Physics

31 ideas, each explained on one page with a 60-second lesson you can play right there.

Anthropic principle The anthropic principle explains that we observe physical constants suitable for life because observers cannot exist in a universe without them.
Atomic Clock Atomic clocks measure time using resonant atomic frequencies, defining the SI second as 9,192,631,770 oscillations of a caesium-133 atom.
Block Universe The block universe theory treats time as a fourth dimension where past, present, and future events are all equally real and fixed.
Blue Blue is light with wavelengths between 450 and 495 nanometers.
Copernican Principle The Copernican principle states that Earth occupies an average position in space and that humans are not privileged observers of the universe.
Determinism Determinism is the philosophical view that every event is the inevitable result of preceding events and the laws of nature.
Doppler Effect The Doppler effect changes the observed pitch or frequency of waves when a source and observer move relative to each other.
Doppler Effect of Light The Doppler effect of light shifts the wavelength and frequency of electromagnetic waves when a light source and observer move relative to each other.
Double-Slit Experiment How the double-slit experiment proved wave-particle duality by showing light and matter act as waves until they are measured.
Drake Equation The Drake equation is a mathematical formula that estimates how many active, communicative alien civilizations exist in our galaxy.
Entropy Entropy is a measure of how widely energy in a system spreads out and becomes unavailable to do useful work.
Fermi Paradox The Fermi paradox exposes the clash between the high statistical odds of alien life across billions of stars and our complete lack of evidence for it.
General Relativity General relativity explains gravity as the warping of space and time by mass and energy, replacing Newton's concept of an attractive force.
Gravitational time dilation Gravitational time dilation is the actual difference in how fast time passes for objects at different distances from a heavy mass.
Heisenberg's Uncertainty Principle Heisenberg's Uncertainty Principle sets a fundamental limit on how precisely you can measure a particle's position and momentum at the same time.
Jet Propulsion Jet propulsion pushes objects forward by shooting out fluid in the opposite direction, powering aircraft, rockets, and swimming squid.
Joint Cavitation Joint cavitation is the formation of gas bubbles inside the lubricating fluid of a joint when its surfaces are pulled apart.
Laplace's Demon Laplace's Demon is a thought experiment about a hypothetical intellect that knows the exact position and motion of every particle in existence.
Oceanography Oceanography is the scientific study of the ocean, exploring its physics, chemistry, biology, geology, and global currents.
Quantum Computer A quantum computer is a device that processes information using quantum states rather than classical binary switches.
Quantum Entanglement Entangled particles share one quantum state, so their measurements stay correlated across any distance in ways local hidden variables can't explain.
Quantum Superposition Quantum superposition is the principle where a physical system exists in multiple possible states simultaneously until it is measured.
Quantum Tunneling Quantum tunneling is a physical process where a particle passes directly through an energy barrier it lacks the energy to climb over.
Rhythm Rhythm is the regular flow of movement or sound created by alternating strong, accented elements with weaker ones.
Schrödinger's Cat Schrödinger's cat is a thought experiment showing the paradox of quantum superposition, where a cat in a sealed box is both alive and dead.
Sonic Boom A sonic boom is a loud sound resembling an explosion caused by shock waves when an object moves faster than the speed of sound.
Space Exploration Space exploration is the physical investigation of outer space using uncrewed robotic probes and human spaceflight.
Special Theory of Relativity The Special Theory of Relativity is a physics theory describing the relationship between space and time for objects moving at constant speeds.
Speed of Light The speed of light is the universal speed at which electromagnetic waves and massless particles travel through a vacuum, which is empty space.
Time Dilation Time dilation is the difference in elapsed time measured by two clocks due to relative speed or gravity.
Wave-Particle Duality Wave-particle duality shows that fundamental objects like electrons and photons behave as waves or particles depending on how they are measured.