RSS Parrot

BETA

🦜 Collection of the Best Mathematics and Science Stuff | Abakcus

@abakcus.com.feed.birb@rss-parrot.net

I'm an automated parrot! I relay a website's RSS feed to the Fediverse. Every time a new post appears in the feed, I toot about it. Follow me to get all new posts in your Mastodon timeline! Brought to you by the RSS Parrot.

---

Abakcus is the best curation site for math and science. We work hard and curate the best articles, books, products, videos, and projects.

Your feed and you don't want it here? Just e-mail the birb.

Site URL: abakcus.com/feed@birb

Feed URL: abakcus.com/feed

Posts: 21

Followers: 3

Free Physics Textbooks from Universities and Physicists

https://abakcus.com/book-lists/free-physics-textbooks

Published: October 11, 2026 00:00

223 textbooks and lecture notes that physicists and universities give away, from a first look at motion to string theory, sorted by subject, level and kind.

The Coffer Illusion and the Sixteen Circles Between the Panels

https://abakcus.com/articles/coffer-illusion

Published: October 9, 2026 00:00

Sixteen circles sit in plain sight in Anthony Norcia's Coffer illusion, yet most of us see only rectangles. Line ends, shading, and the Pantheon's 140 coffers.

Math Symbols: Meaning, How to Read Them and LaTeX Code

https://abakcus.com/articles/math-symbols

Published: October 4, 2026 00:00

62 math symbols with their names, meaning, an example read aloud, LaTeX code, Unicode code point and who first put each one on paper.

29 Historic Math Books You Can Read for Free

https://abakcus.com/articles/historic-math-books

Published: October 3, 2026 00:00

From the Rhind Papyrus to Principia Mathematica, 29 historic math books that libraries have scanned and opened to everyone, each with a free link.

22 Original Math Papers You Can Read for Free

https://abakcus.com/articles/original-math-papers

Published: October 2, 2026 00:00

From Euler to Perelman, 22 papers that changed mathematics, each with its journal, language, page count and a free link to the original.

The History of Mathematics, Written in the Margins

https://abakcus.com/articles/history-of-mathematics

Published: October 1, 2026 00:00

From a student's clay tablet to the prize Perelman turned down, four thousand years of mathematics copied from hand to hand.

Free Math Textbooks from University Mathematicians

https://abakcus.com/book-lists/free-math-textbooks

Published: September 29, 2026 00:00

125 textbooks that mathematicians give away on their own pages, from high school algebra to graduate analysis, sorted by subject, level and format.

The Unit Circle Inside the 3-4-5 Triangle

https://abakcus.com/articles/3-4-5-triangle-incircle

Published: September 28, 2026 00:00

The largest circle that fits inside the right triangle with sides 3, 4 and 5 has a radius of exactly 1. There are three ways to see this, and the third one leads straight to the numbers 1, 2 and 3.

The USDA Pomological Watercolor Collection

https://abakcus.com/articles/usda-pomological-watercolor-collection

Published: September 27, 2026 00:00

In the years when photography could not hold a colour, the US Department of Agriculture hired painters to record the country's fruit, and fifty-six years later it was left with an archive of 7,497 pages.

1/998001: The Fraction That Lists Every Number but 998

https://abakcus.com/articles/1-998001

Published: September 26, 2026 00:00

Divide 1 by 998001 and every three-digit number from 000 to 999 falls out after the decimal point in order, all except one.

Swiss Cat Ladders: Bern's Zigzag Timber for Cats

https://abakcus.com/articles/swiss-cat-ladders

Published: September 17, 2026 00:00

In Bern people nail timber to their facades so the cat can reach the fourth floor. A designer photographed hundreds of them, and the zigzag costs no extra wood.

Matsuyama's Paradox: Pythagoras Hiding in a Puzzle

https://abakcus.com/articles/matsuyamas-paradox

Published: September 17, 2026 00:00

Four pieces and a small square make a square. Turn the pieces and they make the same square without it. Nothing is stretched, and the gap is Pythagoras.

Lissajous Curves Explained: From Tuning Forks to Lidar

https://abakcus.com/videos/lissajous-curves

Published: September 17, 2026 00:00

Tie two perpendicular oscillations to a single point and the point draws a pattern that tells you the ratio of the two frequencies, the phase between them, and how far they have drifted apart.

Kagen Sound's Puzzle Boxes: The Maze Is Not in the Box

https://abakcus.com/videos/kagen-sound-puzzle-boxes

Published: September 9, 2026 00:00

Kagen Sound builds wooden puzzle boxes with no nails and no metal parts. What he is actually building is a maze, and the maze is not on the box.

Pictures by #TheStormpilot

https://abakcus.com/books/stormpilot-santiago-borja

Published: September 8, 2026 00:00

A pilot who flies a thousand hours a year photographs the storms through his windshield. Ninety frames from 37,000 feet, with a meteorologist explaining each cloud.

The Future of the Responsible Company

https://abakcus.com/books/responsible-company-patagonia

Published: September 8, 2026 00:00

In 2022 Yvon Chouinard gave away a three-billion-dollar company. This is the book on how that decision got made — and on the fifty years of trying before it.

Who Owns the Fruit on an Overhanging Branch?

https://abakcus.com/articles/overhanging-branch-problem

Published: September 8, 2026 00:00

Roman law, an English court, the Turkish Civil Code and the Swedish constitution look at one branch crossing one fence and give four different answers.