optics

Applied Science shows how telecentric and hypercentric optics differ from normal lenses, producing no or negative perspective. The video builds a telecentric system from a Fresnel lens and demonstrates a lens that can see around objects.

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.

Huygens Optics shows how DIY photon sieves shape a laser's wave front, explaining how they differ from zone plates and how aperture count affects the focal point, with time-resolved visualizations of the diffraction.

Huygens Optics shows through a laser interference experiment that the question of a photon's size is really about coherence length. It argues that photons exist as energy exchanges between radiation and matter, not as little particles in free space.

Huygens Optics explores the idea that space is a non-linear elastic medium, and uses simulations to show how wave energy might be confined locally into particle-like objects. It touches on inertia, the Schwinger limit and the vacuum as a medium.

Technology Connections explains why brown is not a spectral color but a context-dependent perception, essentially dark orange seen against brighter surroundings.

3Blue1Brown visualizes Feynman's lecture on the refractive index, explaining why light appears to slow down in glass and why the effect depends on color. It builds the idea from waves produced by oscillating charges in the material.

Richard Feynman, in a clip from the BBC series Fun to Imagine, takes on the puzzle of why mirrors seem to swap left and right but not top and bottom.

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.

Veritasium visits the US Navy's Crane facility to test top night vision goggles. It explains how image intensifier tubes and thermal or digital systems work and compares the generations of the technology.

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.

Veritasium revisits Thomas Young's original double slit experiment with light, showing how interference supports the wave nature of light. It uses a pond-wave demonstration to explain the pattern.

Huygens Optics experiments with etching tiny patterns in glass, covering hydrofluoric acid risks, buffered oxide etch, photoresist and chromium masks, and laser-induced etching. It ends with attempts at microscopic Tesla valves.

DIY Perks builds a realistic artificial sun for dark winters, using a powerful water-cooled LED, a satellite dish reflector for near-parallel rays, and a scattering layer to mimic the blue sky. The video explains the optics behind why most lamps do not look like sunlight and shows the build and its results.

A Bell Labs film in which Dr. J.N. Shive uses a mechanical wave machine to demonstrate reflection, standing waves, resonance and impedance matching. He includes some equations but relies mostly on real-world examples a layperson can follow.

Technology Connections explains how heat pumps work as reversed air conditioners and why they can deliver several times the heat of resistive heating per unit of energy. It also tackles common myths such as poor cold-weather performance.

A short clip from a Richard Feynman interview in which he explains fire, describing how burning wood releases sunlight stored by the tree, which built itself mostly from air. It showcases his curiosity and plain-spoken explanations.

Veritasium argues that electric energy is carried by fields around the wires rather than by electrons moving through them, using a thought experiment with a large circuit.

Technology Connections explains how old-fashioned non-electronic rice cookers work, using a magnet and spring switch tripped by the Curie point. It shows the thermodynamics and magnetism behind a simple appliance.

AlphaPhoenix uses a custom high-speed measurement setup to watch voltage waves travel down wires and split at a fork. It answers how electricity knows where to go and how quickly that process happens.

A short video from the trafficwaves.org site showing how traffic jams and standing waves form, including the fight between cheaters and blockers at an exit-lane backup. It also touches on how individual driving behavior affects the flow.

Destin Sandlin of Smarter Every Day undergoes hypoxia training and experiences his own impaired thinking as oxygen is withdrawn. The video shows how quickly and unnoticeably oxygen deprivation degrades judgment, illustrating why you put your own mask on first.

Veritasium explains how trees lift water from roots to the top of tall trunks, using transpiration pull and the negative pressure that liquid water can sustain. It explains why trees do not need pumps or valves.

A Smarter Every Day episode from aboard a nuclear submarine on how the crew makes breathable air. It covers oxygen generation from seawater, oxygen candles and CO2 scrubbing with amine.

A PBS clip in which Richard Feynman explains the strange nature of light and electromagnetic radiation. He conveys how little of it we actually see and how radio waves are present everywhere.

Bill Hammack of engineerguy introduces his series on Michael Faraday's lectures on The Chemical History of a Candle. He describes the free companion book and the commentary and caption features that help modern viewers.

CuriousMarc powers up a vintage HP 5061A cesium beam clock and explains both the quantum principle and the HP implementation in detail. It is part of a longer atomic clock series.

Matthias Wandel uses anemometer measurements to find where to place a fan to move the most air through a house at night. He finds that placing the fan some distance back from the window works better.

Veritasium explains why bicycles are stable, arguing that gyroscopic effects are not the answer. The video shows countersteering and an experiment where riders blocked from steering the opposite way cannot turn.

Veritasium's Derek Muller visits NASA JPL to see the Mars helicopter Ingenuity before it was mounted on the rover. He explains how it can fly in Mars's thin atmosphere with large, fast-spinning contra-rotating rotors and low mass, and covers power and cold.

Benn Jordan investigates infrasound and low-frequency noise from data centers, including xAI's Colossus and a crypto mine, and reports his own experiments on the effects. The video covers the health and community impacts on nearby residents.

Smarter Every Day films Prince Rupert's drops, tempered glass drops, in high-speed slow motion at 130,000 fps. It shows how the drop's heavy internal stress lets the head survive hits while the tail shatters the whole thing.

A minutephysics explainer showing that the Moon's path around the Sun is not a spiral but closer to a 12-sided polygon with curved corners. It argues the Moon arguably orbits the Sun rather than the Earth.

Veritasium shows silicone oil droplets bouncing on a vibrating bath, a physical analogue of pilot wave theory that reproduces quantum-like behavior such as double-slit patterns.

A short demo of a walking droplet on a vibrating silicone oil bath passing through a double slit and producing interference, a macro-scale analogue of pilot-wave behavior.

Destin Sandlin of Smarter Every Day explains Multi-Domain Operations through footage from his last mission at RIMPAC 2018. He covers missile and torpedo testing and interviews military leaders about the cyber and information domains.

OK Go's music video for Upside Down & Inside Out, filmed during parabolic flights so the band and performers are weightless in the plane.

Destin of Smarter Every Day learns to ride a bicycle whose steering is reversed, taking about eight months, and compares it with how his young son learned much faster. It illustrates knowledge versus understanding and brain plasticity in adults versus children.

Veritasium asks people where a tree's mass comes from, then explains that most of a dry tree's mass originates from carbon dioxide in the air. It combines street interviews with a short explanation of photosynthesis.

Veritasium explores compliant mechanisms, devices that move by flexing rather than using hinges and joints, with researchers at BYU. It covers advantages such as fewer parts and precision, including uses in nuclear weapon safety.