optical illusions

Neuroscientist Beau Lotto runs the audience through color and pattern illusions to show that perception is shaped by context and evolutionary history rather than being a direct readout of the world. The talk is playful and hands-on, and it argues that the brain interprets ambiguous signals.

A two-hour NANOG tutorial by Richard Steenbergen aimed at network engineers, covering optical networking technologies. This is the updated 2017 edition of a recurring talk.

Huygens Optics explains the Fourier transform and shows how a lens performs one optically. A DLP projector is used as a Fourier filter to do simple pattern recognition on lithographic character patterns.

A five-minute demonstration of the Shepard tone, an audio illusion made from octave-separated tones that makes pitch seem to rise endlessly without ever getting higher.

A BBC Horizon clip demonstrating the McGurk effect, where the same audio sounds like different syllables depending on the mouth movements you see. It shows that people integrate visual speech information into what they hear.

Footage shot with a Nikon P1000 superzoom camera showing extreme optical zoom on distant targets from Ben Lomond in Scotland.

A Corning-sponsored video in which Adam Savage and Jamie Hyneman introduce flexible, bendable glass. It covers the history of glass innovation with demonstrations of bendable optical fiber and ultra-thin glass.

A short tour of a UK materials recycling facility showing how mixed recyclables are mechanically and optically sorted. Aluminum, ferrous metal, glass, paper, and trash come out as separate streams.

Numberphile visits Cliff Stoll, the man behind ACME Klein Bottles, and sees how he stores a thousand glass Klein bottles in a crawlspace under his house. A remote-controlled forklift fetches them.

A ten-minute card-magic act by Dani DaOrtiz performed on Penn & Teller: Fool Us in 2022. It is built on timing, misdirection and psychology, and the method defeated the show's hosts.

OK Go's music video for This Too Shall Pass, featuring a huge Rube Goldberg machine built in a warehouse in Los Angeles with Syyn Labs. The band interacts with the contraption in one continuous take.

Archer Lars Andersen demonstrates fast, accurate shooting techniques he says he revived from historical art and texts, arguing Hollywood archery is not historical.

A binaural audio demo, the 'Virtual Barber Shop', that places a barber moving around your head. It works best with headphones and closed eyes.

The Lock Picking Lawyer tests the supposedly unpickable lock designs built by the Stuff Made Here channel. He looks for bypasses and weaknesses in the novel anti-picking mechanisms.

Derren Brown's TV special in which he convinces a person he has a system for predicting horse race winners, demonstrating how survivorship bias and selective outcomes can fake predictive powers.

Mathematician Colin Wright demonstrates juggling and explains the mathematics of juggling patterns, including notation that led to new throwing patterns. It is a public presentation at the Museum of Mathematics aimed at a general audience.

Magician Kostya Kimlat performs a card trick on Penn & Teller: Fool Us that fooled the duo, using Penn's favorite card trick as a basis.

The original invisible gorilla awareness test by Daniel Simons and Christopher Chabris, in which viewers count basketball passes and often miss a gorilla crossing the scene. It demonstrates inattentional blindness.

A player piano is made to reproduce human speech, here reciting a European Environmental Criminal Court proclamation in German at the 2009 World Venice Forum. This upload adds subtitles so the words become understandable.

Mark Rober and collaborators build glitter bomb traps and other pranks to fight phone scam call centers, and share evidence about the operations.

A three-minute clip of magician Ricky Jay performing a card manipulation routine, including table faro shuffles. The routine builds in intensity and ends with a surprising finish.

A one-minute clip of Slavoj Zizek showing what he calls the official geographical limit between the Balkans and Central Europe, standing at a river in Ljubljana. It is a short, absurd and funny piece of cultural geography.

Hungarian folk dancers from Sapientia University act out the quicksort algorithm step by step, with music. It is part of the AlgoRythmics series of sorting algorithms performed as dance.

Arthur Ganson's kinetic sculpture chains twelve 1:50 worm gear reductions so the final gear, embedded in concrete, would take over two trillion years to turn once.

Wintergatan's video of the Marble Machine, a hand-built music instrument that plays a song using about 2000 marbles on a mechanical clockwork-style mechanism.

OK Go's music video for Needing/Getting, shot in the desert with a Chevy Sonic fitted with pneumatic arms that play over a thousand instruments across two miles.

Vsauce explores math through card tricks and big numbers, including an animation of how enormous 52 factorial, the number of deck orderings, really is.

A recorded phone call in which the Lenny bot, a looping set of prerecorded replies from a rambling old man, keeps a telemarketer on the line for 14 minutes. The uploader calls it the best Lenny call yet.

A two-minute BBC Horizon clip demonstrating the McGurk effect, where what you see of a speaker's mouth changes the sound you hear.

A short video of a man moving a 20 ton stone block by himself using wood and levers. It is part of a pyramid-mysteries channel.

Theo Jansen shows many of his Strandbeests, wind-powered walking kinetic sculptures, set to Khachaturian's Spartacus. It presents his work since 1990 on creating new forms of life on beaches.

Honda's 2003 'Cog' commercial for the Accord, a two-minute Rube Goldberg chain reaction of car parts. It was filmed practically rather than with CGI.

Mentalist Derren Brown plays nine skilled English chess players, including four grandmasters, simultaneously on his TV show. The trick behind the apparent win is the point of the segment.

Mark Rober and Joe Barnard drop an egg from a high-altitude balloon, using a camera-guided glider to steer it to a safe landing.

Stuntman Gary Connery jumps from a helicopter at 2,400 feet in a wingsuit and lands without a parachute on a runway of stacked cardboard boxes, the first such landing.

A one-minute clip of Alexander Overwijk drawing a near-perfect freehand circle, one metre across, in under a second on a chalkboard. He is a repeat winner of the World Freehand Circle Drawing Championship.

Penn and Teller help Rob Pike and Dennis Ritchie of Bell Labs play a prank on Nobel-winning physicist Arno Penzias. The clip shows the gag and its setup.

A short clip of a jet-powered flying lawnmower, the Sky Cutter, and related RC flying lawnmowers.

Mike Boyd takes up Smarter Every Day's challenge to learn to ride the Backwards Brain Bike, a bicycle whose steering is inverted, and rides 50 meters. It shows how hard it is to unlearn a motor skill.

A roughly one-minute TV clip in which a guest accidentally breaks a rare, one-of-a-kind wax cylinder recording on camera.