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A Computerphile video in which Mark Jago of the University of Nottingham explains Turing's halting problem and how it led to the blueprint for the modern computer.

Astrophysicist David Kipping presents the halo drive, a proposed way to propel a starship to a good fraction of light speed by gaining energy from a black hole. The video is based on his peer-reviewed paper and explains why energy is the main obstacle to interstellar flight.

Geoff Marshall explains a running gag about London Underground stair signs claiming that the climb equals 15 floors, regardless of how many steps there actually are.

A Kurzgesagt animation walking through how a Mars base could be built and why it would be punishing, covering radiation, temperature extremes, toxic dust and the need for shielding.

A PBS Space Time episode explaining why faster-than-light travel is equivalent to travelling back in time, using relativity and Minkowski diagrams for different observers.

A short, sarcastic Half as Interesting video about a tiny freight railway in Canada built to exploit a shipping regulation loophole. It explains how a track just 100 feet long counted as a railway.

A Half as Interesting explainer on the US program that drops millions of sterile screwworm flies over Panama every week to keep the parasite out of North America.

Half as Interesting explains why the Eiffel Tower's night-time lighting is under copyright, which makes publishing photos of it at night legally problematic.

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.

Practical Engineering explains why connecting solar and other inverter-based generation to the grid is hard. It covers grid stability, load balancing and the behind-the-scenes engineering challenges of renewables.

A CAD-based animation from the Max Planck Institute for Plasma Physics showing how the Wendelstein 7-X stellarator is configured and what its fusion research aims to achieve. It runs about 11 minutes.

A SciShow episode in which Hank Green introduces five of the most dangerous chemicals, from lethal toxins to substances that explode on contact. It is an entertaining overview of extreme chemical hazards.

David Spiegelhalter, Professor of the Public Understanding of Risk, uses statistics to weigh everyday risks such as bacon sandwiches and cycling. The six-minute piece introduces micromorts as a way to compare the risk of dying.

Asianometry explains why Russia cannot replace TSMC after sanctions halted chip shipments. It looks at Russian chip designers such as Baikal, MCST and Yadro, and at Russia's lagging domestic manufacturing capacity.

A Vox explainer on why California's high-speed rail project is years late and far over budget, with only a few concrete structures built by 2022. It covers the political, legal and routing challenges behind the delays.

Tom Scott explains Electrical Network Frequency analysis, where hum from the power grid in a recording is matched against grid logs to date and place it. He talks to a researcher and sets them a challenge.

Insider explains how The Mandalorian replaced green screens with LED walls that project real-time 3D environments behind actors, with over half the show filmed on such virtual sets.

Professor Brailsford of the University of Nottingham describes how the university set out to print its own mathematics exam papers in the 1980s. The story centers on getting a Mergenthaler Linotron 202 typesetter to work with their own software.

Nature video showing MIT researchers flying the first plane with no moving parts, powered by an ion drive that creates an ionic wind from high-powered electrodes. The 5m-wide craft flies across a sports hall.