Alternative splicing Updated +Created
Angstrom Updated +Created
Effect of a change of basis on the matrix of a bilinear form Updated +Created
If is the change of basis matrix, then the matrix representation of a bilinear form that looked like:
then the matrix in the new basis is:
Sylvester's law of inertia then tells us that the number of positive, negative and 0 eigenvalues of both of those matrices is the same.
Proof: the value of a given bilinear form cannot change due to a change of basis, since the bilinear form is just a function, and does not depend on the choice of basis. The only thing that change is the matrix representation of the form. Therefore, we must have:
and in the new basis:
and so since:
Mind blown Updated +Created
Video 1.
The Universe I, II & III | Tim and Eric Awesome Show by Adult Swim UK (2017)
Source. This amazing video contains the best mind blown meme ever, Ciro Santilli almost shat himself when he first watched it.
Renormalization Updated +Created
Video 1.
The Biggest Ideas in the Universe | 11. Renormalization by Sean Carroll (2020)
Source. Gives a very quick and high level overview of renormalization. It is not enough to satisfy Ciro Santilli as usual for other Sean Carroll videos, but it goes some way.
Experimental Evidence for Quantized Flux in Superconducting Cylinders Updated +Created
The first published experimental observation of the magnetic flux quantum.
The paper that follows it in the journal is also of interest, "Theoretical Considerations Concerning Quantized Magnetic Flux In Superconducting Cylinders" by N. Byers and C. N. Yang, it starts:
In a recent experiment, the magnetic flux through a superconducting ring has been found to be quantized in units of ch/2e. Quantization in twice this unit has been briefly discussed by London' and by Onsager. ' Onsager' has also considered the possibility of quantization in units ch/2e due to pairs of electrons forming quasi-bosons.
So there was some previous confusion about the flux quantum due to the presence of Cooper pairs or not.
Figure 1. . The legend reads:
(Upper) Trapped flux in cylinder No. 1 as a function of magnetic field in which the cylinder was cooled below the superconducting transition. temperature. The open circles are individual data points. The solid circles represent th, e average value of all data points at a particular value of applied field including all the points plotted and additional data which could not be plotted due to severe overlapping of points. Approximately two hundred data points are represented. The lines are drawn at multiples of hc/2e.
(Lower) Net flux in cylinder No. 1 before turning off the applied field in which it was cooled as a function of the applied field. Open and solid circles have the same significance as above. The lower line is the diamagnetic calibration to which all runs have been normalized. The other lines are translated vertically by successive steps of hc/2e.
Figure 2. . The legend reads:
(Upper) Trapped flux in cylinder No. 2 as a function of magnetic field in which the cylinder was cooled below the superconducting transition temperature. The circles and triangles indicate points for oppositely directed applied fields. Lines are drawn at multiples of hc/2e.
(Lower) Net flux in cylinder No. 2 before turning off the applied field as a function of the applied field. The circles and triangles are points for oppositely directed applied fields. The lower line is the diamagnetic calibration to which all runs have The other been normalized. lines are translated vertically by successive steps of hc/2e.
Gauge theory Updated +Created
The term and idea was first introduced initialized by Hermann Weyl when he was working on combining electromagnetism and general relativity to formulate Maxwell's equations in curved spacetime in 1918 and published as Gravity and electricity by Hermann Weyl (1918). Based on perception that symmetry implies charge conservation. The same idea was later adapted for quantum electrodynamics, a context in which is has even more impact.
Heisenberg picture Updated +Created
Basically the same as matrix mechanics it seems, just a bit more generalized.
Magnetic dipole moment Updated +Created
Micro Bit example Updated +Created
Not safe for work Updated +Created
nRF51 series Updated +Created
Pandoc Updated +Created
This is good software.
If it only it were written in JavaScript instead of Haskell (!?), then Ciro might have used it as the basis for OurBigBook Markup.
Carrier wave Updated +Created
Early transmitters such as the spark-gap transmitter could only send noises to send Morse code.
To send voice and music, amplitude modulation had to be developed. And a key ingredient of this is the carrier wave.
The problem is, the carrier wave needs to have somewhat high frequencies, in the hundreds of kHz TODO why. But as you might imagine, that is hard to achieve by mechanical means such as a hand cranck like Hippolyte Pixiis alternator!
Interestingly, some of the first carrier wave generators were actually mechanical, e.g. the Alexanderson alternator.
But clearly such mechanical machines were not very scalable, and soon more electronic devices were introduced, notably the vacuum tube.
Compile MicroPython code for Micro Bit locally Updated +Created
To use a prebuilt firmware, you can just use uflash, tested on Ubuntu 22.04:
git clone https://github.com/bbcmicrobit/micropython
cd micropython
git checkout 7fc33d13b31a915cbe90dc5d515c6337b5fa1660
uflash examples/led_dance.py
What that does is:
To build your own firmware see:
Fructose Updated +Created
Mahayana sutra Updated +Created

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