Micro Bit simulator Updated 2025-07-16
Netflix and chill Updated 2025-07-16
On the Relative Motion of the Earth and the Luminiferous Ether Updated 2025-07-16
This paper is in the public domain and people have uploaded it e.g. to glorious Wikisource: en.wikisource.org/wiki/On_the_Relative_Motion_of_the_Earth_and_the_Luminiferous_Ether including its amazing illustrations.
Fig 3 from On the Relative Motion of the Earth and the Luminiferous Ether
. Source. Amazing 3D technical drawing from the 19th century!!! Continuous problems are simpler than discrete ones Updated 2025-07-16
Basically, continuity, or higher order conditions like differentiability seem to impose greater constraints on problems, which make them more solvable.
Some good examples of that:
- complex discrete problems:
- simple continuous problems:
- characterization of Lie groups
Khronos Group Updated 2025-07-16
Quantum field theory lectures Updated 2025-07-16
Discrete Fourier transform Updated 2025-07-16
Output: another sequence of complex numbers such that:Intuitively, this means that we are braking up the complex signal into sinusoidal frequencies:and is the amplitude of each sine.
- : is kind of magic and ends up being a constant added to the signal because
- : sinusoidal that completes one cycle over the signal. The larger the , the larger the resolution of that sinusoidal. But it completes one cycle regardless.
- : sinusoidal that completes two cycles over the signal
- ...
- : sinusoidal that completes cycles over the signal
Motivation: similar to the Fourier transform:In particular, the discrete Fourier transform is used in signal processing after a analog-to-digital converter. Digital signal processing historically likely grew more and more over analog processing as digital processors got faster and faster as it gives more flexibility in algorithm design.
- compression: a sine would use N points in the time domain, but in the frequency domain just one, so we can throw the rest away. A sum of two sines, only two. So if your signal has periodicity, in general you can compress it with the transform
- noise removal: many systems add noise only at certain frequencies, which are hopefully different from the main frequencies of the actual signal. By doing the transform, we can remove those frequencies to attain a better signal-to-noise
Sample software implementations:
- numpy.fft, notably see the example: numpy/fft.py
DFT of with 25 points
. This is a simple example of a discrete Fourier transform for a real input signal. It illustrates how the DFT takes N complex numbers as input, and produces N complex numbers as output. It also illustrates how the discrete Fourier transform of a real signal is symmetric around the center point. Animal flight Updated 2025-07-16
Flatpak Updated 2025-07-16
Base58 Updated 2025-07-16
Display device Updated 2025-07-16
Atomic, Molecular and Optical Physics Updated 2025-07-16
AMO is a slightly more general area than condensed matter physics, including related phenomena with smaller numbers atoms and optics. The two terms are however sometimes used as synonyms. The term AMO has gained wide usage and acceptability, see e.g.:
If Ciro had had greater foresight, this might have been what he studied at university!
Authy Updated 2025-07-16
Autodidacticism Updated 2025-07-16
There are two types of people:
- those who are autodidacts
- those who didn't really learn
Some possible definitions:
Thus OurBigBook.com.
Martial art Updated 2025-07-16
Average number of steps spent on a node of a Markov chain Updated 2025-07-16
TODO how to calculate
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:
- Applications of Quantum Mechanics by David Tong (2017) Chapter 2 "Band Structure"
Leonard Susskind Updated 2025-07-16
The bald confident chilled out particle physics guy from Stanford University!
Also one can't stop thinking abot Leonard Hofstadter from The Big Bang Theory upoen hearing his name.
Quantum control system Updated 2025-07-16
Some people call it "operating System".
The main parts of those systems are:
- sending multiple signals at very precise times to the system
- reading out some quantum error correction bits and sending error correcting signals back in a control loop
Quran character Updated 2025-07-16
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