Notes for anyone who wants to understand physics from the ground up — from Newton's laws to the Schrödinger equation. Not a dry textbook: live animations, worked numerical examples, and experiments you can actually try at home. Every note links to the site's own law and scientist cards — click an unfamiliar term.
In 1820, Hans Ørsted accidentally noticed that a current-carrying wire deflects a compass needle — and within a week, André-Marie Ampère built a quantitative law from this. Eleven years later,…
Daniel Bernoulli derived the energy conservation equation for flowing fluid in 1738: along a streamline, the sum of pressure, kinetic, and potential 'energy per unit volume' remains constant. A…
Any body emits thermal radiation, and the shape of this glow depends only on temperature — not on the material (for an ideal 'black body'). Wien's law (1893) gives the color of the radiation peak,…
From Newton's three laws (see part I) follow three quantities that in a closed system do not change over time: momentum, energy, and angular momentum. These are not random coincidences but a direct…
In 1785, Charles Coulomb measured how electric force decreases with distance — exactly like gravity (inverse square law, part VII). Forty-one years later, Georg Ohm discovered another, equally simple…
In 1842, Christian Doppler predicted: the frequency of a wave you hear or see depends on how the source moves relative to you. A source flying toward you 'squeezes' the waves in front of it — you…
In the 1660s, Robert Hooke discovered that springs (and elastic bodies in general) resist deformation proportionally to its magnitude — the simplest linear relation underlying elasticity theory, from…
In 1748, Leonhard Euler, expanding excos x and sin x into infinite series and substituting an imaginary number for x, discovered that all three functions are actually different projections of the…
Johannes Kepler, analyzing Tycho Brahe's observations, derived three empirical rules of planetary motion—long before Newton explained where they come from. It turned out that all three of Kepler's…
In 1834, Émile Clapeyron combined three independent experimental laws (Boyle, Charles, Gay-Lussac) into a single equation of state for an ideal gas. Behind the simple formula pV = nRT lies an honest…
In parts I and II of this series, we already twice encountered a hint of a deeper level: both with Newton and with conservation laws, there was a §6-teaser about the principle of least action and…
In the 1860s, James Clerk Maxwell gathered the disparate experimental laws of Coulomb, Gauss, Ampère, and Faraday into a system of four equations—and discovered a missing piece: without it, the…
Newton's three laws (1687, "Mathematical Principles of Natural Philosophy") are a minimal set of axioms from which all classical mechanics is derived: why a body with no net force moves uniformly in…
In 1926, Erwin Schrödinger, developing Louis de Broglie's idea of the wave nature of matter (see Euler's formula, part V), derived an equation determining the evolution of the wave function ψ — a…
In Part X we already encountered the 'lifeguard on the beach' problem — a hint at how light chooses the path of least time. Here we provide a full breakdown of two laws governing wave reflection and…
Thermodynamics is a rare branch of physics with a "law number zero": the basic principle explaining temperature itself was realized later than the first and second laws and was numbered…
The experimental setup spins a wheel in the vertical plane and records readings from an accelerometer fixed on the rim — i.e., in a non-inertial, rotating reference frame. This note provides a…