Superfluid helium Updated +Created
Two different Lie groups can have the same Lie algebra Updated +Created
The most important example is perhaps and , both of which have the same Lie algebra, but are not isomorphic.
W Updated +Created
x86 Paging Tutorial / Why not a balanced tree Updated +Created
Learned readers will ask themselves: so why use an unbalanced tree instead of balanced one, which offers better asymptotic times en.wikipedia.org/wiki/Self-balancing_binary_search_tree?
Likely:
  • the maximum number of entries is small enough due to memory size limitations, that we won't waste too much memory with the root directory entry
  • different entries would have different levels, and thus different access times
  • tree rotations would likely make caching more complicated
Y Updated +Created
Z Updated +Created
Et aliī Updated +Created
F Updated +Created
Harmonic function Updated +Created
I Updated +Created
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Josephson junction Updated +Created
A device that exhibits the Josephson effect.
Figure 1.
Electron microscope image of a Josephson junction its I-V curve
. Source.
K Updated +Created
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Ordnance Survey Updated +Created
Has some of the best map data available for the United Kingdom, but their data appears to be proprietary?
Sic Updated +Created
The development cycle time is your God Updated +Created
A slow development test cycle will kill your software.
New developers won't want to learn your project, because they would rather shoot themselves.
This means that build time, and the time to run tests, must be short.
5 seconds to rebuild is the maximum upper limit.
Of course, at some point software gets large enough that things won't fit anymore in 5 seconds. But then you must have either some kind of build caching, or options to do partial builds/tests that will bring things down to that 5 second mark.
You also have to spend some time profiling execution and build from scratch times.
A slow build from scratch will mean that your continuous integration costs a lot, money that could be invested in a new developer!
It also means that people won't bother to reproduce bugs on given commits, or bisect stuff.
One anecdote comes to mind. Ciro Santilli was trying to debug something, and more experience colleague came over.
To reproduce a problem, ciro was running one command, wait 5 seconds, run a second command, wait 5 seconds, run a third command:
cmd1
# wait 5 seconds
cmd2
# wait 5 seconds
cmd3
The first thing the colleague said: join those three commands into one:
cmd1;cmd2;cmd3
And so, Ciro was enlightened.
Figure 1.
xkcd 303: Compiling
. Source. They should be benchmarking and fixing their shitty build system instead.
2007 Nobel Prize in Physics Updated +Created
2023 Nobel Prize in Chemistry Updated +Created
Cardano Updated +Created
This was getting very hot as of 2022 for some reason. Would be good to understand why besides the awesome name.

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