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 Muhammad Ali Updated 2025-07-16
MUD (game genre) Updated 2025-07-16
MSc course of the University of Oxford Updated 2025-07-16
Mr. SQUID Updated 2025-07-16
This is the cutest product name ever.
Since 1992, Mr. SQUID has been the standard educational demonstration system for undergraduate physics lab courses.
YBCO device, runs on liquid nitrogen.
Moving magnet and conductor problem Updated 2025-07-16
In the above experiment:
- from the wire frame, the charge feels electromagnetic force, because it is moving and there is a magnetic field
- from the single charge frame, there is still magnetic field (positive charges are moving), but the body itself is not moving, so there is no force!
The solution to this problem is length contraction: the positive charges are length contracted and the moving electrons aren't, and therefore they are denser and therefore there is an effective charge from that frame.
This is also mentioned at David Tong www.damtp.cam.ac.uk/user/tong/em/el4.pdf (archive) "David Tong: Lectures on Electromagnetism - 5. Electromagnetism and Relativity" "5.2.1 Magnetism and Relativity".
Mountain used for cosmic ray experiments Updated 2025-07-16
Most important superconductor material Updated 2025-07-16
As of 2023 the most important ones economicaly were:The main application is magnetic resonance imaging. Both of these are have to be Liquid helium, i.e. they are not "high-temperature superconductor" which is a pain. One big strength they have is that they are metallic, and therefore can made into wires, which is crucial to be able to make electromagnetic coils out of them.
- Nb-Ti: the most widely used one. Used e.g. to create the magnetic fields of the Large Hadron Collider Up to 15 T.
- Nb-Sn: more expensive than Nb-Ti, but can reach up to 30 T.
Monero Updated 2025-07-16
Cryptocurrency with focus on anonymity. Was almost certainly the leading privacy coin since its inception until as of writing in the 2020s.
Ciro Santilli has received and held considerable quantities of Monero, notably 1000 Monero donation. so bias alert.
As mentioned at Section "Are cryptocurrencies useful?", Ciro Santilli believes that anonymity is the most valuable feature that really matters on crypto coins, and therefore if he were to invest in crypto, he would invest in Monero or some other privacy coin.
localmonero.co/knowledge/monero-stealth-addresses?language=en gives an overview of the privacy mechanisms:
- ring signatures, which hide the true output (sender)localmonero.co/knowledge/ring-signatures Gives an overview. Mentions that it is prone to heuristic attacks.Uses a system of decoys, that adds 10 fake possible previous outputs as inputs, in addition to the actual input.So the network only knows/verifies that one of those 11 previous outputs was used, but it does not know which one.TODO so how do you know which previous outputs were spent or not?
- RingCT which hides the amounts.
- stealth addresses, which hides who you send toThis forces receivers to scan try and unlock every single transaction in the chain to see if it is theirs or not.The sender therefore can know when the money is spent, but once again, not to whom it is being sent.
Based on en.wikipedia.org/wiki/CryptoNote and like Satoshi Nakamoto created by under the pseudonym "Nicolas van Saberhagen" www.reddit.com/r/Monero/comments/7v2obe/offering_a_bounty_for_a_video_of_the_speech_by/
Coinbase has actually stayed away from trading it even as of 2019 when Monero was the third largest market capitalization crypto because of fear of regulatory slashback: decrypt.co/36731/heres-why-coinbase-still-hasnt-listed-monero. Although it must be said, the value of privacy crypto is greatly reduced when everyone is trading it on exchanges, which require a passport upload to work.
Mond Laboratory Updated 2025-07-16
Monaco (editor) Updated 2025-07-16
Mole (unit) Updated 2025-07-16
Mole (espionage) Updated 2025-07-16
Molecular machine Updated 2025-07-16
The most beautiful ones:see also Section "Animations of molecular biology processes"
- sodium channel
- basically anything that falls in the DNA replication and transcription
Molecular biology technique Updated 2025-07-16
Molecular biology feels like systems programming Updated 2025-07-16
Whenever Ciro Santilli learns about molecular biology, he can't help but to feel that it feels like programming, and notably systems programming and computer hardware design.
In some sense, the comparison is obvious: DNA is clearly a programmable medium like any assembly language, but still, systems programming did give Ciro some further feelings.
- The most important analogy perhaps is observability, or more precisely the lack of it. For the computer, this is described at: The lower level you go into a computer, the harder it is to observe things.And then, when Ciro started learning a bit about biology techniques, he started to feel the exact same thing.For example when he played with E. Coli Whole Cell Model by Covert Lab, the main thing Ciro felt was: it is going to be hard to verify any of this data, because it is hard/impossible to know the concentration of each element in a cell as a function of time.More generally of course, this is exactly why making any biology discovery is so hard: we can't easily see what's going on inside the cell, and have to resort to indirect ways of doing so..This exact idea was highlighted by I should have loved biology by James Somers:
For a computer scientist, a biologist's methods can seem insane; the trouble comes from the fact that cells are too small, too numerous, too complex to analyze the way a programmer would, say in a step-by-step debugger.
And then just like in software, some of the methods biologists use to overcome the lack of visibility have direct software analogues:- add instrumentation to cells, e.g. GFP tagging comes to mind
- emulation, e.g. E. Coli Whole Cell Model by Covert Lab
- The boot process is another one. E.g. in x86 the way that you start in 16-bit mode, largely compatible into the 70's, then move to 32-bit and finally 64, does feel a lot the way a earlier stages of embryo development looks more and more like more ancient animals.
Ciro likes to think that maybe that is why a hardcore systems programmer like Bert Hubert got into molecular biology.
Some other people who mention similar things:
- I should have loved biology by James Somers highlights the computer abstraction layer analogy between the two:
Modus ponens Updated 2025-07-16
Modulo operation Updated 2025-07-16
Modulation Updated 2025-07-16
But now people want to send voice. How to do it?
It would not be practical without modulation: Why can't you send voice without modulation?
Modular multiplicative inverse Updated 2025-07-16
There are unlisted articles, also show them or only show them.