Spark-gap transmitter Updated +Created
The first type of device that allowed sending Morse code without wires, as opposed to the wired electrical telegraph that previously existed.
Naval communications was one of the first major applications, as you can't have wires on boats!
Wireless voice transmission came about with modulation.
Video 1.
Spark-gap transmitter at the at the The Museum of Radio and Technology Jeri Ellsworth (2017)
Source.
Special orthogonal group Updated +Created
Like orthogonal group but without reflections. So it is a "special case" of the orthogonal group.
This is a subgroup of both the orthogonal group and the special linear group.
Radio transmitter and receiver Updated +Created
Type of radioactive decay Updated +Created
Modulation Updated +Created
Modulation basically means encoding data on a carrier wave.
Image that we are at a point in history where spark-gap transmitters can send Morse code.
But now people want to send voice. How to do it?
It would not be practical without modulation: Why can't you send voice without modulation?
Physics Travel Guide Updated +Created
DokuWiki about physics, mostly/fully written by Jakob Schwichtenberg and therefore focusing on particle physics, although registration might be open to all.
Allotrope Updated +Created
Single chemical element, single phase (usually solid), but different 3D structures.
The prototypical examples are the allotropes of carbon such as diamond vs graphite.
Four-terminal sensing Updated +Created
Time dependent boundary condition Updated +Created
Most commonly, boundary conditions such as the Dirichlet boundary condition are taken to be fixed values in time.
But it also makes sense to think about cases where those values vary in time.
CoinGeek Updated +Created
news.ycombinator.com/item?id=14691623
CoinGeek is either run by or paid for by Craig Wright. You can see that all of the articles are either strongly in his favor or in line with his recent opinions.
ISO_8859-1 Updated +Created
Laplace's equation Updated +Created
Like a heat equation but for functions without time dependence, space-only.
TODO confirm: does the solution of the heat equation always converge to the solution of the Laplace equation as time tends to infinity?
In one dimension, the Laplace equation is boring as it is just a straight line since the second derivative must be 0. That also matches our intuition of the limit solution of the heat equation.
Normalized DFT Updated +Created
There are actually two possible definitions for the DFT:
Organization developing trapped ion quantum computer Updated +Created
Water Margin English translation Updated +Created
Inscription (blockchain) Updated +Created
Data that is inscribed in a blockchain as a way to perpetuate the data, rather than to follow the main intended purpose of the given blockchain, e.g. ASCII art instead of financial transactions on the Bitcoin blockchain.
OurBigBook topic feature Updated +Created
Schrodinger equation Hamiltonian Updated +Created
SHA-1 Updated +Created
Software developer collective Updated +Created
This model can work well when there is a set of commonly used libraries that some developers often use together, but such that there isn't enough maintenance work for each one individually.
So what people do is to create a group that maintains all those projects, to try and get enough money to survive from the contributions done primarily for each one individually.

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