hand drying

SuperfastMatt looks at how the Tesla Model S retracting door handles were redesigned over time, from many parts to a motor plus sensor, with a focus on engineering and reliability.

A short animation that pairs the sound of a dialup modem handshake with a graphic explaining what each phase of the sound means.

Mark Handley of UCL looks at how SpaceX's November 2018 revisions to the Starlink constellation affect network behavior. The video visualizes the orbits and routing and estimates latencies, building on his earlier video and research paper.

A Technology Connections video essay on how analog and digital clocks shape different mental models of time, with the minute hand acting as a progress indicator.

Chubbyemu narrates the true case of a professor who spilled two drops of dimethylmercury on her hand and suffered fatal neurological damage.

Veritasium builds a QR code by hand to explain how it works. It covers the history of Morse code and barcodes, how QR codes encode data, why damaged codes still scan, and how safe they are.

Yuta asks whether native Japanese speakers can actually write kanji by hand, showing that many struggle to recall characters from memory.

CGP Grey's animated adaptation of The Dictator's Handbook, explaining how rulers stay in power by keeping a small group of key supporters happy rather than ruling fairly. It lays out selectorate theory and how resources shape regimes.

CGP Grey, adapting The Dictator's Handbook, explains how rulers keep power and why succession causes trouble when they die. It is the sequel to his video on the rules for rulers.

A short Coding Secrets episode explaining why hitting a Sonic 3D cartridge triggers a hidden level select. The cause was a custom crash handler that redirected CPU error interrupts to the level select screen.

Scott Manley surveys the research on whether people can adapt to rotating artificial gravity, from early Soviet centrifuge tests to modern studies. He concludes it is an engineering problem and discusses Coriolis effects and station radius.

Mark Handley of UCL explains, with simulation visualizations, how early Starlink satellites without inter-satellite links could still give low-latency wide-area communication by hopping via ground relays. He shows it can beat fibre on many long paths.

Tom Scott explains for Computerphile why handling time and timezones in code is so hard, walking through a simple web app that computes how long ago something happened. It covers the quirks of timezones and calendars and ends in an exasperated rant.

3Blue1Brown's first chapter on deep learning explains what neurons and layers are and the math underlying a basic neural network, using handwritten digit recognition with visual animations.

Kaze Emanuar explains how he rewrote and optimized the Super Mario 64 source code so it runs far faster on real N64 hardware. He covers performance bottlenecks and fixes in detail for his ROM hacks.

3Blue1Brown visualizes the Riemann zeta function and the analytic continuation that extends it beyond where its series converges, building toward the Riemann hypothesis.

Tom Scott explains for Computerphile how Unicode and UTF-8 grew out of messy older character encodings to become the web's standard. It covers why the design works and how it handles worldwide text.

A short BicycleDutch episode showing how people with disabilities use Dutch cycle tracks on hand-cycles, tricycles and mobility scooters.

A Vox Borders episode with Johnny Harris explaining how China is gradually erasing the line between mainland China and Hong Kong since the 1997 handover. It describes the one country, two systems arrangement and its expiration date.

Robert Miles explains reward modelling, in which an AI learns what humans want from their preference comparisons instead of a hand-written reward function. He walks through the 2017 paper on deep reinforcement learning from human preferences.

Pannenkoek explains how Super Mario 64 handles wall, floor and ceiling collisions, including triangles, normal vectors, quarter steps and out of bounds. It is a detailed 37-minute technical walkthrough of the game's physics.

Breaking Taps explains how the cryogenic mirror actuators on the James Webb Space Telescope achieve nanometer precision using flexures. It shows a 3D-printed replica and how one motor handles both coarse and fine motion.

Steve Mould explains homochirality: why biological molecules like sugars and amino acids come in only one handedness. He covers ideas about how this asymmetry might have arisen, touching on meteorite samples and RNA.

Kurzgesagt's animated explainer on CRISPR gene editing, covering how the technology works and what it could mean for curing disease, designer babies and aging. It frames genetic engineering as an irreversible change coming to humanity.

A short excerpt from Frans de Waal's TED talk showing a capuchin monkey fairness experiment in which two monkeys are paid unequally, one with cucumber and one with grapes. The shortchanged monkey reacts angrily.

Physicist Sabine Hossenfelder explains how 5G works and examines the health concerns around millimeter wave radiation. She reviews the scientific evidence and the open letters from scientists.

Tom Scott explains for Computerphile how floating point numbers work, why moving the binary point is fast, and why it handles money badly.

Veritasium's Derek Muller spends an hour in a silent, dark anechoic chamber at BYU to test the claim that 45 minutes is the most anyone can bear. He reports on his experience and other people's reactions.

A Veritasium video on survivor bias, explaining how an observed sample can be incomplete and skewed. It uses examples such as bombers and famous success stories.

Steve Mould shows Spintronics, a set of mechanical components such as resistors, capacitors and transistors linked by chains, that give an intuitive feel for how electrical circuits work.

A short clip of Richard Feynman explaining how a train stays on its tracks, through the conical shape of wheels and how it handles curves without differentials.

Short Curious Droid video on why NASA could not simply rebuild the Saturn V's Rocketdyne F-1 engine for the SLS boosters. It explains that the engines were hand-tailored and that much of the know-how was never documented, so the blueprints were not enough.

Practical Engineering explains how continuous welded rail copes with thermal expansion by restraining it, using the relationship between temperature, stress and strain. The video is part of a series on railways.