Photon Updated 2025-07-16
Initially light was though of as a wave because it experienced interference as shown by experiments such as:
But then, some key experiments also start suggesting that light is made up of discrete packets:and in the understanding of the 2020 Standard Model the photon is one of the elementary particles.
This duality is fully described mathematically by quantum electrodynamics, where the photon is modelled as a quantized excitation of the photon field.
1914 Nobel Prize in Physics Updated 2025-07-16
Not only did this open the way for X-ray crystallography, it more fundamentally clarified the nature of X-rays as being electromagnetic radiation, and helped further establish the atomic theory.
Digits 0 to 9, white on black background:
for i in `seq 0 9`; do convert -size 512x512 xc:black -pointsize 500 -gravity center -fill white -draw "text 0,0 \"$i\"" $i.png; done
CRC-32 Updated 2025-07-16
Crystal radio Updated 2025-07-16
This was the first generation of commercially successful radios.
It uses a crystal detector as its diode, which is a crucial element of the radio, thus its name.
They were superseded by transistor radios, which were much more reliable, portable and could amplify the signal received.
Video 1.
How a Crystal radio Works by RimstarOrg
. Source.
Grepping the 2013 DNS Census first by overused CGI comms subdomains secure. and ssl. leaves 200k lines. Grepping for the overused "news" led to hits:
  • secure.worldnewsandent.com,2012-02-13T21:28:15,208.254.40.117
  • ssl.beyondnetworknews.com,2012-02-13T20:10:13,66.104.175.40
Also tried but failed:
OK, after the initial successes in secure., we went a bit more data intensive:
New results: only one...
  • 208.254.42.205 secure.driversinternationalgolf.com,2012-02-13T10:42:20,
After 2013 DNS Census virtual host cleanup heuristic keyword searches we later understood why there were so few hits here: the 2013 DNS Census didn't capture the secure. subdomains of many domains it had for some reason. Shame, because if it had, this method would have yielded many more results.
Codomain Updated 2025-07-16
Vs: image: the codomain is the set that the function might reach.
The image is the exact set that it actually reaches.
E.g. the function:
could have:
Note that the definition of the codomain is somewhat arbitrary, e.g. could as well technically have codomain:
even though it will obviously never reach any value in .
The exact image is in general therefore harder to characterize.
Coherence time Updated 2025-07-16
It takes time for the quantum state to evolve. So in order to have a deep quantum circuit, we need longer coherence times.

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