Welcome to math, where everything is cool if you know how it works

October 18, 2018 3:40 PM

Geometry is neat:
Surface Area of a Sphere
Cake by Dinara Kasko
Morphing Cube
Slowly Filling a Maze
Pop-up cards
Milling Machine At Work
Church in Mogno, Switzerland
Two inverted magnetic bowls causing un-magnetized steel balls to organize into geometric patterns

Mandala Creator
Solar Photovoltaic Farm in France
Balanced coins
Hilbert curve
Rainy day in Tokyo
Let's trips
Cross Bridge Waltz
By Étienne Jacob
Hundreds more, mostly gifs, at the r/GeometryIsNeat subreddit

posted by growabrain (14 comments total)

The steel balls between the bowls seem terrified!
posted by Splunge at 3:48 PM on October 18, 2018 [1 favorite]

OMG YES, showing this to my math fearing father. See, Dad? See why I like this???
posted by Abehammerb Lincoln at 3:56 PM on October 18, 2018 [1 favorite]

Did...did you just turn the surface area of a sphere into the area under the curve of a sine-wave?
WITCHCRAFT, BLACK MAGIC I SAY!
posted by The Legit Republic of Blanketsburg at 4:04 PM on October 18, 2018 [4 favorites]

Venus Flytrap Explains the Structure of an Atom
posted by The Underpants Monster at 4:17 PM on October 18, 2018 [3 favorites]

Thanks for these. I watched the milling several times. I've never really got math, but things like these make it real. The Sketchup sphere flattening one is so elegant.
posted by unearthed at 4:26 PM on October 18, 2018 [1 favorite]

Procedural symbols drawn by a mechanical plotter that uses a Lamy fountain pen (and Lamy blue ink). I've never heard of a plotter that uses an honest to god fountain pen.
posted by ardgedee at 4:33 PM on October 18, 2018 [3 favorites]

I liked the Lemarchand Configuration solving itself.

“We have such... topologies... to show you.”
posted by GenjiandProust at 5:11 PM on October 18, 2018 [1 favorite]

This doesn't help me with my stupid Calculus homework today.
posted by rhizome at 7:38 PM on October 18, 2018 [3 favorites]

Oh, one of *those* people, huh?

When I was a kid, I liked to take a strip of paper (cut a half-inch off the edge of a sheet of paper), twist one end 180 degrees, and then tape the two ends together. Then I'd walk up to a victim and say "this only has one side". They'd say something like "no way" or "you're nuts". Then I'd give them a pencil and say "draw a line around the middle of one side."

For the big finish? Hand them a pair of scissors and say, "Okay, now cut it along your line."
posted by Twang at 7:46 PM on October 18, 2018 [2 favorites]

my wife teaches math so some high-schoolers are definitely gonna see these.
posted by wellifyouinsist at 9:27 PM on October 18, 2018

OK, math people, what is wrong with this reasoning:

Let's find the surface area of a hemisphere. Taking infinitely many thin slices of the hemisphere, each of which has an area of 2*pi*r, the circumference, times dr, the height, it looks to me like the whole thing is an integral of 2*pi*r, which is, iirc, pi* r^2. Adding that to the other hemisphere, I get a surface area of 2* pi* r^2, which is half of what the correct formula really is. Please hope me!
posted by thelonius at 3:52 PM on October 19, 2018

thelonius: here's an explanation of why that argument doesn't work. The short answer is that the slices don't have a height of dr—it's a more complicated expression than that.
posted by panic at 6:23 PM on October 20, 2018 [1 favorite]

thanks! I was thinking about that earlier today
posted by thelonius at 6:28 PM on October 20, 2018

This is beautiful, thank you.
posted by seyirci at 7:29 AM on October 24, 2018