In 1628 a short, badly printed book of seventy two pages appeared in Frankfurt. Its author was the physician to the King of England, and its argument was that the accepted account of what blood does in the body, taught without serious challenge for fourteen centuries, was impossible on arithmetical…

Plenty of chemists in the 1860s noticed that the elements fall into repeating patterns. Several published tables. What separates Dmitri Mendeleev from all of them is that he trusted his arrangement more than he trusted the data, left holes where he believed elements were missing, and described in detail what…

Ernest Rutherford described the result as the most incredible event of his life. It was, he said, almost as if you had fired a fifteen inch shell at a piece of tissue paper and it had come back and hit you. The shell was an alpha particle. The tissue paper…

In April 1897, J.J. Thomson told the Royal Institution that he had found something smaller than an atom. The reaction in the room was polite scepticism. One senior colleague told him afterwards that he had assumed the whole talk was an elaborate joke. The reaction was reasonable. The atom had…

The idea that matter is made of indivisible particles is ancient. Democritus proposed it in the fifth century BC, Lucretius wrote a poem about it, and for the next two thousand years it remained exactly what it had always been: a philosophical position, argued about but never tested. What John…

In sixteenth century Italy, a mathematician could lose his job in an afternoon. University positions were defended through public challenges: two opponents each submitted a list of problems, both worked in private for a fixed period, and whoever solved more problems in front of witnesses kept the chair and the…

No scientific book has ever held authority for as long as the Almagest. Written in Alexandria around 150 AD by Claudius Ptolemy, it remained the standard reference for predicting the positions of the planets until the sixteenth century. Fourteen hundred years is a long run for any theory, and it…

In the summer of 1797, in a garden shed in Clapham, one of the richest and shyest men in England began measuring a force roughly ten million times weaker than the weight of a grain of sand. He worked alone, watched his apparatus through telescopes bored into the shed walls…

In 1543 a twenty eight year old professor at Padua published a book that did two things at once. It corrected around two hundred errors in the anatomical authority that European medicine had trusted for thirteen centuries, and it looked better than any scientific book that had ever been printed.…

Two words in everyday scientific English come from the same ninth century scholar working in Baghdad. One of them is algebra, from the Arabic al-jabr, the title of his most famous book. The other is algorithm, which is a mangled Latin transcription of his name. Not many people leave that…