light pen

David Heinemeier Hansson's opening keynote at RailsConf 2019 argues against the expectation of payment for open source work, drawing on his experience releasing Rails. It also includes lighter asides about the industry.

PBS Space Time explains what happens as you approach and cross a black hole's event horizon, using Penrose diagrams and light cones as the tool for understanding spacetime there.

Bobby McFerrin uses audience participation at a World Science Festival event to demonstrate how instinctively people follow the pentatonic scale.

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.

Evan Czaplicki, creator of Elm, discusses the hard parts of running an open source project: online community conflict, why its patterns arise, and a cultural history of open source. He offers ideas for more civil, productive communication.

Deviant Ollam, head of a physical penetration testing team, presents tactics for getting into buildings, from bypassing door levers with a wire to defeating bank doors. He argues that physical security is often surprisingly weak.

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.

A beginner-focused tutorial on freehand knife sharpening with a single stone, aiming for a shaving-sharp edge in about five minutes.

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.

CGP Grey's short animated argument for abolishing the US penny, covering its cost and history.

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.

Bryan Cantrill's talk on corporate open source anti-patterns, first given at FISL 2012 and again at the Liferay Symposium. He lays out the mistakes companies make when open sourcing code, such as announcing future open sourcing, and discusses licenses.

A dotJS 2012 conference talk by Fat (of Twitter Bootstrap fame) on what open source really means and why maintainers feel guilty about it. It covers the obligations, expectations and burnout that come with releasing popular open source software, delivered with humor.

David Christiansen gives a Strange Loop 2018 introduction to dependent types, where one language serves for both compile-time and run-time code and programs unite with proofs. It draws on his book The Little Typer.

Bryan Cantrill's OSCON 2015 talk on moving a proprietary product to open source, drawing on Sun's history with Solaris and illumos, licensing choices and the relicensing after Oracle's acquisition.

Tim Ansell presents the SkyWater PDK, a fully open source manufacturable process development kit for a 130nm process, as the first FOSSi Dial-Up talk. He covers its role in a fully open chip design flow.

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 short CNET demo of Bose's electromagnetic active suspension, which gave a very smooth ride but never reached the market. It shows the system in action.

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.

A short hyperlapse of a 2019 Toyota Corolla using comma.ai's OpenPilot 0.6.3 to drive 100 miles with no intervention except for the windshield wipers.

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.

A short film from the Competitive Enterprise Institute adapting Leonard Read's 1958 essay I, Pencil, showing how no one person knows how to make a pencil and how many people cooperate without central planning.

Urs Hoelzle, Google's SVP of infrastructure, gives the 2012 Open Networking Summit keynote on how Google adopted OpenFlow and software-defined networking in its own networks. The slides are linked in the description.

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.

Okta developer advocate Nate Barbettini explains OAuth 2.0 and OpenID Connect in a roughly hour-long talk. It starts from the problems the protocols solve and walks through the flows. The description notes the implicit flow material is now out of date.

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.

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.

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.

Inventor Mary Lou Jepsen demonstrates using red light and sound to see inside the body and brain, aiming at tumor detection and neural activity measurement, and potentially a cheaper wearable MRI replacement.

A TU Vienna demo of a double inverted pendulum on a cart, using constrained feedforward and optimal feedback control for swing-up and point-to-point motion.

A short Global News report on the Pentagon confirming a $22 million UFO investigation program and releasing Navy infrared footage from the 2004 Nimitz encounter.