When each idea was found
Courses teach the ideas in a tidy order. People found them in a messy one: gold was known long before anyone knew what an element was, and a Babylonian scribe used Pythagoras' theorem over a thousand years before Pythagoras.
Prehistory · Chemistry
Gold · Known since prehistory; the oldest gold jewellery yet found, from Varna in Bulgaria, is about 6,500 years old · symbol from Latin aurum1800 BC · Math
Pythagoras' theorem · Babylon, about 1800 BC · proved by Greeks about 500 BC1650 BC · Math
The π Mystery · Rhind Papyrus approximation, Egypt, about 1650 BC · Archimedes' bounds, 3rd century BC3rd century BC · Chemistry
Density · Archimedes' law of buoyancy, 3rd century BC1st century AD · Math
Percent change · Roman 1 % sales tax under Augustus, 1st century AD (per centum = per hundred)1687 · Physics
Newton's second law · Isaac Newton, 16871772 · Chemistry
Oxygen · Carl Wilhelm Scheele (Sweden), about 17721779 · Biology
Photosynthesis · Jan Ingenhousz showed light is needed, 17791827 · Physics
Ohm's law · Georg Ohm, 18271847 · Physics
Energy conservation · Mayer, Joule and Helmholtz, 1840s1953 · Biology
DNA · Double-helix structure: Franklin, Watson, Crick and Wilkins, 1953 · DNA itself was first isolated by Friedrich Miescher in 1869