LED spectrum Created 2024-06-26 Updated 2025-07-16
Type of laser Created 2024-06-26 Updated 2025-07-16
Lasers vs other light sources Created 2024-06-26 Updated 2025-07-16
The key advantages of lasers over other light sources are:
- lasers emit a narrow spectrum
- it can be efficient collimated, while still emitting a lot of output power: Section "Why can't you collimate incoherent light as well as a laser?"
- can be phase and polarization coherent, though it is not always the case? TODO.
One cool thing about lasers is that they rely on one specific atomic energy level transition to produce light. This is why they are able to to be so monchromatic. Compare this to:As such, lasers manage to largely overcome "temperature distribution-like" effects that create wider wave spectrum
- incandescent bulbs: wide black-body radiation spectrum
- LED: has a wider spectrum fundamentally related to an energy distribution, related: Why aren't LEDs monochromatic
- TODO think a bit about fluorescent lamps. These also rely on atomic energy transitions, but many of them are present at once, which makes the spectrum very noisy. But would individual lines be very narrow?
Crazy difference between 5W laser and 5W LED by Brainiac75
. Source. Baseic but good. Uses a laser photometer. Laser spectrum Created 2024-06-26 Updated 2025-07-16
Twisted pair Created 2024-06-26 Updated 2025-07-16
Education of André-Marie Ampère Created 2024-06-26 Updated 2025-07-16
en.wikipedia.org/w/index.php?title=Andr%C3%A9-Marie_Amp%C3%A8re&oldid=1211946256:TODO find the source for this.
Jean-Jacques Ampère, a successful merchant, was an admirer of the philosophy of Jean-Jacques Rousseau, whose theories of education (as outlined in his treatise Émile) were the basis of Ampère's education. Rousseau believed that young boys should avoid formal schooling and pursue instead a "direct education from nature." Ampère's father actualized this ideal by allowing his son to educate himself within the walls of his well-stocked library.
André-Marie Ampère Created 2024-06-26 Updated 2025-07-16
Electrical cable Created 2024-06-26 Updated 2025-07-16
One more more electrical wires surrounded by an insulator.
Oliver Heaviside Created 2024-06-26 Updated 2025-07-16
He participated in the development of the electrical telegraph, and he did some good modeling work that improved the foundations of the field, notably creating the telegrapher's equations.
He was one of those idealists who just want to do some cool work even if they have to starve for it, people had to get a state pension for him for his contributions. Nice guy. en.wikipedia.org/w/index.php?title=Oliver_Heaviside&oldid=1230097796#Later_years_and_views:He also never married: www.nndb.com/people/627/000204015/
In 1896, FitzGerald and John Perry obtained a civil list pension of £120 per year for Heaviside, who was now living in Devon, and persuaded him to accept it, after he had rejected other charitable offers from the Royal Society.
CIA 2010 covert communication websites 2013 DNS census secureserver.net MX records intersection 2013 DNS Census virtual host cleanup Created 2023-07-19 Updated 2025-07-16
We intersect 2013 DNS Census virtual host cleanup with 2013 DNS census MX records and that leaves 460k hits. We did lose a third on the the MX records as of 260 hits since secureserver.net is only used in 1/3 of sites, but we also concentrate 9x, so it may be worth it.
We did a full Wayback Machine CDX scanning for JAR, SWF and cgi-bin in those, but only found a single new hit:
- 63.130.160.50 theglobalheadlines.com. Just barely missed with our 2013 DNS Census virtual host cleanup heuristic keyword searches as we did think of both "global" and "headlines" in the "news" themes!
1973 Nobel Prize in Physics Updated 2025-07-16
Black holes nearest to the Sun Updated 2025-07-16
Interesting to note that there are quite a few nearer than Sagittarius A, as of 2022 we know of one at 1.5 kly: universemagazine.com/en/discovered-the-closest-black-hole-to-the-sun/
It is interesting that a few months earlier there seemed to be no known specific black holes in the Milky Way: www.nasa.gov/feature/goddard/2022/hubble-determines-mass-of-isolated-black-hole-roaming-our-milky-way-galaxy although their count is estimated to be in the hundreds of millions.
Phaser.js Updated 2025-07-16
Likely the best JavaScript 2D game engine as of 2023.Uses Matter.js as a physics engine if enabled. There's also an alternative (in-house?) "arcade" engine: photonstorm.github.io/phaser3-docs/Phaser.Physics.Arcade.ArcadePhysics.html but it appears to be simpler/less robust (but also possibly faster).
- github.com/photonstorm/phaser
- phaser.io/
- phaser.io/examples/v3.85.0/games contains the demo games
Phase transition Updated 2025-07-16
TODO can anything interesting and deep be said about "why phase transition happens?" physics.stackexchange.com/questions/29128/what-causes-a-phase-transition on Physics Stack Exchange
Photoelectric effect Updated 2025-07-16
No matter how hight the wave intensity, if it the frequency is small, no photons are removed from the material.
This is different from classic waves where energy is proportional to intensity, and coherent with the existence of photons and the Planck-Einstein relation.
Photoelectric effect by UCSB Physics Lecture Demonstrations (2021)
Source. Stone garden Updated 2025-07-16
The literal Chinese name says it all: "Fake Mountain". The stones evoke the feeling of the beautiful rock mountains of China.
The term "奇石假山" (qi2 shi2 jia3 shan1, lit. "weird shaped stone fake mountain") is also used, almost as a synonym by many people, since the stones are often chose in interesting shapes. Choosing the right stone is basically an art form in itself.
The stones used are generally limestone, which as a sedimentary rock is weaker, and more likely to be eroded into interesting shapes.
SuperCollider Updated 2025-07-16
How to play scores and save them to files is discussed at: doc.sccode.org/Guides/Non-Realtime-Synthesis.html
They have a nice looking IDE, but running anything from the command-line interface is super hard, much unlike Csound. How to get a decent hello world: stackoverflow.com/questions/65360414/how-to-play-a-supercollider-file-non-interactively-from-the-terminal-command-lin
Sample composition with custom synths + notes: sccode.org/1-5cl
leanpub.com/ScoringSound looks like a decent tutorial, it is basically the Csound FLOSS manual for SuperCollider.
Boitatech Updated 2025-07-16
Some people from them contacted Ciro Santilli after Ciro's initial publishing of CIA 2010 covert communication websites.
After a quick Discord chat with them, it was apparent that these people were really cool and knowledgeable.
Also many of them seem to think university is broken and just go hack straigh away.
Also they don't seem to need sleep. Go figure!
With pepole like this, there's hope for Brazil: Section "What poor countries have to do to get richer".
Cosmological event horizon Updated 2025-07-16
Kardashev scale Updated 2025-07-16
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