mit opencourseware

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.

A short Harvard animation narrated by Professor Rob Lue introducing mitochondria as the cell's powerhouses and how cells turn food and oxygen into energy.

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

A short explainer on the physiological differences between fasting and simply eating less. It covers ketosis, ghrelin and hunger waves, and the hormonal effects of fasting.

Adam Ragusea explores why Hershey's chocolate tastes the way it does to many non-Americans, tracing it to butyric acid and Hershey's history, and why familiarity makes Americans love it. He compares it with British Cadbury.

The 8-Bit Guy explains the color limitations of 1980s computers and consoles such as the NES and Commodore 64. It shows how sprites, attributes and palettes shaped the look of old games.

Veritasium short showing Drew Berry's scientifically accurate animations of the molecular machines that drive cell division. It walks through mitosis, chromosomes and motor proteins.

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.

A short Harvard Online animation, narrated by Professor Rob Lue, showing how ATP synthase works inside mitochondria. It comes from the HarvardX Cell Biology: Mitochondria course.

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.

Real Engineering analyzes whether electric planes are feasible, focusing on battery energy density limits compared with jet fuel. It concludes electric flight works mainly for short ranges.

A video explaining why Japanese cities look the way they do, through Japan's national tiered zoning system that permits mixed use and flexible development. It compares this approach with more restrictive zoning elsewhere.

An Extra Credits episode on China's Sesame Credit, which gamifies obedient citizenship through a social score. It covers how the system rewards conformity and pressures people through their friends' behavior.

Wendover Productions explains why US passenger rail lags behind other countries. It covers freight companies owning most of the track, geography and population density, and the economics of competing with flying.

Kurzgesagt's animated take on climate change argues that, despite alarming headlines, there are real reasons for hope as technology, policy and public attitudes shift. It surveys trends and solutions while acknowledging the scale of the problem.

Tantacrul explains how he and engraver Simon Smith designed the free music notation font for MuseScore 3.6. It draws on the history of the SCORE notation application by Leland Smith.

Robert Miles asks whether corporations can be thought of as artificial general superintelligences and how far the analogy holds. He argues the differences, such as being limited by employees' capabilities, matter for AI safety.

Practical Engineering explains pumped storage hydropower, which makes up most grid-scale electricity storage. It covers how it works and why it fits only certain geographies.

Ben Felix explains how central bank money creation and quantitative easing actually work, and what they do and do not imply for asset prices and currency. He addresses the common belief that the Fed prints unlimited money and props up markets.

PBS Space Time explains Stephen Hawking's prediction of Hawking radiation and how black holes can emit radiation and slowly evaporate. It goes beyond the common particle-antiparticle analogy.

Engineering Explained examines new research suggesting corn ethanol in US gasoline may emit as much or more carbon than gasoline. It covers the Renewable Fuel Standard and why ethanol was assumed to be a green fuel.

Anders Puck Nielsen clears up common misunderstandings about what legally counts as genocide, then compares the situation in Gaza with the genocide case against Putin. The chapters cover the definition, individual intent, and the two case comparisons.

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.

The Plasticity creator explains what a geometry kernel is and compares commercial options C3D, ACIS, and Parasolid, describing his months of research and why he chose as he did.

Modern Vintage Gamer looks at OpenLara, an open source Tomb Raider engine, running on the Game Boy Advance. The video explains how the port achieves playable speeds on the GBA's slow ARM CPU, with input from the developer XProger.

A filmmaker explains why the Apollo moon landing footage could not have been faked in a studio, based on the video and film technology of the late 1960s. He walks through the limits of cameras, frame rates and effects of the era.

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.

Real Engineering explains the materials science behind metal 3D printing, including crystal structure, laser sintering, and why printed parts develop fatigue cracks. It shows how process imperfections limit the strength of printed metal.

A PBS Space Time episode on how gravitational wave observations of a neutron star merger, GW170817, can limit the number of spacetime dimensions. It is based on a 2018 paper.

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.

Kurzgesagt asks whether advanced civilizations could have existed on Earth in the deep past and left little evidence. It looks at time as a dimension for searching for alien civilizations and the limits of the geological record.

Dialect coach Erik Singer analyzes how accurate the accents are of 32 well-known actors, including Brad Pitt and Will Smith, in WIRED's breakdown.

Steve Mould explains motion amplification and video magnification, techniques that find tiny changes in video invisible to the eye and exaggerate them. He covers the MIT research and industrial uses such as diagnosing vibrating machinery.

An Extra Credits episode on how MMO economies get overrun by inflation when players can mint unlimited gold by killing monsters. It covers approaches borrowed from real-world economics, such as anchoring or pegging currency, as alternatives to simple gold sinks.

Steve Mould shows that LEDs and solar panels are both diodes made from semiconductors, so a solar panel can emit light and an LED can generate electricity. He demonstrates a small solar panel lighting up.

Scott Manley tells the story of a computerized telemetry system built to sit at the heart of a nuclear test device in place of the plutonium pit, designed to transmit data in the microseconds before it was destroyed.

PBS Space Time explains how general relativity permits warp drive in principle and covers recent theoretical advances toward solving the negative energy problem.

PBS Space Time asks whether dark matter could be made of primordial black holes. It walks through the observational constraints that limit this idea.