four chords

3Blue1Brown's animated visual introduction to the Fourier Transform, showing how a signal breaks into frequency components.

Huygens Optics explains the Fourier transform and shows how a lens performs one optically. A DLP projector is used as a Fourier filter to do simple pattern recognition on lithographic character patterns.

3Blue1Brown introduces Fourier series, from the heat equation to drawing arbitrary shapes with rotating circles. It builds a visual intuition for decomposing functions into sine waves.

A comedy-music medley from the Australian band The Axis of Awesome showing that dozens of famous pop songs use the same four-chord progression. The performers cycle through a long list of hits over the same chords.

Australian comedy group Axis of Awesome perform a sketch showing that dozens of pop hits share the same four chords. It was recorded at the 2009 Melbourne International Comedy Festival.

Mathologer explains epicycles and complex Fourier series, inspired by an animation of Homer Simpson drawn with epicycles. It covers the shape of the Moon's orbit around the Sun and how to make your own epicycle drawings.

3Blue1Brown shows how the uncertainty principle arises from Fourier transforms. A wave packet cannot be narrow in both position and frequency, so the principle is a property of waves rather than of measurement.

Reducible's visual walkthrough of the Fast Fourier Transform, motivated by polynomial multiplication. It shows how the FFT's key ideas can be discovered by asking the right questions.

The first of four short videos from Bill Hammack (engineerguy) introducing and giving the history of a 100-year-old mechanical computer, Michelson's harmonic analyzer. The series goes on to explain Fourier synthesis, analysis and operation of the machine.

Matt Parker gives a hands-on Royal Institution talk on how four-dimensional shapes appear in a 3D world, with props like straw frames, Mobius strips and a knitted hat. It is a playful general-audience tour of the fourth dimension.

Veritasium tells the story of the Fast Fourier Transform, from its use in detecting nuclear tests to Cold War politics, and how it could have changed the arms race. It includes a short, intuitive explanation of what the Fourier transform does.

The classic Monty Python sketch in which four Yorkshiremen compete to claim the hardest upbringing, each story more absurd than the last.

A short animation reconstructing a planet's looping orbit using Ptolemy's epicycles and deferents, with the epicycles tracing out the face of Homer Simpson. It shows how enough circles can reproduce nearly any shape.

Database pioneer Michael Stonebraker argues that 'big data' is really at least four different problems: big volumes with small analytics, big analytics, velocity, and variety. He comments on where each market is heading.

The full 1984 interview with Yuri Bezmenov, a former KGB operative, in which he lays out four stages of ideological subversion. It is a long interview with G. Edward Griffin.

Guy Steele presents a small geometric problem and compares four computational approaches: a classic sequential solution and three parallel-friendly ones. Each is illustrated pictorially and with working code, weighing total work against time to solution.

A segment from Carl Sagan's original Cosmos explaining the fourth spatial dimension through analogy with a two-dimensional world and shadow projection.

Scott Wlaschin's NDC Oslo talk on four 1970s languages, SQL, Prolog, ML and Smalltalk. It explains their philosophies and what practical principles they still offer modern developers.

An Intelligence Squared debate in which Will Self argues for Brave New World and Adam Gopnik for Nineteen Eighty-Four as the better dystopian warning. It includes acted excerpts and is chaired by Jonathan Freedland.

A Clojure/conj 2014 talk by Lucas Cavalcanti and Edward Wible on four uses of Datomic. They cover HTTP caching, audit trails, mobile database sync and authorization, drawing on the immutable transaction log.

The Monty Python sketch in which four wealthy Yorkshiremen try to outdo each other with exaggerated tales of childhood poverty.

The classic Monty Python Four Yorkshiremen sketch from Live at the Hollywood Bowl, in which four men try to outdo each other with exaggerated tales of childhood hardship.

A short explainer showing what walking through walls would look like with movement in a fourth spatial dimension, using the 4D puzzle game Miegakure.

A classic 1967 comedy sketch from At Last the 1948 Show, with Tim Brooke-Taylor, John Cleese, Graham Chapman and Marty Feldman as four prosperous Yorkshiremen trying to outdo each other with exaggerated tales of childhood poverty. It is the precursor to the version later performed by Monty Python.

Andrew Huang teaches the basics of music theory in about half an hour, covering intervals, chords and patterns. He stresses understanding how music works over memorizing terminology.

An independent feature documentary in which 23 economists, advisers and financiers discuss how the financial system works and what a more just economic model might look like. It covers money creation, debt and the aftermath of the financial crisis.

A short video advising how to handle a police stop by politely refusing searches and not answering questions, citing Fourth and Fifth Amendment rights.

A 3Blue1Brown live lockdown math episode asking what Euler's formula e^(pi i) is actually saying. It builds intuition through exponentials, rotation and vectors landing on the unit circle.

CGP Grey argues that the two-day weekend is poorly structured and proposes taking days off midweek, such as Wednesday and Sunday, instead.

Scott Galloway's DLD15 talk assessing the competitive positions of Amazon, Apple, Facebook and Google. He argues about where each is strong and weak, including Amazon's need for physical retail.

A Capella Science parody of Despacito that sings through evolutionary developmental biology, explaining how a single cell becomes a body, including body-axis genes and dormant snake leg DNA. It runs about four minutes.

Alex Martelli's Google Developers Day talk on classic design patterns (creational, structural and behavioral) and how they appear in Python. He stresses that patterns must be studied in the context of the implementing language.

A driver films a police DUI checkpoint on the 4th of July where a drug dog alerts on his car and he is searched without consent, though he broke no laws. He is released without charges after officers learn he was recording.

Hans Rosling uses augmented-reality animation to show 200 countries over 200 years in four minutes, built from 120,000 data points. It tracks life expectancy and income to show the world's development.

A four-minute Not Just Bikes comparison of grocery shopping in Amsterdam versus car-centric North America, arguing that frequent small fresh-food trips beat bulk shopping. It ties this to land use and reduced food waste.

Hans Rosling and his son Ola run an audience quiz with global population, health and income data to show how wrong most people are about the world. Ola then gives four ways to get less ignorant.

Lex Fridman interviews Navy pilot David Fravor, a primary witness of the 2004 Tic Tac UFO encounter, about the sighting, military aviation and aerospace engineering. The conversation runs close to four hours.

3Blue1Brown builds visual intuition for quaternions, showing how to think about this four-dimensional number system using stereographic projection and rotations in 3D space. It is part one of a two-part series with an interactive companion site.

Brian Will follows up his earlier anti-OOP video by walking through four short code examples, including Java code in the style of Uncle Bob, to show how object-oriented design complicates simple programs. It argues that OOP hides and scatters state and adds needless indirection.

The first part of Dmitry Vasyukov's four-part Russian documentary series about trappers and villagers living in the Siberian taiga. This episode follows spring life along the Yenisei, with hunting, fishing and subsistence in harsh surroundings.