- Physics from Symmetry by Jakob Schwichtenberg (2015) page 72
- physics.stackexchange.com/questions/172385/what-is-a-spinor
- physics.stackexchange.com/questions/41211/what-is-the-difference-between-a-spinor-and-a-vector-or-a-tensor
- physics.stackexchange.com/questions/74682/introduction-to-spinors-in-physics-and-their-relation-to-representations
- www.weylmann.com/spinor.pdf
An Introduction to Tensors and Group Theory for Physicists by Nadir Jeevanjee (2011) by 
Ciro Santilli 40 Updated 2025-07-16
Ciro Santilli 40 Updated 2025-07-16This does not seem to go deep into the Standard Model as Physics from Symmetry by Jakob Schwichtenberg (2015), appears to focus more on more basic applications.
But because it is more basic, it does explain some things quite well.
I wonder where the spray painted sign went: twitter.com/profgalloway/status/1229952158667288576/photo/1. As mentioned at officechai.com/startups/amazon-first-office/ and elsewhere, Jeff did all he could to save money, e.g. he made the desks himself from pieces of wood. Mentioned e.g. at youtu.be/J2xGBlT0cqY?t=345 from Video 4. "Jeff Bezos presentation at MIT (2002)".
Jeff Bezos interview by Chuck Films (1997)
Source. On the street, with a lot of car noise. CC BY-SA, nice.Order from Bulgaria by Jeff Bezos (2002)
Source. Full video: Video 4. "Jeff Bezos presentation at MIT (2002)"- youtu.be/J2xGBlT0cqY?t=220 why Seattle: tech talent, and nearest to the largest book warehouse in Roseburg Oregon
- youtu.be/J2xGBlT0cqY?t=232 first hire, VP of Engineering, Shel Kaphan
- youtu.be/J2xGBlT0cqY?t=267 screenshot of the first version. Can't find any working version from before 2000 on web.archive.org/web/19990601000000*/amazon.com unfortunately.
- youtu.be/J2xGBlT0cqY?t=303 kadabra/cadaver
- youtu.be/J2xGBlT0cqY?t=345 Shel, how tall do you want your desk to be?
- youtu.be/J2xGBlT0cqY?t=610 order from Bulgaria: Video 3. "Order from Bulgaria by Jeff Bezos (2002)"
- youtu.be/J2xGBlT0cqY?t=733 customers don't really know what they want. One is reminded of Steve Jobs customers don't know what they want quote
- youtu.be/J2xGBlT0cqY?t=1010 item merging in a single package from warehouse
- youtu.be/J2xGBlT0cqY?t=1187 and other points mentions repeatedly how much effort they've put into result personalization. But of course, that also means tracking everything people do. Including users that are not logged in. Would not fly well in 2020's increasing privacy concerns!
- youtu.be/J2xGBlT0cqY?t=1251 A/B testing
- youtu.be/J2xGBlT0cqY?t=1314 passes word to employee Robert Frederick, MIT alumni, black dude, AWS manager
- youtu.be/J2xGBlT0cqY?t=1517 demos something in AWS
- youtu.be/J2xGBlT0cqY?t=2171 Jeff's back
- youtu.be/J2xGBlT0cqY?t=2312 similarity searches on some somewhat perverted for-male books. Golden. 2020's political correctness would never allow that in a presentation. A bit further ahead mentions they've optimized to run it in "small machines" with only 2GB RAM, still likely large for the time. Also mentions that if you do it naively, then you're going to say "also bought Harry Potter" for everyone (hugely popular book at the time). You've got to work harder to do better non obvious recommendations.
- youtu.be/J2xGBlT0cqY?t=2409 warehouse uses a technique called random stow, which store items randomly.
- youtu.be/J2xGBlT0cqY?t=2563 OXO Good Grips Salad Spinner. The reviews must be fake, but Jeff doesn't recognize it. Priceless. Still on sale: www.amazon.co.uk/OXO-Good-Grips-Salad-Spinner/dp/B009KCFHAW
- youtu.be/J2xGBlT0cqY?t=2599 decentralized pub/sub pattern, cache warming
- youtu.be/J2xGBlT0cqY?t=2685 "you've bought this previously feature" that reduces sales: people forget they bought things and buy them a second time!
- youtu.be/J2xGBlT0cqY?t=2938 vote fraud after someone from crowd mentions. God reviewed the Bible.
- youtu.be/J2xGBlT0cqY?t=3253 hiring slide with contact jeff@amazon.com Send your CV, today!
Jeff Bezos Revealed by Bloomberg (2015)
Source. cosine by Jeff Bezos (2018)
Source. Yasantha Rajakarunanayake: twitter.com/yasantha62/status/1042052665893511168.
Bibliography:
- archive.ph/ucSHN This is what it was like to work at Amazon 20 years ago (2015). Good annecdotes from the first offices.
Does the exact position of vertices matter in Feynman diagrams? by Ciro Santilli 40 Updated 2025-07-16
Ciro Santilli 40 Updated 2025-07-16Ciro Santilli once visited the chemistry department of a world leading university, and the chemists there were obsessed with NMR. They had small benchtop NMR machines. They had larger machines. They had a room full of huge machines. They had them in corridors and on desk tops. Chemists really love that stuff. More precisely, these are used for NMR spectroscopy, which helps identify what a sample is made of.
Introduction to NMR by Allery Chemistry
. Source. - only works with an odd number of nucleons
- apply strong magnetic field, this separates the energy of up and down spins. Most spins align with field.
- send radio waves into sample to make nucleons go to upper energy level. We can see that the energy difference is small since we are talking about radio waves, low frequency.
- when nucleon goes back down, it re-emits radio waves, and we detect that. TODO: how do we not get that confused with the input wave, which is presumably at the same frequency? It appears to send pulses, and then wait for the response.
How to Prepare and Run a NMR Sample by University of Bath (2017)
Source. This is a more direct howto, cool to see. Uses a Bruker Corporation 300. They have a robotic arm add-on. Shows spectrum on computer screen at the end. Shame no molecule identification after that!This video has the merit of showing real equipment usage, including sample preparation.
Says clearly that NMR is the most important way to identify organic compounds.
- youtu.be/uNM801B9Y84?t=41 lists some of the most common targets, including hydrogen and carbon-13
- youtu.be/uNM801B9Y84?t=124 ethanol example
- youtu.be/uNM801B9Y84?t=251 they use solvents where all protium is replaced by deuterium to not affect results. Genius.
- youtu.be/uNM801B9Y84?t=354 usually they do 16 radio wave pulses
NMR spectroscopy visualized by ScienceSketch
. Source. 2020. Decent explanation with animation. Could go into a bit more numbers, but OK.Or in other words, it is basically implementing an operating system/firmware yourself ad hoc, together with your actual program.
Ubuntu 24.04 "The application files has closed unexpectedly" by Ciro Santilli 40 Updated 2025-07-16
Ciro Santilli 40 Updated 2025-07-16Happens at startup without doing anything, and then keeps happening randomly infinitely many times... on a almost clean 24.04 ISO install on Dell Inspiron 15 3520... God how can it be so bad.
Viewing the apport issue a bit further shows title:
nautilus crashed with sigabrt in g_assertion_message_exprPossibly related:
- www.reddit.com/r/Ubuntu/comments/1ce1027/2404_is_a_terrible_release/
- bugs.launchpad.net/ubuntu/+source/nautilus/+bug/1795210
- bugs.launchpad.net/ubuntu/+source/nautilus/+bug/1823529
- askubuntu.com/questions/1406294/nautilus-keeps-crashing-in-22-04
- superuser.com/questions/42068/application-are-closed-down-unexpectedly-under-ubuntu
- ubuntuforums.org/showthread.php?t=2466502
- x.com/cirosantilli/status/1792792620323967227
The solution on kernel 6.2 was:as per comments under: bugs.launchpad.net/ubuntu/+source/linux/+bug/2012559. This also made the nvidia driver work: Find GPU information in Ubuntu.
sudo apt instal nvidia-driver-515Previously I had:and it blew up before reaching disk decryption.
nvidia-driver-510I also tried:but that broke in a different way:
nvidia-driver-525Finished apport-autoreport.service - Process error reports when automatic reporting is enabled.
nvidia-modeset: ERROR: GPU:0: Idling display engine timed out: 0x0000947d:0:0:407
(1 of 2) Job systemd-backlight@backlight: nvidia_e.service/start running (32s no limit) Pinned article: Introduction to the OurBigBook Project
Welcome to the OurBigBook Project! Our goal is to create the perfect publishing platform for STEM subjects, and get university-level students to write the best free STEM tutorials ever.
Everyone is welcome to create an account and play with the site: ourbigbook.com/go/register. We belive that students themselves can write amazing tutorials, but teachers are welcome too. You can write about anything you want, it doesn't have to be STEM or even educational. Silly test content is very welcome and you won't be penalized in any way. Just keep it legal!
Intro to OurBigBook
. Source. We have two killer features:
- topics: topics group articles by different users with the same title, e.g. here is the topic for the "Fundamental Theorem of Calculus" ourbigbook.com/go/topic/fundamental-theorem-of-calculusArticles of different users are sorted by upvote within each article page. This feature is a bit like:
- a Wikipedia where each user can have their own version of each article
- a Q&A website like Stack Overflow, where multiple people can give their views on a given topic, and the best ones are sorted by upvote. Except you don't need to wait for someone to ask first, and any topic goes, no matter how narrow or broad
This feature makes it possible for readers to find better explanations of any topic created by other writers. And it allows writers to create an explanation in a place that readers might actually find it.
Figure 1. Screenshot of the "Derivative" topic page. View it live at: ourbigbook.com/go/topic/derivativeVideo 2. OurBigBook Web topics demo. Source. - local editing: you can store all your personal knowledge base content locally in a plaintext markup format that can be edited locally and published either:This way you can be sure that even if OurBigBook.com were to go down one day (which we have no plans to do as it is quite cheap to host!), your content will still be perfectly readable as a static site.
- to OurBigBook.com to get awesome multi-user features like topics and likes
- as HTML files to a static website, which you can host yourself for free on many external providers like GitHub Pages, and remain in full control
Figure 3. Visual Studio Code extension installation.
Figure 4. Visual Studio Code extension tree navigation.
Figure 5. Web editor. You can also edit articles on the Web editor without installing anything locally.Video 3. Edit locally and publish demo. Source. This shows editing OurBigBook Markup and publishing it using the Visual Studio Code extension.Video 4. OurBigBook Visual Studio Code extension editing and navigation demo. Source. 
- Infinitely deep tables of contents:
All our software is open source and hosted at: github.com/ourbigbook/ourbigbook
Further documentation can be found at: docs.ourbigbook.com
Feel free to reach our to us for any help or suggestions: docs.ourbigbook.com/#contact