Greek root Updated +Created
MuJoCo getting started Updated +Created
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 -j
Now let's play. Minimal interactive UI simulation of a simple MJCF scene with one falling cube:
bin/basic ../doc/_static/hello.xml
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
Some 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.xml
A more advanced UI with a few controls:
bin/simulate ../doc/_static/hello.xml
Test soure code: github.com/google-deepmind/mujoco/tree/5d46c39529819d1b31249e249ca399f306a108ac/simulate. Mentioned at: mujoco.readthedocs.io/en/2.2.2/programming.html#sasimulate
A 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:
bin/simulate ../model/humanoid/humanoid.xml
under "Control" you move each joint of the robot separately which is quite cool.
Video 1.
Demo of MuJoCo's built-in simulate viewer by Yuval Tassa (2019)
Source.
There's also a 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
Mentioned at: mujoco.readthedocs.io/en/2.2.2/programming.html#sarecord but TODO that produced a broken video, related issues:
Paper without code Updated +Created
List of fluorescent proteins Updated +Created
Structure of the ribosome Updated +Created
QuantrolOx Updated +Created
Mitochondrial DNA mutates faster than nuclear DNA Updated +Created
Wikipedia mentions "Since animal mtDNA evolves faster than nuclear genetic markers" with a few sources.
Some sources:
Fire alarms Updated +Created
Kitchen: 2021-04: nine-volt battery battery at 8.79V. Not sounding.
Tarski's circle-squaring problem Updated +Created
Does not require straight line cuts.
The Harvest of a Century by Siegmund Brandt (2008) Updated +Created
This is a good book, it gives a summary of biographies, and a reasonable description of the main ideas, with many illustrations. Each subject is not presented in incredible detail, but it is a good overview of events.
Partial differential equation solver Updated +Created
Why it is hard to make money from this website Updated +Created
There is basically only one scalable business model in education as of the 2020's: helping teenagers pass university entry exams. And nothing else. Everything else is a "waste" of time.
Perhaps there is a little bit of publicity incentive to helping them win knowledge olympiads as well, but it is tiny in comparison, and almost certainly not a scalable investment. This may also depend on whether universities consider anything but exams, which varies by country.
That marked is completely saturated, and Ciro Santilli refuses to participate in it for moral reasons.
Beyond that, there is no scalable investment. Other non-scalable investments that could allow one to make a lifestyle business are:
  • extra-curricular initiatives to get younger children interested in science. These may have some money stream coming from the parents of the children. This happens because for young children, the parents are more in control, and the parents, unlike the students, have some money to spend. An example: www.littlehouseofscience.com/
    The space is also further crowded by several not-for profits.
    This business model is possible because experiments for young children may be cheap to realize, unlike any experiment that would matter to a teenager or adult.
  • creating a private university, for profit or not. Of course, at this point, you would be either:
    • competing against the reputation and funding of century old universities
    • or be offering more boring, lower tech or techless courses, to (God forbid the phrasing) "worse students", i.e. at a "worse university"
Teenagers and young adults:
  • don't have money to give you if you want to "help them learn for real"
  • are somewhat forced to obtain their "reputable university" reputation to kickstart their careers
It is this perfect storm that places this specific section of education in such a bad shape that it is today.
This project is likely to fail. It could become the TempleOS of wikis. The project' autism score is quite high. It might be an impossible attempt at a lifestyle business. But Ciro is beyond caring now. It must be done. Other things that come to mind:
Dangerous combination:
One man with a laptop and a dream.
and for any crazy person who might wish to join: Men Wanted for Hazardous Journey.
Video 1.
One Man's Dream - Ken Fritz Documentary (2021)
Source.
In some ways, Ciro was reminded of OurBigBook.com by this documentary. Ken built his ultimate audio system without regard to money and time, to enjoy until he dies. Ciro is doing something similar. There is one fundamental difference however: everyone can enjoy a website all over the world.
A bit ominous though that the whole thing was eventually sold off for a fraction of the building cost: www.washingtonpost.com/style/interactive/2024/ken-fritz-greatest-stereo-auction-cost/.
Parallel computing Updated +Created
Ionic compound Updated +Created
Fourier inversion theorem Updated +Created
A set of theorems that prove under different conditions that the Fourier transform has an inverse for a given space, examples:
Partial derivative notation Updated +Created
Lamb-Retherford experiment Updated +Created
Published as "Fine Structure of the Hydrogen Atom by a Microwave Method" by Willis Lamb and Robert Retherford (1947) on Physical Review. This one actually has open accesses as of 2021, miracle! journals.aps.org/pr/pdf/10.1103/PhysRev.72.241
Microwave technology was developed in World War II for radar, notably at the MIT Radiation Laboratory. Before that, people were using much higher frequencies such as the visible spectrum. But to detect small energy differences, you need to look into longer wavelengths.
This experiment was fundamental to the development of quantum electrodynamics. As mentioned at Genius: Richard Feynman and Modern Physics by James Gleick (1994) chapter "Shrinking the infinities", before the experiment, people already knew that trying to add electromagnetism to the Dirac equation led to infinities using previous methods, and something needed to change urgently. However for the first time now the theorists had one precise number to try and hack their formulas to reach, not just a philosophical debate about infinities, and this led to major breakthroughs. The same book also describes the experiment briefly as:
Willis Lamb had just shined a beam of microwaves onto a hot wisp of hydrogen blowing from an oven.
It is two pages and a half long.
They were at Columbia University in the Columbia Radiation Laboratory. Robert was Willis' graduate student.
Previous less experiments had already hinted at this effect, but they were too imprecise to be sure.
Larry Page's family Updated +Created

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