collimated light

Dr. Roger Seheult of MedCram reviews the benefits of sunlight beyond vitamin D, covering the solar spectrum, circadian rhythm, melatonin and infrared light. The lecture runs nearly two hours with timestamps.

Veritasium explains why the one-way speed of light has never been measured, only the round-trip speed, since measuring it requires synchronized clocks that assume the answer. It explores the implications for relativity.

Technology Connections examines why light bulbs have the lifespans they do, including the real history of the Phoebus cartel. He shows that bulb life trades off against brightness and efficiency rather than being simple planned obsolescence.

A PBS clip in which Richard Feynman explains the strange nature of light and electromagnetic radiation. He conveys how little of it we actually see and how radio waves are present everywhere.

DIY Perks shows how to turn old or smashed TVs and monitors into realistic artificial window lights, using the backlight and Fresnel lens to simulate distant daylight.

Technology Connections experiments with filtering white and colored LEDs to make holiday lights look less garish. He explains why narrowband LED strings look harsh compared with incandescent bulbs.

Technology Connections explains why American cars all had the same standardized sealed-beam headlights until 1957. It covers the regulations behind the design and the effect on night visibility.

Sabine Hossenfelder explains why she thinks faster-than-light travel may not be ruled out. She argues that the standard objections from special relativity are inconclusive.

An 8-minute explainer on the Lightning Network and how it relates to Segwit, Bitcoin and Litecoin. It covers how off-chain payment channels route payments to scale blockchain transactions.

Rick Falkvinge responds to viewer feedback on his earlier Lightning Network video and raises a flaw he says was not previously discussed. The main thread is the network's unsolved routing problem.

A short look at CoeLux, an artificial skylight that recreates the scattering process that makes the sky look blue, producing a convincing illusion of distant sun and depth.

A SIGGRAPH 2013 demo from Douglas Lanman and NVIDIA of near-eye light field displays, which allow much thinner head-mounted displays that still show accurate focus and depth cues.

A 2017 video arguing that banks and Blockstream steered Bitcoin toward the Lightning Network. It is partisan commentary from the Bitcoin Cash side of the scaling dispute.

AlphaPhoenix shows off a new camera that films at two billion frames per second and uses it to film a laser pointer pulse. He investigates a strange quirk in how the speed of light appears on camera.

Technology Connections complains about the harsh, overly blue color of modern LED Christmas lights and tries more fixes for them. It follows earlier videos by the same creator on holiday lighting.

DIY Perks builds a realistic artificial sun for dark winters, using a powerful water-cooled LED, a satellite dish reflector for near-parallel rays, and a scattering layer to mimic the blue sky. The video explains the optics behind why most lamps do not look like sunlight and shows the build and its results.

Technology Connections explains how LED traffic lights, which do not melt snow, drew complaints and were blamed for accidents. He uses it to illustrate the 'but sometimes' fallacy against new technology.

A PyCon 2013 block of Friday evening lightning talks. It includes the debut of Hy, a Lisp dialect that compiles to Python AST, and Solomon Hykes's first public talk on Docker.

Professor Mike Merrifield of Nottingham explains in a mostly uncut conversation why light travels slower in glass. He treats light as a wave and describes how the material's electrons produce secondary waves that combine to slow it.

A Microsoft Flight Simulator Feature Discovery episode in which CEO Sebastian Wloch explains the new aerodynamics simulation for the 2020 release.

An American Airlines training video by Captain Warren VanderBurgh on control malfunctions and flight instrument anomalies. It discusses real incidents such as runaway trim and instrument failures and how crews should respond.

PBS Space Time argues that the speed of light is better understood as the speed of causality, the universal limit on how fast cause and effect propagate. Light travels at that speed because it is massless, but the limit itself is a property of spacetime.

3Blue1Brown visualizes Feynman's lecture on the refractive index, explaining why light appears to slow down in glass and why the effect depends on color. It builds the idea from waves produced by oscillating charges in the material.

Fermilab's Don Lincoln explains why light travels slower in water and glass. He knocks down common wrong explanations such as absorption and re-emission, then gives the wave-mechanics reason tied to refractive index.

ScienceClic explains why nothing can go faster than light by treating motion through space and time together, so everything moves at the speed of light through spacetime. It uses animated visuals to cover relativity basics in 12 minutes.

MIT Media Lab shows an imaging system capturing a trillion frames per second, fast enough to film light pulses travelling through objects in slow motion.

The Slow Mo Guys visit a lab with a camera capable of filming at 10 trillion frames per second, fast enough to see light travel. They show the setup and the resulting footage.

Half as Interesting explains why airlines flew empty 'ghost flights' out of Heathrow to keep their landing slots under use-it-or-lose-it rules.

JPL's David Cummings presents at the 2025 Flight Software Workshop how the team diagnosed and fixed the 2023 Voyager 1 anomaly from billions of miles away. It walks through the flight computer and the memory fix.

Captain Disillusion's VFXcool episode, led by Alan Melikdjanian, takes a 41-minute nostalgic look at how the visual effects of Flight of the Navigator were made. It covers early computers, motion control, in-camera effects and practical crafts.

A special lecture from MIT's Private Pilot Ground School in which Lt. Col. Randy Gordon, a fighter and test pilot, describes F-22 flight controls. Topics include thrust vectoring, the pilot command system and how software handles failures.

Douglas Hofstadter lectures at Uppsala University on how analogy and daring thinking drove Einstein's discovery of light quanta. He argues deep insight in physics comes from imaginative leaps rather than rigid logic.

A short screen recording of the flight simulator Easter egg hidden in Excel 97, with the steps to trigger it. The uploader notes the mouse controls are hard to handle.

The full webcast of SpaceX's Falcon 1 Flight 4, the first privately developed liquid-fueled rocket to reach orbit, on 28 September 2008. It includes the crew's cheering and Elon Musk's statement afterward.

A four-pane view of Armadillo Aerospace's Mod vehicle on a June 2010 boosted hop. The flight includes engine shutdown, drogue chute deployment, an engine restart and a safe landing.

A Ropecon 2019 talk by a lighting designer and a software engineer on how the Odysseus larp spaceship was built, using over ten IT systems, hundreds of lights and dozens of speakers. It covers the lessons learned.

A one-minute clip from Richard Feynman's 1979 Auckland lecture in which he answers whether you see an object or only its light. It is a short, playful take on perception and on the use of philosophy.

Mentour Pilot, a 737 captain, demonstrates in a full flight simulator why a Boeing 737 can become impossible to trim manually at high speed. He explains the jackscrew forces and the roller-coaster manoeuvre.

A BBC Earth clip from Super Powered Owls in which the team uses sensitive sound equipment to compare owl flight with other birds. It shows why owls fly almost silently.

Not Just Bikes explains how Dutch traffic lights use early detection, transit priority and conflict-free design to cut waiting. The aim is to move as many people as possible rather than as many cars.