Ciro Santilli @cirosantilli 37

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.

Group of rotations of a rigid body.

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.

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?

DokuWiki about physics, mostly/fully written by Jakob Schwichtenberg and therefore focusing on particle physics, although registration might be open to all.

Single chemical element, single phase (usually solid), but different 3D structures.

The prototypical examples are the allotropes of carbon such as diamond vs graphite.

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.

Some bibliography:

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.

Uniqueness: Uniqueness theorem for Poisson's equation.

There are actually two possible definitions for the DFT:

The $1/\sqrt{N}$ is nicer mathematically as the inverse becomse more symmetric, and power is conserved between time and frequency domains.

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.

A catalogue for Bitcoin can be found at: Section "Cool data embedded in the Bitcoin blockchain".

More info at: docs.ourbigbook.com#ourbigbook-web-topics