Git tips / Understand the commit tree Updated 2025-07-16
This is the most important thing to understand Git!
You must:
  • be able to visualize the commit tree
  • understand how each git command modifies the commit DAG
Perl HOWTO Updated 2025-07-16
Once upon a time, when Ciro Santilli had a job, he had a programming problem.
A senior developer came over, and rather than trying to run and modify the code like an idiot, which is what Ciro Santilli usually does (see also experimentalism remarks at Section "Ciro Santilli's bad old event memory"), he just stared at the code for about 10 minutes.
We knew that the problem was likely in a particular function, but it was really hard to see why things were going wrong.
After the 10 minutes of examining every line in minute detail, he said:
I think this function call has such or such weird edge case
and truly, that was the cause.
Option 1) git commit. Doh!!!
Option 2) git rebase. Basically allows you to do arbitrary modifications to the tree. The most important ones are:
Spacetime diagram Updated 2025-07-16
Why should I care when I can calculate new x and new time with Lorentz transformation?
Answer: it can give some qualitative intuition on what is larger/smaller happens before/after based only on arguably more intuitive geometric considerations, without requiring you to do any calculations, see e.g. Figure "Spacetime diagram illustrating how faster-than-light travel implies time travel".
List of tropes Updated 2025-07-16
Most of them use titles from TV Tropes.
Martial art Updated 2025-07-16
Quantum control system Updated 2025-07-16
Some people call it "operating System".
The main parts of those systems are:
Spacetime interval Updated 2025-07-16
In the Galilean transformation, there are two separate invariants that two inertial frame of reference always agree on between two separate events:
However, in special relativity, neither of those are invariant separately, since space and time are mixed up together.
Instead, there is a new unified invariant: the spacetime-interval, given by:
Note that this distance can be zero for two events separated.
Tor.link Updated 2025-07-16
Live January 2024.
Electronic band theory Updated 2025-07-16
How are the bands measured experimentally?
Why are there gaps? Why aren't bands infinite? What determines the width of gaps?
Bibliography:
Leonard Susskind Updated 2025-07-16
The bald confident chilled out particle physics guy from Stanford University!
One can't help but wonder if he smokes pot or not.
Also one can't stop thinking abot Leonard Hofstadter from The Big Bang Theory upoen hearing his name.
Figure 1.
Leonard Susskind lecturing in 2013
. Source.
Wang Jin (Water Margin character) Updated 2025-07-16
He used to train the 800,000 imperial guard troops at the Capital, much like Lin Chong. He's not one of the 108 Stars of Destiny.
Samurai cinema Updated 2025-07-16
Chanbara (チャンバラ).
Those movies are "all the same". A quasi lone superhuman samurai with a good inside but painful problems helping out random people, mostly villagers in trouble and bitches in debt.

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