wiki.bbchallenge.org/wiki/Antihydra:
- news.ycombinator.com/item?id=40864949 BB(6), The 6th Busy Beaver Number, is harder than a Collatz-like math problem
- www.reddit.com/r/math/comments/1dubva0/finding_the_6th_busy_beaver_number_%CF%836_aka_bb6_is/ "Finding the 6th busy beaver number (Σ(6), AKA BB(6)) is at least as hard as a hard Collatz-like math problem called Antihydra":
- www.reddit.com/r/compsci/comments/1duc62e/finding_the_6th_busy_beaver_number_%CF%836_aka_bb6_is/
The good:
- a bit of Students must be allowed to progress as fast as they want. Though not fully as once you're in your stuck for 6 weeks in their rythm. Though there are research projects going on too which helps.
- Peer tutoring-like: they seem to pick undergraduate students to serve as supervisors
The bad: everything else. Closed source learning materials + a university-like selection program. Such a waste of efforts that could benefit way more people with more open resources.
meta.mathoverflow.net/questions/4889/request-to-keep-an-eye-out-for-promys-admissions-problems asking to remove PROMYS problems from MathOverflow. And it seems to have been mostly accepted. Newbs. Any maths problem should be allowed to be askeable online. There are no fundamentally new problems, copyright takedown is just silly.
The Abstraction and Reasoning Challenge by 
Ciro Santilli 35 Updated 2024-12-15 +Created 2024-07-04
Ciro Santilli 35 Updated 2024-12-15 +Created 2024-07-04
Standing wave caused by wave interference of two waves
. Source. Staring from a triangle wave, this explains why we always get the same musical notes:See also: solving partial differential equations with the Fourier series.
- www.math.hmc.edu/~ajb/PCMI/lecture7.pdf "7.5.1. Musical instruments" is very good. Also mentions that in the piano it is more like an initial speed is applied, and it is not the same as plucking
- music.stackexchange.com/questions/135635/confusion-about-overtones-and-a-slow-motion-video-of-a-plucked-string
- music.stackexchange.com/questions/60833/what-determines-the-relative-volumes-of-the-harmonics-when-plucking-a-guitar-str
TODO: do higher overtones decay faster in time than the base ones?
- www.physicsforums.com/threads/why-do-harmonics-decay-faster-than-the-fundamental.955731/ But presumaby yes, damping force is proportional to speed, and higher harmonics have higher speeds going up and down
Wave equation on string with one vibrating side by Ciro Santilli 35 Updated 2024-12-15 +Created 2024-07-04
Ciro Santilli 35 Updated 2024-12-15 +Created 2024-07-04You know things are bad when the extracurricular activities are what studnets should actually be doing full time instead!
The FASCINATING 200-Year History of Benzene by Chemistorian
. Source. Interesting history. Notably how things were only finally well settled by X-ray crystallography.Discovering them was not so easy because they don't form chemical compounds. So they exist only as gases. And Helium disperses off into space.
Argon was the first to be found by density considerations because it is so abundant on Earth's atmosphere (~1%): Argon is abundant on Earth's atmosphere because it comes from the decay of Potassium-40.
Then basically all of the others were discovered by spectral lines. Helium notably was first found on the Sun like that, and only later on Earth! Thus its name. Pretty cool.
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