Thomas Young: The Man Who Knew Everything

Andrew Robinson marvels at the brain power and breadth of knowledge of the 18th-century polymath Thomas Young. He examines his relationship with his contemporaries, particularly with the French Egyptologist Champollion, and how he has been viewed subsequently by historians.


Nature to him was an open book, whose letters he could read without effort. ... Reflection, refraction, the formation of images by lenses, the mode of operation of the eye, the spectral decomposition and recomposition of the different kinds of light, the invention of the reflecting telescope, the first foundations of colour theory, the elementary theory of the rainbow pass by us in procession, and finally come his observations of the colours of thin films as the origin of the next great theoretical advance, which had to await, over a hundred years, the coming of Thomas Young.

Everyone who studies physics at school is taught that Thomas Young (1773-1829) was the English scientist who first demonstrated – with a candle, a pair of narrow slits and a white screen – that light was a wave, thus disproving Newton’s conviction that it consisted of a stream of particles. Equally, anyone who studies ancient Egypt will know that Young was the linguist and antiquarian who ‘cracked’ the two Egyptian scripts on the Rosetta Stone, which then launched the full decipherment of the Egyptian hieroglyphs by Jean-François Champollion in the 1820s. Young was the first to show that demotic (the third script on the Stone, alongside Greek and hieroglyphs) to some extent resembled hieroglyphic visually, hence demotic was derived from hieroglyphic, and demotic was not an alphabet like the Greek alphabet but rather a mixture of phonetic signs and hieroglyphic signs. This thinking led Young to suggest that hieroglyphic, too, might contain some phonetic elements, an ‘alphabet’, for spelling non-Egyptian names like Ptolemy and Cleopatra.


Less well known is that Young was a physiologist who was the first to explain how the human eye focuses on objects at varying distances; who discovered the phenomenon of astigmatism; and who in 1801 proposed the three-colour theory of vision, confirmed experimentally in 1959.


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