🔗 Finds #29

Hello everyone, and welcome to issue #29 of Finds — the articles, sites, and corners of the web I bookmarked this week:

📄 Articles

theconversation.comWhat happens when a raindrop hits a puddle — A mathematician explains why puddle ripples spread into rings: in shallow water, surface tension beats gravity, so each wavelength travels at its own speed. Deep water loses the effect, which means the rings tell you how deep the puddle is.

🌐 Websites / blogs

longreads.comLongreadsFifteen years of picking the best long-form journalism and personal essays on the web, plus features it commissions itself. The Story Recommender is the way in: it hands you something to read when you don't know what you want.

aatishb.comMaking Music with MathAatish Bhatia uses the wave equation to synthesize a plucked, a struck and a bowed string, and each one plays in the page. It explains why a piano sounds harsher than a harp: a struck string's harmonics fade as 1/n, a plucked one's as 1/n².

mathpages.comMathPagesKevin Brown's decades-old, very plain-looking archive of short essays on number theory, geometry, probability, physics and the history of maths. The relativity section, Reflections on Relativity, is a whole book, and it's now in its second edition in print.

📺 From YouTube

youtube.comJohnny Harris — An independent filmmaker with 8 million subscribers and 537 videos explaining how the world works: money, borders, the American war machine. Each one starts from a plain question, like his recent 'I don't get democracy', and works through maps until it has an answer.

youtube.comThe Insane Real Engineering of the Nazi Enigma Machine — Veritasium films at Bletchley Park to tell the whole story, from the Polish codebreakers who cracked Enigma first to Turing's Bombe. It ends by leaving you a Naval Enigma message that has never been decrypted.

youtube.comEvery Car Term & Its Meaning Explained in 17 Minutes — A countdown of 28 car parts and terms, from the muffler to the mass air flow sensor. The best one is horsepower: James Watt made the unit up to sell steam engines, and he underestimated the horse.

🌱 Promoted to the wiki: these now live on their topic pages — Physics, Essays, Mathematics, General Knowledge, Cryptography, and Engines — so they’re easy to find later. 🗂️ Catch up on past issues.