Interesting Links for 28-10-2025

[andrewducker]

1. Why Busy Beaver Hunters Fear the Antihydra

(tags:mathematics computers numbers )

2. Trump Defends Demolition Of Yggdrasil, Ancient Tree Of Life

(tags:satire politics USA )

3. No One Actually Knows What a Moon is

(tags:language space moon )

Comments

[simont]

#3: all these quasi-moons and pseudo-moons and so on remind me of the horribly confusing biological terminology for species of various levels of similarity to a type example, like "canids", "canins" and "caniforms", where nothing but constant practice will enable you to remember which is "very like a dog", which is "vaguely like a dog", and which is somewhere in between.

But my favourite fun fact from that article was the way Zoozve got its name, by a misreading of "2002 VE" and then the IAU decided, fine, the name could stick.

[andrewducker]

I love that story.

It's here for people who might be interested: https://threadreaderapp.com/thread/1750952860131729544.html

(I love being able to search my links)

[mellowtigger]

Yes, very interesting.

[bens_dad]

3. “Quasi-moons” are not actually very moonlike. These satellites can appear as if they are orbiting Earth, but in reality they are orbiting the sun.

I've seen that claimed for the Moon too: according to https://www.universetoday.com/articles/does-the-moon-orbit-the-sun, the Moon lies within the Earth's Hill Space - so it is orbiting the Earth, but the Moon's orbit around the Sun is convex - its journey around the sun is an ellipse with wiggles because of the Earth, and the Moon never goes "backwards" as it rotates around the Sun.

The Earth-Moon system is a "double-planet", which means that the Moon is close to being a planet, or at least a dwarf-planet, in its own right.

[mellowtigger]

I like the center-of-mass (outside the surface of either body) definition of a double planet. Wikipedia notes that the Earth-moon system will satisfy that criterion in a few billion years, as the moon glides farther away from Earth.

[juan_gandhi]

BB and Collatz... I'm absolutely impressed.
BB(7981) is unsolvable in principle (see this paper, that also compares BB with ZF set theory)

As to Yggdrasil... It's really not funny at all. Being a witness of an oncoming demise of the "land of the free", it's so sad.

[nancylebov]

3. Am I supposed to believe Trump would get all those words right?