Software license that starts closed and becomes open once a certain amount of money is raised Updated 2025-04-24 +Created 1970-01-01
This is an interesting licensing model that might just scale.
In the Galilean transformation, there are two separate invariants that two inertial frame of reference always agree on between two separate events:
- time
- length, given by the Pythagorean theorem
However, in special relativity, neither of those are invariant separately, since space and time are mixed up together.
Note that this distance can be zero for two events separated.
CLI program implementing Universal Chess Interface: www.reddit.com/r/ComputerChess/comments/b6rdez/commandline_options_for_stockfish/
How to actually play against it: chess.stackexchange.com/questions/4353/how-to-install-stockfish-on-ubuntu So hard!
Quantum Computation and Quantum Information by Nielsen and Chuang Updated 2025-04-24 +Created 1970-01-01
Haven't found the one yet:
- open source software, doh
- end-to-end encryption...
- has browser frontend and Android app
- public URL without sharing your mobile phone: messaging software that force you to have a mobile phone
- self-destroying messages (turned on by default please)
- user base large enough to give some confidence that it was reviewed for security issues
- easy/built-in setup over Tor
Optional but really ideal:
- can delete messages from the device of the person you sent it to, no matter how old
- decentralized, your username is a public key
The state of messaging is ridiculous as of 2020.
Of course, because what we know about the halting problem, there cannot exist a single decider that decides all Turing machines.
E.g. The Busy Beaver Challenge has a set of deciders clearly published, which decide a large part of BB(5). Their proposed deciders are listed at: discuss.bbchallenge.org/c/deciders/5 and actually applied ones at: bbchallenge.org.
But there are deciders that can decide large classes of turing machines.
Many (all/most?) deciders are based on simulation of machines with arbitrary cutoff hyperparameters, e.g. the cutoff space/time of a Turing machine cycler decider.
The simplest and most obvious example is the Turing machine cycler decider
Bibliograpy:
- Losing Track by Channel 4 (1984), especially episode 5
- www.theguardian.com/uk/2013/mar/02/beeching-wrong-about-britains-railwaysToday the makeup of UK transport looks very different from the one envisaged by Dr Beeching. Rail passenger figures have almost doubled over the past 10 years; commuter trains are crammed; young people are deserting the car for the train; and Britain's railway bosses are struggling to meet soaring demands for seats. The legacy of Beeching - dug-up lines, sold-off track beds and demolished bridges - has only hindered plans to revitalise the network, revealing the dangers of having a single, inflexible vision when planning infrastructure."The crucial lesson to take from the Beeching anniversary is that you have to be flexible when planning transport infrastructure. Beeching was not," says Colin Divall, professor of rail history at York University. "Yes, many loss-making lines did need closing down, but nowhere near the number earmarked by Beeching, as we can now see with terrible hindsight."
Some further comments at: Section "Cataclysm: Dark Days Ahead".
Before
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After
. Added font awesome icons. github.com/ourbigbook/ourbigbook/issues/151
Didn't manage to subset, but so be it for now: stackoverflow.com/questions/62395038/how-can-i-export-only-one-character-from-ttf-woff-file-to-avoid-load-unnecessa/71197892#71197892
TODO understand.
Trapping Ions for Quantum Computing by Diana Craik (2019)
Source. A basic introduction, but very concrete, with only a bit of math it might be amazing:Sounds complicated, several technologies need to work together for that to work! Videos of ions moving are from www.physics.ox.ac.uk/research/group/ion-trap-quantum-computing.
- youtu.be/j1SKprQIkyE?t=217 you need ultra-high vacuum
- youtu.be/j1SKprQIkyE?t=257 you put the Calcium on a "calcium oven", heat it up, and make it evaporates a little bit
- youtu.be/j1SKprQIkyE?t=289 you need lasers. You shine the laser on the calcium atom to eject one of the two valence electrons from it. Though e.g. Universal Quantum is trying to do away with them, because alignment for thousands or millions of particles would be difficult.
- youtu.be/j1SKprQIkyE?t=518 keeping all surrounding electrodes positive would be unstable. So they instead alternate electrode quickly between plus and minus
- youtu.be/j1SKprQIkyE?t=643 talks about the alternative, of doing it just with electrodes on a chip, which is easier to manufacture. They fly at about 100 microns above the trap. And you can have multiple ions per chip.
- youtu.be/j1SKprQIkyE?t=1165 using microwaves you can flip the spin of the electron, or put it into a superposition. From more reading, we understand that she is talking about a hyperfine transition, which often happen in the microwave area.
- youtu.be/j1SKprQIkyE?t=1210 talks about making quantum gates. You have to put the ions into a magnetic field at one of the two resonance frequencies of the system. Presumably what is meant is an inhomogenous magnetic field as in the Stern-Gerlach experiment.This is the hard and interesting part. It is not clear why the atoms become coupled in any way. Is it due to electric repulsion?She is presumably describing the Cirac–Zoller CNOT gate.
- youtu.be/lJOuPmI--5c?t=1601 Cirac–Zoller CNOT gate was the first 2 qubit gate. Explains it more or less.
Introduction to quantum optics by Peter Zoller (2018)
Source. THE Zoller from Cirac–Zoller CNOT gate talks about his gate.- www.youtube.com/watch?v=W3l0QPEnaq0&t=427s shows that the state is split between two options: center of mass mode (ions move in same direction), and strechmode (atoms move in opposite directions)
- youtu.be/W3l0QPEnaq0?t=658 shows a schematic of the experiment
See also: e-learning website.
After something broke on the website due to SQLite vs PostgreSQL inconsistencies and took me a day to figure it out, I finally decided to update the test system so that
OURBIGBOOK_POSTGRES=true npm test will run the tests on PostgreSQL.Originally, these were being run only on SQLite, which is the major use case for OurBigBook CLI, which came before the website.
We know that superfluidity happens more easily in bosons, and so electrons joins in Cooper pairs to form bosons, making a superfluid of Cooper pairs!
Isn't that awesome!
There are unlisted articles, also show them or only show them.