Crystal detector Updated 2025-07-16
The first diodes. These were apparently incredibly unreliable, especially for portable radios, as you had to randomly search for the best contact point you could find in a random polycrystalline material!!
And also quality was highly dependant on where the material was sourced from as that affected the impurities present in the material. Later this was understood to be an issue of doping.
It was so unreliable that vacuum tube diodes overtook them in many applications, even though crystal detectors are actually semiconductor diodes, which eventually won over!
For a long time, before artificial semiconductors kicked in, people just didn't know the underlying physical working principle of these detectors. What I cannot create, I do not understand basically.
MuJoCo getting started Updated 2025-07-16
Tested on Ubuntu 23.10;
git clone https://github.com/google-deepmind/mujoco
cd mujoco
git checkout 5d46c39529819d1b31249e249ca399f306a108ac
mkdir -p build
cd build
cmake ..
make -jNow let's play. Minimal interactive UI simulation of a simple MJCF scene with one falling cube:Test soure code: github.com/google-deepmind/mujoco/blob/5d46c39529819d1b31249e249ca399f306a108ac/sample/basic.cc. The only thing you can do is rotate the scene with the computer mouse it seems. Mentioned at: mujoco.readthedocs.io/en/2.2.2/programming.html#sabasic
bin/basic ../doc/_static/hello.xmlSome more interesting models can be found under the
model/ directory: github.com/google-deepmind/mujoco/tree/5d46c39529819d1b31249e249ca399f306a108ac/model E.g. the imaginary humanoid robot DeepMind used in many demos can be seen with:bin/basic ../model/humanoid/humanoid.xmlA more advanced UI with a few controls:Test soure code: github.com/google-deepmind/mujoco/tree/5d46c39529819d1b31249e249ca399f306a108ac/simulate. Mentioned at: mujoco.readthedocs.io/en/2.2.2/programming.html#sasimulate
bin/simulate ../doc/_static/hello.xmlA very cool thing about that UI is that you can manually control joints. There are no joints in the hello.xml, but e.g. with the humanoid model:under "Control" you move each joint of the robot separately which is quite cool.
bin/simulate ../model/humanoid/humanoid.xmlThere's also a Mentioned at: mujoco.readthedocs.io/en/2.2.2/programming.html#sarecord but TODO that produced a broken video, related issues:
bin/record test executable that presumably renders the simulation directly to a file:bin/record ../doc/_static/hello.xml 5 60 rgb.out
ffmpeg -f rawvideo -pixel_format rgb24 -video_size 800x800 -framerate 60 -i rgb.out -vf "vflip" video.mp4 CUDA hello world Updated 2025-07-16
Daisy chain Bitcoin inscription Updated 2025-07-16
This is a term invented by Ciro Santilli, and refers to a loose set of uncommon Bitcoin inscription methods that involve inscribing one or a small number of payloads per Bitcoin transaction.
These methods are both inefficient and hard to detect and decode, partly because Bitcoin Core does not index spending transactions: bitcoin.stackexchange.com/questions/61794/bitcoin-rpc-how-to-find-the-transaction-that-spends-a-txo. This makes finding them all that more rewarding however.
On the other hand, they do have the advantage of not depending on any block size limits, as their individual transactions are very small.
Dan Abramson Updated 2025-07-16
Dan, if you ever Google yourself here, please contact Ciro Santilli: Section "How to contact Ciro Santilli" to do something with OurBigBook.com. Cheers.
DigitalDreamDoor Updated 2025-07-16
Domain name speculation Updated 2025-07-16
Next.js example Updated 2025-07-16
Our examples are located under nodejs/next:
- nodejs/next/hello-world: a hello world. There's an in-tree one at: github.com/vercel/next.js/tree/e75361fd03872b097e817634c049b3185f24cf56/examples/hello-world, but ours is truly minimal
- nodejs/next/hoc: shows how to use a higher order component (HOC) to factor out
getStaticPropsacross two pages: nodejs/next/hoc/pages/index.js and nodejs/next/hoc/pages/notindex.js - nodejs/next/typescript: simple TypeScript example, minimized from: github.com/vercel/next.js/tree/d61b0761efae09bd9cb1201ff134ed8950d9deca/examples/with-typescriptNotably, that shows how
requireerrors are avoided in that case as mentioned at: stackoverflow.com/questions/64926174/module-not-found-cant-resolve-fs-in-next-js-application/70363153#70363153 - nodejs/next/localStorage: a counter that is persistent across page reloads by using
localStorage. Used in: stackoverflow.com/questions/54819721/next-js-access-localstorage-before-rendering-page/68136224#68136224
Solved ones:
EMBII Updated 2025-07-16
One of the dudes from the AtomSea & EMBII Bitcoin-based file upload system.
- github.com/embiimob
- Real name: likely "Eric Bobby" according to:According to Figure "
Loraine.jpg" however, his mother's name was "Loraine Elizabeth White", so there's some chance his real family name is Mr. White.However according to bitfossil.org/937f70bf641ccabaf623772367df64bd867ad44c53fd227d01f2662e74aeacbf/ his daughter is Maddy Bobby, so maybe he is actually Bobby. - twitter.com/EMBII4U
- twitter.com/TheAtomSea/status/990318090738196481 sample link
- x.com/EMBII4U/status/1901769408453718146 possibly retired in 2021 after working as a barista
- he seems to have been quite interested in natural science at around high school before he decided to waste his life as a crypto artist
- x.com/EMBII4U/status/1936278732760666236:
I was science student of the year 1992 all because of molecular biology for real
- x.com/EMBII4U/status/1727331097447428199 a love declaration to Marie Curie
Obsidian (software) Updated 2025-07-16
Good:
- WYSIWYG
- Extended-Markdown-based
- help.obsidian.md/Getting+started/Sync+your+notes+across+devices they do have a device sync mechanism
- it watches the filesystem and if you change anything it gets automatically updated on UI
- help.obsidian.md/links#Link+to+a+block+in+a+note you can set (forcibly scoped) IDs to blocks. But it's not exposed on WYSIWYG?
Bad:
- forced ID scoping on the tree as usual
- no browser-only editor, it's just a local app apparently:
- obsidian.md/publish they have a publish function, but you can't see the generated websites with JavaScript turned off. And they charge you 8 dollars / month for that shit. Lol.
- block elements like images and tables cannot have captions?
- they kind of have synonyms: help.obsidian.md/aliases but does it work on source code?
FFmpeg sound synthesis Updated 2025-07-16
Simple sines and variants:
- unix.stackexchange.com/questions/82112/stereo-tone-generator-for-linux/536860#536860
- stackoverflow.com/questions/5109038/linux-sine-wave-audio-generator/57610684#57610684
- superuser.com/questions/724391/how-to-generate-a-sine-wave-with-ffmpeg
- stackoverflow.com/questions/59551013/how-to-generate-stereo-sine-wave-using-ffmpeg-with-different-frequencies-for-eac/77730492#77730492
Ollama Updated 2025-07-16
Ollama is a highly automated open source wrapper that makes it very easy to run multiple Open weight LLM models either on CPU or GPU.
Its README alone is of great value, serving as a fantastic list of the most popular Open weight LLM models in existence.
Install with:
curl https://ollama.ai/install.sh | shOn P14s it runs on CPU and generates a few tokens per second, which is quite usable for a quick interactive play.
As mentioned at github.com/jmorganca/ollama/blob/0174665d0e7dcdd8c60390ab2dd07155ef84eb3f/docs/faq.md the downloads to under The file:gives a the exact model name and parameters.
/usr/share/ollama/.ollama/models/ and ncdu tells me:--- /usr/share/ollama ----------------------------------
3.6 GiB [###########################] /.ollama
4.0 KiB [ ] .bashrc
4.0 KiB [ ] .profile
4.0 KiB [ ] .bash_logout/usr/share/ollama/.ollama/models/manifests/hf.co/mlabonne/Meta-Llama-3.1-8B-Instruct-abliterated-GGUF/Q2_KWe can also do it non-interactively with:which gave me:but note that there is a random seed that affects each run by default. ollama-expect is an attempt to make the output deterministic.
/bin/time ollama run llama2 'What is quantum field theory?'0.13user 0.17system 2:06.32elapsed 0%CPU (0avgtext+0avgdata 17280maxresident)k
0inputs+0outputs (0major+2203minor)pagefaults 0swapsSome other quick benchmarks from Amazon EC2 GPU on a g4nd.xlarge instance which had an Nvidia Tesla T4:and on Nvidia A10G in an g5.xlarge instance:
0.07user 0.05system 0:16.91elapsed 0%CPU (0avgtext+0avgdata 16896maxresident)k
0inputs+0outputs (0major+1960minor)pagefaults 0swaps0.03user 0.05system 0:09.59elapsed 0%CPU (0avgtext+0avgdata 17312maxresident)k
8inputs+0outputs (1major+1934minor)pagefaults 0swapsIt tends to babble quite a lot by default, but eventually decides to stop.
nodejs/read_child_process_lines.js Updated 2025-07-16
react/ref-click-counter.html Updated 2025-07-16
Dummy example of using a React
ref This example is useless and to the end user seems functionally equivalent to react/hello.html.It does however serve as a good example of what react does that is useful: it provides a "clear" separation between state and render code (which becomes once again much less clear in React function components.
Notably, this example is insane because at:we are extracing state from some random HTML string rather than having a clean JavaScript variable containing that value.
<button onClick={() => {
elem.innerHTML = (parseInt(elem.innerHTML) + 1).toString()In this case we managed to get away with it, but this is in general not easy/possible.
riscv/timer.S Updated 2025-07-16
TODO: the interrupt is firing only once:
Adapted from: danielmangum.com/posts/risc-v-bytes-timer-interrupts/
Tested on Ubuntu 23.10:Then on shell 1:and on shell 2:GDB should break infinitel many times on
sudo apt install binutils-riscv64-unknown-elf qemu-system-misc gdb-multiarch
cd riscv
makeqemu-system-riscv64 -machine virt -cpu rv64 -smp 1 -s -S -nographic -bios none -kernel timer.elfgdb-multiarch timer.elf -nh -ex "target remote :1234" -ex 'display /i $pc' -ex 'break *mtrap' -ex 'display *0x2004000' -ex 'display *0x200BFF8'mtrap as interrupts happen. Find MAC address of a device on the other end of an Ethernet cable Updated 2025-07-16
Formal proof is useless Updated 2025-07-16
The only cases where formal proof of theorems seem to have had actual mathematical value is for theorems that require checking a very large number of case, so much so that no human can be fully certain that no mistakes were made. Some examples:
Functional Analysis I course of the University of Oxford 2023-2024 Updated 2025-07-16
Open access with solutions: courses.maths.ox.ac.uk/course/view.php?id=4988
Lecturer: Luc Nguyen
There are unlisted articles, also show them or only show them.