Gridworld Updated +Created
This is analogous to many traditional board games such as chess, the concept is very natural and maps well into computer.
The downsides of gridworld games are:
  • it is hard to model speed in discrete worlds. When you 10x faster, when do you collide with something else that is also crossing your path?
  • they tend to not use vector representations of objects. So to have an object be 10x longer than another one, the naive implementation has to add 10 smaller objects. This becomes untenable as the number of objects increases.
Gross hydrogen emission spectrum Updated +Created
One reasonable and memorable approximation excluding any fine structure is:
Equation 1.
Hydrogen spectral series mnemonic
.
see for example example: hydrogen 1-2 spectral line.
Group of American universities Updated +Created
Growth medium Updated +Created
Guerilla Open Access Manifesto by Aaron Swartz (2008) Updated +Created
Hmmm, he does not know how to spell guerilla? sic? www.quora.com/What-is-the-correct-spelling-guerilla-or-guerrilla
Note to self: if you are going to commit a crime, don't publish your plans online.
Ross Ulbricht's diaries come to mind.
That's how Russian shadow library maintainers do it, they know how to crime good old Russians. Maybe there is a good thing about having dictatorships in the world that give zero fucks about American copyright laws. There will always be some random Russian academic who will implement this and not go to jail. Maybe it's even state sponsored.
Guitar Updated +Created
The guitar is a highly imperfect instrument if compared to something like a piano, which is much more mathematically elegant.
However, Ciro Santilli just loves this imperfection for some reason, especially in the case of the electric guitar.
Bending, sliding and strumming just feel to good to not have.
And Ciro sucks are doing things in parallel, so the more single threaded approach of the guitar fits his brain/abilities better.
For those reasons, the electric guitar is Ciro's favorite musical instrument.
Guqin Updated +Created
Figure 2.
11th century painting of a guqin recital
. Source.
Figure 3.
Stringless guqin fan painting by Feng Chaoran (1943)
Stolen traight from www.silkqin.com/10ideo.htm on silkqin.com:
Wind in the pines and a babbling brook are nature's melody. A qin was brought along, but there is no need to play it
The The Gateless Barrier vibe and Chinese naturalism is just awesome.
Hall resistance Updated +Created
In some contexts, we want to observe what happens for a given fixed magnetic field strength on a specific plate (thus and are also fixed).
In those cases, it can be useful to talk about the "Hall resistance" defined as:
So note that it is not a "regular resistance", it just has the same dimensions, and is more usefully understood as a proportionality constant for the voltage given an input current:
This notion can be useful because everything else being equal, if we increase the current , then also increases proportionally, making this a way to talk about the voltage in a current independent manner.
And this is particularly the case for the quantum Hall effect, where is constant for wide ranges of applied magnetic field and TODO presumably the height can be made to a single molecular layer with chemical vapor deposition of the like, and if therefore fixed.
Hamilton's equations Updated +Created
Analogous to what the Euler-Lagrange equation is to Lagrangian mechanics, Hamilton's equations give the equations of motion from a given input Hamiltonian:
So once you have the Hamiltonian, you can write down this system of partial differential equations which can then be numerically solved.
Hanford site Updated +Created
The B Reactor of the facility produced the plutonium used for Trinity and Fat Man, and then for many more thousand bombs during the Cold War. More precisely, this was done at
Located in Washington, in a dry place the middle of the mountainous areas of the Western United States, where basically no one lives. The Columbia river is however nearby, that river is quite large, and provided the water needed by their activities, notably for cooling the nuclear reactors. It is worth it having look on Google Maps to get a feel for the region.
Unlike many other such laboratories, this one did not become a United States Department of Energy national laboratories. It was likely just too polluted.
Figure 1.
Aerial image of the Hanford site in 1960
. Source.
Hans Bethe Updated +Created
Head of the theoretical division at the Los Alamos Laboratory during the Manhattan Project.
Richard Feynman was working under him there, and was promoted to team lead by him because Richard impressed Hans.
He was also the person under which Freeman Dyson was originally under when he moved from the United Kingdom to the United States.
And Hans also impressed Feynman, both were problem solvers, and liked solving mental arithmetic and numerical analysis.
This relationship is what brought Feynman to Cornell University after World War II, Hans' institution, which is where Feynman did the main part of his Nobel prize winning work on quantum electrodynamics.
Hans must have been the perfect PhD advisor. He's always smiling, and he seemed so approachable. And he was incredibly capable, notably in his calculation skills, which were much more important in those pre-computer days.
Hans Petter Langtangen Updated +Created
It should be mentioned that when you start Googling for PDE stuff, you will reach Han's writings a lot under his GitHub Pages: hplgit.github.io/, and he is one of the main authors of the FEniCS Project.
Unfortunately he died of cancer in 2016, shame, he seemed like a good educator.
He also published to GitHub pages with his own crazy markdown-like multi-output markup language: github.com/hplgit/doconce.
Rest in peace, Hans.
Harvard University Updated +Created
Hermitian operator Updated +Created
This is the possibly infinite dimensional version of a Hermitian matrix, since linear operators are the possibly infinite dimensional version of matrices.
There's a catch though: now we don't have explicit matrix indices here however in general, the generalized definition is shown at: en.wikipedia.org/w/index.php?title=Hermitian_adjoint&oldid=1032475701#Definition_for_bounded_operators_between_Hilbert_spaces
Hertz electromagnetic wave experiments Updated +Created
Heinrich Hertz's main initial experiment used a spark-gap transmitter. It is not something that transmits recorded sounds like voice: it only transmits noisy beeps. And as such was used for wireless telegraphy.
Video 1.
Hertz Experiment on Electromagnetic Waves by Ludic Science (2015)
Source. Simplified recreation with cheap modern equipment. Uses as transmitter power source both:and the signal is observed on the receiver with a neon lamp
Video 2.
Hertz and Radio waves Explained by PhysicsHigh (2016)
Source. Simple schematics showing the basics of the experiments. No choice of components rationale.
Hewlett-Packard Updated +Created
They do seem to have been very innovative, and have had a very good work culture. They also had a huge impact on the Silicon Valley startup scene.
Some products they are known for:
Video 1.
The decline of HP by Company Man (2022)
Source.
Video 2.
HP Origins promotional documentary by HP (2006)
Source. A bit too star eyed, but gives some good ideas.
Hidden Answers Updated +Created
www.reddit.com/r/onions/comments/sfquss/hidden_answers_is_back/ gives pbqttnffb5sh6ckgnz4f5by55w25gd6tuw5f5qcctmnyk62eyhgx6rad.onion which is Dead Janary 2024
High flying bird vs gophers Updated +Created
Ciro once read that there are two types of mathematicians/scientists (he thinks it was comparing Einstein to some Jack of all trades polymath who didn't do any new discoveries):
  • high flying birds, who know a bit of everything, feel the beauty of each field, but never dig deep in any of them
  • gophers, who dig all the way down, on a single subject, until they either get the Nobel Prize, or work on the wrong problem and waste their lives
TODO long after Ciro forgot where he had read this from originally, someone later pointed him to: www.ams.org/notices/200902/rtx090200212p.pdf Birds and Frogs by Freeman Dyson (2009), which is analogous but about Birds and Frogs. So did Ciro's memory play a trick on him, or is there also a variant; of this metaphor with a gopher?
Ciro is without a doubt the bird type. Perhaps the ultimate scientist is the one who can combine both aspects in the right amount?
Ciro gets bored of things very quickly.
Once he understands the general principles, if the thing is not the next big thing, Ciro considers himself satisfied without all the nitty gritty detail, and moves on to the next attempt.
In the field of mathematics for example, Ciro is generally content with understanding cool theorem statements. More generally, one of Ciro's desires is for example to understand the significance of each physics Nobel Prize.
This is also very clear for example after Ciro achieved Linux Kernel Module Cheat: he now had the perfect setup to learn all the Linux kernel shady details but at the same time after all those years he finally felt that "he could do it, so that was enough", and soon moved to other projects.
If Ciro had become a scientist, he would write the best review papers ever, just like in the current reality he writes amazing programming tutorials on Stack Overflow.
Ciro has in his mind an overly large list of subjects that "he feels he should know the basics of", and whenever he finds something in one of those topics that he does not know enough about, he uncontrollably learns it, even if it is not the most urgent thing to be done. Or at least he puts a mention on his "list of sources" about the subject. Maybe everyone is like that. But Ciro feels that he feels this urge particularly strongly. Correspondingly, if a subject is not in that list, Ciro ignores it without thinking twice.
Ciro believes that high flying birds are the type of people better suited for venture capital investment management: you know a bit of what is hot on several fields to enough depth to decide where to place your bets and how to guide them. But you don't have the patience to actually go deeply into any one of them and deal with each individual shit that comes up.
Cosmos: A Personal Voyage (1980) episode 1 mentions as quoted by the Wikipedia page for Eratosthenes:
According to an entry in the Suda (a 10th-century encyclopedia), his critics scorned him, calling him beta (the second letter of the Greek alphabet) because he always came in second in all his endeavors.
That's Ciro.

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