Entry 1 has ELF64_R_TYPE == STT_FILE. ELF64_R_TYPE is continued inside of st_info.
  • 10 8: st_name = 01000000 = character 1 in the .strtab, which until the following \0 makes hello_world.asm
    This piece of information file may be used by the linker to decide on which segment sections go: e.g. in ld linker script we write:
    segment_name :
    {
        file(section)
    }
    to pick a section from a given file.
    Most of the time however, we will just dump all sections with a given name together with:
    segment_name :
    {
        *(section)
    }
  • 10 12: st_info = 04
    Bits 0-3 = ELF64_R_TYPE = Type = 4 = STT_FILE: the main purpose of this entry is to use st_name to indicate the name of the file which generated this object file.
    Bits 4-7 = ELF64_ST_BIND = Binding = 0 = STB_LOCAL. Required value for STT_FILE.
  • 10 13: st_shndx = Symbol Table Section header Index = f1ff = SHN_ABS. Required for STT_FILE.
  • 20 0: st_value = 8x 00: required for value for STT_FILE
  • 20 8: st_size = 8x 00: no allocated size
Now from the readelf, we interpret the others quickly.
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.
This is a good book. It is rather short, very direct, which is a good thing. At some points it is slightly too direct, but to a large extent it gets it right.
The main goal of the book is to basically to build the Standard Model Lagrangian from only initial symmetry considerations, notably the Poincaré group + internal symmetries.
The book doesn't really show how to extract numbers from that Lagrangian, but perhaps that can be pardoned, do one thing and do it well.
Jean Baptiste Perrin by Ciro Santilli 37 Updated 2025-07-16
This seems like a cool dude. Besides a hardcore scientist, he also made many important contributions to the French education and research system.
Ciro had a small accident in 2021. It wasn't ultra serious, a few cuts, but could have been worse. Here's a post mortem.
Ciro was going to cycle 120 km between two locations he had never cycled before. Ciro had cycled this distance before many many times, so he thought he could do it.
What went wrong:
  • on both ends were cities, larger than those Ciro is used to
  • on the start, was a port city. You do not want to cycle in port areas, ever! Lots of trucks, narrow side-walks, bad road, danger danger!
  • on both sides, endless suburbia. This means you have to check your map every 3 seconds to know which little stree to turn, which is very hard without a way to attach your map to your bike. Ciro had his on his pocket. You lose a lot of time like that!
  • there wasn't a lot of sunlight at the time of the year. Not criticial, but still, less than ideal.
  • during the ride, part of the "well documented and safe cycle route" was closed off for repairs. It was unclear what the best alternative would be. Ciro went down a path, but it turned to be horrendous countryside, he had to pull his bike over fences
  • by then, Ciro was tired and a bit late. He had only eaten sweets all day long. They give you calories, but there's always something missing in them.
  • Ciro arrived at the very very large target city, and it was getting dark, and it was rush hour, lots of cars. This was already back on the official bike path, but even those paths are torduous in suburbia
  • also, Ciro was meant to meet his wife later, and he was in a rush, worried that she would be worried about him
  • at one point, Ciro took the wrong turn for a few hundred meters
  • he realized, and turned back
  • when coming back, now extra impatient because o the wrong turn, the place he had come from was actually one way street for a very short while until the right turn, so Ciro went against the correct direction...
  • a car came. It was relatively slow, because the road was slight uphill for the car, and a turn. The slight downhill also meant Ciro was going a bit faster than he realized
  • Ciro tried to go into the sidewalk anyways to make sure he was clear off the car (he was already). When he tried, the wheel stuck, and he flew forward, hitting a wall slightly
This was a perfect example of how many small things add up to an accident.
You have to know when you are tired and hungry and impatient. This is where huge danger lies.
Stop at a shop, eat, sit down. Darkness is not that dangerous if you have lights.
Take a train outside of large cities if needed. Crossing large cities is not something to be taken lightly. You need calm and time to do so safely.
Pascual Jordan by Ciro Santilli 37 Updated 2025-07-16
One of the leading figures of the early development of quantum electrodynamics.

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!
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