Forces / History
The history of physics
Every formula in the labs above was, at some point, somebody's wild new idea — usually one that overturned what everyone already "knew." This is that story, start to finish: 25 scientists and experiments from 350 BCE to 1947, each with a small animated re-creation and, where it fits, a link straight into the Forces lab that covers what they discovered.
Ancient & early ideas — before 1600
Two thousand years of careful reasoning, with almost no experiments to check it against.
Aristotle
Taught that heavier objects fall faster than lighter ones — a claim that felt obviously true and went essentially unchallenged for almost two thousand years. It's wrong, but it's the idea Galileo would eventually have to overturn.
Archimedes
Worked out the principle of buoyancy — an object displaces its own volume of fluid — reportedly while stepping into a bath. Also gave us the law of the lever ("give me a place to stand and I will move the Earth").
The scientific revolution — 1600s
The century physics stopped trusting pure reasoning and started trusting measurement.
Galileo Galilei
As the story goes, dropped two different masses from the Leaning Tower of Pisa and watched them land together — direct evidence against Aristotle. His careful, repeatable inclined-plane experiments on falling bodies (and his telescope, aimed at Jupiter's moons) helped invent the idea of testing an idea at all.
Try it: Free fall mode →Johannes Kepler
Worked out, from Tycho Brahe's painstaking naked-eye observations, that planets move in ellipses rather than perfect circles, sweeping equal areas in equal times. Newton would later show these laws fall straight out of a single inverse-square force.
Christiaan Huygens
Built the first working pendulum clock, turning Galileo's observation that a pendulum's swing keeps steady time into an actual precision instrument. Also proposed that light travels as a wave, decades before anyone could prove it.
Try it: Pendulum & SHM mode →Isaac Newton
The apple story is likely simplified but not invented — Newton himself later described watching an apple fall at his mother's farm in 1666 and wondering whether the force pulling it down also reaches the Moon. That question grew into the three laws of motion and universal gravitation, published in the Principia (1687) — the single book that mechanics.html is built on.
Try it: Mechanics playground →Electricity & magnetism — 1700s–1800s
Two "separate" forces turn out to be one and the same thing.
Charles-Augustin de Coulomb
Used a delicate torsion balance to measure the force between two charges directly, finding it falls off as the inverse square of the distance between them — the exact electrical mirror of Newton's law of gravitation.
Try it: Electrostatics mode →Alessandro Volta
Stacked alternating discs of zinc and silver separated by brine-soaked cloth and got a steady electric current out of it — the voltaic pile, the first true battery, and the ancestor of every "Battery EMF" slider in the circuit builder.
Try it: Circuit builder →Hans Christian Ørsted
Noticed, during a lecture demonstration, that a compass needle placed near a current-carrying wire twitched and turned — the first direct evidence that electricity and magnetism are connected, not separate forces at all.
Try it: Electricity & magnetism lab →André -Marie Ampère
Turned Ørsted's surprising observation into hard mathematics within weeks — working out how the strength of the magnetic effect relates to the current that causes it. The SI unit of current, the ampere, is named for exactly this work.
Try it: Electricity & magnetism lab →Georg Simon Ohm
Showed, through careful measurement, that the current through a conductor is directly proportional to the voltage across it — V = IR — a relationship so fundamental it's the very first thing the circuit builder's formula sheet teaches.
Try it: Circuit builder →Michael Faraday
Pushed a magnet through a coil of wire and found current flowed only while the magnet was moving — never while it sat still inside. Electromagnetic induction, ε = −N dΦ/dt, is the whole reason a moving magnet can light a bulb, and it's the exact experiment the Induction mode recreates.
Try it: Induction mode →James Clerk Maxwell
Wrote down four equations that unified electricity, magnetism and light into a single theory, and predicted that changing electric and magnetic fields should propagate through space as waves — travelling, his own equations said, at exactly the speed of light. They were radio waves, discovered for real two decades later.
Try it: AC circuit mode →Light & heat — 1800s
Is light a wave or a stream of particles? And what is heat, really?
Thomas Young
Shone light through two narrow slits and, instead of two bright bands, saw a whole striped pattern of bright and dark fringes on a screen behind them — the unmistakable signature of two overlapping waves interfering. This single experiment settled, for over a century, that light is a wave — the same constructive/destructive rule the Interference mode lets you build yourself.
Try it: Interference mode →Sadi Carnot
Asked a purely practical question — how efficient can a heat engine possibly be? — and found a surprising universal answer that depends only on the temperatures it runs between, laying the theoretical foundation for the second law of thermodynamics.
Try it: PV diagram mode →James Prescott Joule
Used a falling weight to turn a paddle wheel inside an insulated tank of water and measured exactly how much the water warmed up — showing that mechanical work and heat are the same kind of thing, interchangeable at a fixed, measurable rate.
Into the atom — 1890s–1930s
Matter turns out to be almost entirely empty space, built from pieces nobody had ever seen directly.
J.J. Thomson
Fired cathode rays through electric and magnetic fields inside a vacuum tube and showed they were made of particles far lighter than any atom, and negatively charged — the first evidence that atoms aren't indivisible at all. He'd found the electron.
Marie Curie
Coined the term "radioactivity" and, working with almost nothing but raw pitchblende ore, isolated two brand-new elements — polonium and radium. The only person ever to win Nobel Prizes in two different sciences (Physics, then Chemistry).
Try it: Modern physics explainers →Max Planck
To explain the exact colour spectrum glowing-hot objects give off — a problem classical physics simply couldn't solve — proposed that energy is only ever emitted in discrete little packets, or "quanta." He called it a mathematical trick; it turned out to be the opening move of quantum mechanics.
Try it: Photoelectric effect explainer →Ernest Rutherford
Had his students fire alpha particles at an ultra-thin gold foil, expecting them all to sail straight through. Almost all of them did — but a tiny fraction bounced back at sharp angles, some almost straight back the way they came. His own words: "as if you had fired a fifteen-inch shell at a piece of tissue paper and it came back and hit you." Atoms are mostly empty space with all their mass and charge crammed into a tiny central nucleus.
Try it: Bohr model explainer →Niels Bohr
Solved a problem Rutherford's own model couldn't answer — why don't orbiting electrons just spiral into the nucleus? — by proposing electrons can only occupy certain fixed, quantised orbits. It correctly predicted hydrogen's line spectrum, and it's the picture the Bohr model explainer animates directly.
Try it: Bohr model explainer →Albert Einstein
In a single, staggering year (1905) explained the photoelectric effect by treating light itself as a stream of discrete energy packets — photons — and published special relativity. His 1921 Nobel Prize was specifically for the photoelectric work, not relativity, because it was the more immediately verifiable physics.
Try it: Photoelectric effect explainer →James Chadwick
Found the last missing piece of the atom: a particle with almost the same mass as a proton but no electric charge at all — the neutron. It finally explained why different isotopes of the same element have different masses.
Try it: Modern physics explainers →The digital age
The last link in the chain — from pure logic to the switch inside every gate you've built in this lab.
George Boole
Invented an entire algebra where the only two values are true and false — AND, OR and NOT as mathematical operations. Nobody at the time had any use for it. Almost a century later, it turned out to be exactly the mathematics needed to design digital circuits.
Try it: Logic gate lab →Bardeen, Brattain & Shockley
Built the first working transistor at Bell Labs — a solid-state switch with no moving parts, no glowing filament, and a fraction of the size of the vacuum tubes it replaced. Every AND, OR and NOT gate you've wired together in the logic gate lab is, underneath, millions of these switches doing exactly the job Boole's algebra describes.
Try it: Logic gate lab →Why this page exists
Part of Forces — see Learn for the class 9–12 syllabus these tie back to.