciro Santilli's cycling.
Adults playing soccer in Santos, São Paulo, Brazil beach on a rainy day
. Source. It is still warm though as you can see from their clothing.
Ciro Santilli with his soon-to-be Ciro Santilli's mother-in-law during his wedding in 2017
. www.maketecheasier.com/use-stockfish-cli-master-chess is a good source.
Most of what follows is part of the Universal Chess Interface. Tested on Ubuntu 22.10, Stockfish 14.1.
After starting Sweet ASCII art. where:
stockfish on the command line, d (presumably display) contains: +---+---+---+---+---+---+---+---+
| r | n | b | q | k | b | n | r | 8
+---+---+---+---+---+---+---+---+
| p | p | p | p | p | p | p | p | 7
+---+---+---+---+---+---+---+---+
| | | | | | | | | 6
+---+---+---+---+---+---+---+---+
| | | | | | | | | 5
+---+---+---+---+---+---+---+---+
| | | | | | | | | 4
+---+---+---+---+---+---+---+---+
| | | | | | | | | 3
+---+---+---+---+---+---+---+---+
| P | P | P | P | P | P | P | P | 2
+---+---+---+---+---+---+---+---+
| R | N | B | Q | K | B | N | R | 1
+---+---+---+---+---+---+---+---+
a b c d e f g h
Fen: rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1
Key: 8F8F01D4562F59FBFen: FEN notationKey: TODO
Move white king's pawn from e2 to e4:Then display again:gives:so we see that the pawn moved.
position startpos moves e2e4d +---+---+---+---+---+---+---+---+
| r | n | b | q | k | b | n | r | 8
+---+---+---+---+---+---+---+---+
| p | p | p | p | p | p | p | p | 7
+---+---+---+---+---+---+---+---+
| | | | | | | | | 6
+---+---+---+---+---+---+---+---+
| | | | | | | | | 5
+---+---+---+---+---+---+---+---+
| | | | | P | | | | 4
+---+---+---+---+---+---+---+---+
| | | | | | | | | 3
+---+---+---+---+---+---+---+---+
| P | P | P | P | | P | P | P | 2
+---+---+---+---+---+---+---+---+
| R | N | B | Q | K | B | N | R | 1
+---+---+---+---+---+---+---+---+
a b c d e f g h
Fen: rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR b KQkq - 0 1
Key: B46022469E3DD31BNow let's make Stockfish think for one second what is the next best move for black:gives as the last line:TODO:
go movetime 1000bestmove c7c5 ponder g1f3- what is ponder? Something to do with thinking on the opponent's turn: permanent brain.
- understand the previous lines
To make the move it as suggested for black, we have to either repeat the entire sequence of movements:or alternatively we could also use the previous FEN notation as a starting point;Note how the Universal Chess Interface interface is very simple: we just load a state and then decide what to do next for that one state. The engine holds only one and exactly one state at a time, and you can't even modify it differentially without loading new one from scratch.
position startpos moves e2e4 c7c5d: +---+---+---+---+---+---+---+---+
| r | n | b | q | k | b | n | r | 8
+---+---+---+---+---+---+---+---+
| p | p | | p | p | p | p | p | 7
+---+---+---+---+---+---+---+---+
| | | | | | | | | 6
+---+---+---+---+---+---+---+---+
| | | p | | | | | | 5
+---+---+---+---+---+---+---+---+
| | | | | P | | | | 4
+---+---+---+---+---+---+---+---+
| | | | | | | | | 3
+---+---+---+---+---+---+---+---+
| P | P | P | P | | P | P | P | 2
+---+---+---+---+---+---+---+---+
| R | N | B | Q | K | B | N | R | 1
+---+---+---+---+---+---+---+---+
a b c d e f g h
Fen: rnbqkbnr/pp1ppppp/8/2p5/4P3/8/PPPP1PPP/RNBQKBNR w KQkq - 0 2
Key: 4CA78BCE9C2980B0position fen rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR b KQkq - 0 1 moves c7c5Let's move white again with our brain with either:
position startpos moves e2e4 c7c5 d2d3
position fen rnbqkbnr/pp1ppppp/8/2p5/4P3/8/PPPP1PPP/RNBQKBNR w KQkq - 0 2 moves d2d3Set a specific position from
fen:position fen rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR b KQkq - 0 1 Unlisted articles are being shown, click here to show only listed articles.