Expansion of the universe by Ciro Santilli 35 Updated +Created
Europe by Ciro Santilli 35 Updated +Created
For the most part, a great pseudo-country to live in with lots of cultural diversity, art and safety.
However, Europe is in economic decline after all its Jewish and German geniuses fled in/after World War II and due to having more than one natural language is bad for the world.
Essential amino acid by Ciro Santilli 35 Updated +Created
Erhu by Ciro Santilli 35 Updated +Created
Figure 1.
A blind erhu street performer playing in Jingzhou, Hubei (2006)
Source. Playing the erhu is a traditional occupation for blind people in China, a notable example being Abing.
Video 2.
The 12 Most Famous Erhu Melodies in China (2021)
Source. TODO transcribe list.
Erdős' conjecture on powers of 2 by Ciro Santilli 35 Updated +Created
Described at: arxiv.org/pdf/2107.12475.pdf where a relation to the Busy beaver scale is proven, and the intuitive relation to the Collatz conjecture described. Perhaps more directly: demonstrations.wolfram.com/CollatzSequenceComputedByATuringMachine/
Enrico Fermi by Ciro Santilli 35 Updated +Created
Died of cancer at age 53. Ciro Santilli just can't help but speculate that it is linked to radioactivity exposure.
Energy-momentum relation by Ciro Santilli 35 Updated +Created
Emulator by Ciro Santilli 35 Updated +Created
One of the things Ciro Santilli really likes, see: Linux Kernel Module Cheat.
Elliptic curve primality by Ciro Santilli 35 Updated +Created
Polynomial time for most inputs, but not for some very rare ones. TODO can they be determined?
But it is better in practice than the AKS primality test, which is always polynomial time.
AC Josephson effect by Ciro Santilli 35 Updated +Created
This is what happens when you apply a DC voltage across a Josephson junction.
It is called "AC effect" because when we apply a DC voltage, it produces an alternating current on the device.
By looking at the Josephson equations, we see that a positive constant, then just increases linearly without bound.
Therefore, from the first equation:
we see that the current will just vary sinusoidally between .
This meas that we can use a Josephson junction as a perfect voltage to frequency converter.
Wikipedia mentions that this frequency is , so it is very very high, so we are not able to view individual points of the sine curve separately with our instruments.
Also it is likely not going to be very useful for many practical applications in this mode.
Figure 1. . Source.
Voltage is horizontal, current vertical. The vertical bar in the middle is the effect of interest: the current is going up and down very quickly between , the Josephson current of the device. Because it is too quick for the oscilloscope, we just see a solid vertical bar.
The non vertical curves at right and left are just other effects we are not interested in.
TODO what does it mean that there is no line at all near the central vertical line? What happens at those voltages?
Video 1.
Superconducting Transition of Josephson junction by Christina Wicker (2016)
Source. Amazing video that presumably shows the screen of a digital oscilloscope doing a voltage sweep as temperature is reduced and superconductivity is reached.
Figure 2. . So it appears that there is a zero current between and . Why doesn't it show up on the oscilloscope sweeps, e.g. Video 1. "Superconducting Transition of Josephson junction by Christina Wicker (2016)"?
Elliptic curve cryptography by Ciro Santilli 35 Updated +Created
Eligius pool by Ciro Santilli 35 Updated +Created
Created by Luke Dashjr.
The pool is named after Saint Eligius, patron of miners[ref]
Eligius also means to "choose" or "chosen" in Latin: en.wiktionary.org/wiki/Eligius, same root as "to elect" in modern English presumably.
STT_NOTYPE by Ciro Santilli 35 Updated +Created
Then come the most important symbols:
Num:    Value          Size Type    Bind   Vis      Ndx Name
  4: 0000000000000000     0 NOTYPE  LOCAL  DEFAULT    1 hello_world
  5: 000000000000000d     0 NOTYPE  LOCAL  DEFAULT  ABS hello_world_len
  6: 0000000000000000     0 NOTYPE  GLOBAL DEFAULT    2 _start
hello_world string is in the .data section (index 1). It's value is 0: it points to the first byte of that section.
_start is marked with GLOBAL visibility since we wrote:
global _start
in NASM. This is necessary since it must be seen as the entry point. Unlike in C, by default NASM labels are local.
.rel.text by Ciro Santilli 35 Updated +Created
Besides sh_type == SHT_RELA, there also exists SHT_REL, which would have section name .text.rel (not present in this object file).
Those represent the same struct, but without the addend, e.g.:
typedef struct {
    Elf64_Addr  r_offset;
    Elf64_Xword r_info;
} Elf64_Rela;
The ELF standard says that in many cases the both can be used, and it is just a matter of convenience.

Pinned article: ourbigbook/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!
We have two killer features:
  1. 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-calculus
    Articles 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/derivative
  2. 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.
    Figure 5. . 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.
  3. https://raw.githubusercontent.com/ourbigbook/ourbigbook-media/master/feature/x/hilbert-space-arrow.png
  4. Infinitely deep tables of contents:
    Figure 6.
    Dynamic article tree with infinitely deep table of contents
    .
    Descendant pages can also show up as toplevel e.g.: ourbigbook.com/cirosantilli/chordate-subclade
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