As of 2020, no one knows how to build the major desktop distros fully from source into the ISO, and especially so in a reproducible build way. Everything is done in build servers somewhere with complicated layers of prebuilds. It's crap.
Spacelike-separated event Updated 2025-07-16
Mathematically, we can decide if two events are timelike-separated or spacelike-separated by just looking at the sign of the spacetime interval between them.
On the light cone, these are events on the left/right part of the cone.
Different observers might not agree on the order of two spacelike-separated events.
Further discussion at Section "Light cone".
The opposite of those events are timelike-separated events.
Wave-particle duality Updated 2025-07-16
The history of light if funny.
But then evidence of the diffraction of light start to become unbearably strong, culminating in the Arago spot.
And finally it was understood from Maxwell's equations that light is a form of electromagnetic radiation, as its speed was perfectly predicted by the theory.
But then evidence of particle nature started to surface once again with the photoelectric effect. Physicists must have been driven mad by all these changes.
Light source Updated 2025-07-16
Optical fiber Updated 2025-07-16
Video 1.
The Story of Light by Bell Labs (2015)
Source. Gives some ideas of the history of fiber optics. Features: Herwig Kogelnik.
Video 3. . Source. 2008 at MIT. Theory and demonstration.
Photometer Updated 2025-07-16
Spectroscopy Updated 2025-07-16
Fraunhofer diffraction Updated 2025-07-16
Far field approximation to Kirchhoff's diffraction formula, i.e. when the plane of observation is far from the object diffracting.
Fresnel diffraction Updated 2025-07-16
Near field approximation to Kirchhoff's diffraction formula, i.e. when the plane of observation is near the object diffracting.

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