Ciro Santilli @cirosantilli 35

If you point a light detector to any empty area of the sky, you will still get some light.

The existence of this is quite mind blowing, since "there is nothing there emitting that light".

To make sense of how it is possible to see this light, you can think of the universe as the expanding raisin bread model, but it expands faster than light (thus the existence of the cosmological event horizon), so we are still receiving light form the middle, not the borders.

CMB is basically perfectly black-body radiation at 2.725 48 K, but it has small variations with variations of the order of 200 microKelvin: cosmic microwave background anisotropy.

Technique to solve partial differential equations

Naturally leads to the Fourier series, see: solving partial differential equations with the Fourier series, and to other analogous expansions:

One notable application is the solution of the Schrödinger equation via the time-independent Schrödinger equation.

Bibliography:

Unfortunately, physicists and mathematicians keep using Greek letters in their formulas, so we just have to learn them.

A helpful way to remember is to learn a bit of their history/pronunciation: Section "Historical correspondence between Latin and Greek".

To learn the greek letters if you have a base latin alphabet, you must learn the sound of each letter, and which Latin letters they correspond to.

Symbols that look like Greek letters but are not Greek letters:

Is Ciro Santilli crazy (he is, but for this point specifically), or do many/most Greek letters represent the mouth position used in the pronunciation of the letter?

Related:

cyclotrons produce the better images, but they are expensive/you have to move to them and order a timeslot.

Lab-based just use some X-ray source from the lab, so it is much move convenient e.g. for a pharmaceutical company doing a bunch of images. The Wikipedia image shows such a self-contained lab system: en.wikipedia.org/wiki/File:Freezed_XRD.jpg

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