start with why

Practical Engineering explains what a black start is: restarting a power grid after total collapse. It shows why most plants need outside power to start and why rebuilding a synchronized grid is delicate and high-stakes.

Tim Dodd's hour-long deep dive on how rocket engines start, from solid motors to liquid engines. It covers thermal conditioning, spin-up, ignition methods, starting in space, and a step-by-step RS-25 startup.

Matt Parker of Stand-up Maths explains why people keep making the same mistake with millions and billions, using a Bloomberg cash calculator example. He looks at the unit slip behind the repeated arithmetic error.

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.

Chef Jon Kung explains why he cooks almost exclusively on induction, citing fast heating, cleanliness and precise temperature control. He shows a rounded induction wok burner.

Wendover Productions explains why American towns, retail and buildings increasingly look alike, covering zoning pressures, corporate standardization and cheap construction types like 5-over-1 buildings.

All Cars with Jon explains how EPA fuel economy rules, especially the footprint-based CAFE formula, push automakers away from small trucks.

Robert Miles explains instrumental convergence: why an AGI with almost any goal would tend to pursue sub-goals like self-preservation and resource acquisition. It builds on Omohundro's basic AI drives and his orthogonality thesis video.

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.

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.

A minutephysics video explaining why a piano cannot be perfectly tuned, comparing equal temperament with just intonation and the math of harmonics.

Scott Manley examines why SpaceX, Google and others are looking at orbital data centers. He walks through the economics, heat rejection and solar power arguments, with links to the Lumen/Starcloud and Google Suncatcher papers.

minutephysics, in collaboration with the US Census Bureau, explains differential privacy and why the 2020 census adds noise to protect individuals' data. It walks through how statistics can leak private information.

Dr. K of HealthyGamerGG explains why people feel unmotivated and unable to start tasks after hours of YouTube or similar distractions. He frames it as a result of how social media is designed to capture attention, and says not to blame yourself.

A short Techquickie explainer on why laptop webcams are much worse than phone cameras. It covers sensor size, image processing, and the interface differences between laptops and phones, with input from a Logitech engineer.

RealLifeLore explains France's military posture towards Russia, including French involvement in Africa and Russian influence in the Sahel. It covers the geopolitics behind current tensions.

Ben Felix examines whether the well-known 4% retirement withdrawal rule holds up, drawing on academic papers. He argues that a safe rate may be closer to 2.7%, especially for early retirees.

Tom Scott explains for Computerphile why handling time and timezones in code is so hard, walking through a simple web app that computes how long ago something happened. It covers the quirks of timezones and calendars and ends in an exasperated rant.

An animated 44-minute summary of Ray Dalio's book Principles for Dealing with the Changing World Order. It lays out the Big Cycle of rising and declining nations, covering debt cycles, internal conflict, and shifts in global power over the past 500 years.

CGP Grey explains first-past-the-post voting and why it pushes elections toward two dominant parties. It is the first in his series on electoral systems.

Veritasium examines the role of luck in success, with simulations and examples showing how small advantages and chance can compound. It argues that top outcomes are disproportionately luck-driven while still crediting effort.

Technology Connections explains why heat pumps matter right now, covering their efficiency, how they hold up in cold weather and the energy savings over burning fuel. It follows his earlier explainer on how they work.

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.

Tom Scott explains for Computerphile why electronic voting is a bad idea, arguing that paper ballots are transparent, auditable and hard to tamper with at scale. He covers why moving voting to phones, tablets or computers undermines trust and verifiability.

CGP Grey explains how ideas spread like germs, and why content that triggers outrage spreads fastest, using a study on what makes online content viral. He argues that opposing outrage-driven memes feed each other.

Technology Connections' long closing video in his heat pump series, arguing that adopting heat pumps is well within reach. It explains how they work and what it takes to start using them.

Technology Connections explains why electric kettles are uncommon in the US, centering on 120V circuits limiting power. He tests ways of boiling water on gas, electric ranges and kettles.

RealLifeLore explains with maps why Russia invaded Ukraine, focusing on energy resources, security buffers, Black Sea access and Crimea's strategic value.

Numberphile's Ben Sparks shows why the golden ratio is the most irrational number, using seeds, continued fractions and rational approximations. He also explains why plants use it for spacing leaves and seeds.

Technology Connections explains why single-hose portable air conditioners are inefficient and often a poor choice compared with window units. It details how the single hose pulls in warm outside air and wastes energy.

Real Engineering looks at why Africa's abundant solar potential is hard to turn into usable power, especially for Europe. It covers the transmission, infrastructure and economic obstacles, and the pivot from concentrated solar to photovoltaics.

Adam Neely explains what perfect (absolute) pitch is, how it differs from relative and quasi-absolute pitch, and why he would not want it. He covers its drawbacks, including drift with age.

Not Just Bikes explains why cars rarely crash into buildings in the Netherlands, attributing it to street design that forgives mistakes and to systematic crash investigation. It contrasts this with North American acceptance of such crashes.

A Wendover Productions explainer on why train tickets, especially Amtrak in the US, cost so much compared with flying. It breaks down staffing, speed and the cost components behind a ticket.

The Map Men explain why British place names are so hard to pronounce, tracing it to layers of Viking, Anglo-Saxon, Celtic and Norman influence, with a pronunciation guide.

A short animated TED-Ed lesson in which two competing ice cream vendors on a beach illustrate why rival shops cluster together. It introduces game theory and the Nash equilibrium through the Hotelling model.

Wendover Productions explains why modern airliners fly no faster than they did decades ago, covering the economics of speed and fuel efficiency, and why supersonic travel faded.

Tom Scott explains why confetti and snow wreck video quality, using interframe compression and bitrate. He demonstrates it live by changing the quality on screen.

A minutephysics explainer on why the planets orbit in a flat plane. It shows how conserved angular momentum flattens a collapsing cloud of matter into a disk.

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.