limits of knowledge

WIRED has UCLA professor Amit Sahai explain zero-knowledge proofs to a child, a teen, a college student, a grad student and an expert. Each round goes deeper into the cryptography and why it matters.

Kurzgesagt explains why, even with science-fiction technology, most of the universe is permanently out of reach because of cosmic expansion and finite resources.

An animated 11-minute tour of the whole field of mathematics as a single map, showing how pure and applied math and their sub-fields relate to each other.

Not Just Bikes explains how North American speed limits are set and why posted limits matter far less than street design. It argues that drivers follow the road's cues, so safe speeds have to be built into the street.

Technology Connections explains how the simple American drip coffee maker works, including the bimetal valve and bubble-pump heating, and compares the original Mr. Coffee with modern machines.

A cardiologist runs a detailed, skeptical review of the Wim Hof Method, covering the research on cold exposure and breathing techniques. It also teaches how to read scientific statistics critically.

PBS Space Time, together with It's Okay to be Smart and PBS Eons, asks how a universe drifting toward disorder produced something as complex as life. It presents the idea that the laws of physics, through thermodynamics, may actually favor the emergence of life.

Asianometry examines why Japan's software industry has lagged despite its hardware strengths. It looks at dependence on US software and the low prestige of programming.

Real Engineering explains why biofuels, especially corn ethanol, are a poor energy source, looking at energy inputs, efficiency and carbon cost.

An RSA Animate video that illustrates a talk by geographer David Harvey on the crises of capitalism. It covers creative destruction, wage stagnation masked by credit, and the search for a more just economic order.

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.

James Hoffmann explains how decaf coffee is made, how the decaffeination processes differ, and why decaf is roasted and stales differently. He also discusses decaf quality and health questions.

James Hoffmann runs caffeine analyzer tests comparing filter versus espresso, extraction over time, steep time, instant coffee and light versus dark roast.

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.

Wendover Productions examines why carbon offsets so often fail to reduce emissions, covering specific examples and the perverse incentives in offset schemes.

An Adam Ruins Everything segment on the real facts of the McDonald's hot coffee lawsuit, covering the severity of the burns and the corporate PR campaign that painted it as frivolous.

Astronomer David Kipping of Cool Worlds talks with Mick West to break down the three declassified Pentagon UFO videos. They explain the footage through camera artifacts, glare, and perspective effects.

Alex O'Connor shows that ChatGPT cannot draw a wine glass filled to the brim, and ties the failure to David Hume's missing shade of blue. It asks what the failure says about how image models learn.

Marcus du Sautoy of the BBC demonstrates the wisdom of the crowd, showing that averaging many guesses of jelly beans in a jar lands near the true count.

Vsauce asks whether music will ever run out of new melodies. It counts the possible note combinations and discusses how common chord progressions and remixing affect originality.

A re-upload of a video breaking down Eminem's rhyme schemes, showing multi-syllable and internal rhymes in songs such as Lose Yourself. It aims to show why he is considered a standout lyricist.

CGP Grey explains that the City of London is a tiny, separate entity with its own governance, history and privileges, distinct from the city called London. He covers its financial role and how it is run.

CGP Grey explains the City of London's unusual governance, including the Lord Mayor, guilds, and how it differs from the rest of London.

A short How to ADHD explainer, featuring Brendan Mahan, on why simple tasks can feel impossible for people with ADHD. It introduces the 'wall of awful', a pile of past failures, shame and anxiety that builds up in front of a task and blocks starting it.

Veritasium traces analog computers from the Antikythera mechanism and Kelvin's tide-predicting machines to fire control and modern analog approaches. It explains how these machines computed continuously rather than digitally.

An Isaac Arthur episode on civilizations in the far future, past the Black Hole Era. It covers iron stars, Boltzmann brains, reversible computing and the idea of reversing entropy.

David and Ben Crystal introduce the Original Pronunciation production of Shakespeare and show what it reveals about the history of English, including puns and rhymes lost in modern speech.

A Veritasium video that follows the principle of least action from Bernoulli and Newton to quantum mechanics, asking whether light takes all possible paths at once. It includes experiments showing quantum waves.

CGP Grey's short explainer arguing that caffeine addiction is mostly harmless and may even be beneficial. It covers what caffeine does in the body.

Vsauce explores how human reasoning works, drawing on the social theory of reason and the extended mind thesis, made in partnership with Bill Gates around climate change.

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.

A two-minute clip in which Milton Friedman uses a humble pencil to show how thousands of strangers across many countries cooperate, without central direction, to make a simple product. It is a short visual version of the 'I, Pencil' essay's argument about free markets and dispersed knowledge.

The School of Life sets out principles for making attractive cities, arguing that the art has been lost in the modern world.

NASA's animated explanation of the Curiosity rover's Mars landing, which relied on a complex automated sequence taking about seven minutes. It features NASA engineers discussing the risks before the 2012 landing.

An RSA Animate drawing of Barbara Ehrenreich's talk on the darker side of positive thinking. It argues that forced positivity in culture, work and policy can be harmful and played a part in the financial crisis.

An RSA Animate illustrating a lecture by psychologist Philip Zimbardo on how people's perspectives on time (past, present, future) shape work, health and well-being.

A School of Life video arguing that everyone marries someone who is somewhat wrong for them, and that this is unavoidable. It is a four-minute version of an essay by Alain de Botton.

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.

Freya Holmer's 74-minute video essay on splines, covering Bezier curves, B-splines, derivatives and the different levels of continuity (C0, C1, C2), built with custom animation tools. She notes she did not cover non-uniform splines.

Asianometry explains the EUV light source inside ASML's lithography machines, where lasers hit falling tin droplets twice to produce 13.5 nm light. It walks through the engineering of the droplet generator, the pre-pulse and main laser, and the plasma that results.