Most of the electricity you use comes from an experiment done in 1831.
Michael Faraday moved a magnet through a coil of wire and found it produced an electric current. This is electromagnetic induction — the principle inside every generator.
Why it matters: Power stations, from Tarbela's turbines to wind farms, still generate electricity this way.
Experimental Researches in Electricity — Michael Faraday (1831) Philosophical Transactions of the Royal Society, 1832
For centuries, people believed our eyes send out rays in order to see.
Ibn al-Haytham tested this with experiments, including a dark room with a small hole, and showed that we see because light travels from objects into the eye.
Why it matters: His insistence on testing ideas by experiment helped shape the scientific method.
Kitab al-Manazir (Book of Optics) — Ibn al-Haytham (Alhazen) (c. 1011–1021)
A tiny amount of mass holds an enormous amount of energy.
In 1905 Einstein showed that mass and energy are two forms of the same thing, linked by the speed of light squared. This is why stars can shine for billions of years.
Why it matters: It is the principle behind nuclear power stations and the energy of every star.
Does the Inertia of a Body Depend Upon Its Energy Content? — Albert Einstein (1905) Annalen der Physik, 1905
Three short rules explain how everything from a cricket ball to a rocket moves.
In 1687 Newton set out his laws: objects keep their motion unless a force acts; force equals mass times acceleration; every action has an equal and opposite reaction.
Why it matters: Every car, bridge and satellite is still designed using these three laws.
Philosophiæ Naturalis Principia Mathematica — Isaac Newton (1687) Book I, Axioms, or Laws of Motion