The Last Man Who Knew Everything
He proved light is a wave, explained the eye, named energy’s elastic limits, and helped crack Egypt’s hieroglyphs — as a hobby.
When the historian Andrew Robinson wrote the standard biography of Thomas Young in 2006, the title chose itself: The Last Man Who Knew Everything. The claim is extravagant. The case, reviewed honestly, is stronger than the title.
The résumé that reads like a committee
Thomas Young (1773–1829) was a practising London physician. In the margins of that career he:
- Proved light behaves as a wave. His double-slit experiment — light passing through two openings and interfering like ripples — overturned a century of Newtonian orthodoxy and remains the most famous experiment in physics, now the standard demonstration of quantum mechanics' central mystery.
- Founded the physiology of vision. He showed the eye focuses by changing the lens's shape, described astigmatism, and proposed that colour vision rests on three receptor types — the trichromatic theory, confirmed by microscopy 150 years later.
- Gave engineering its measuring stick. Young's modulus, the ratio by which every material's stiffness is still specified, appears in essentially every structural calculation performed on Earth today.
- Helped crack the hieroglyphs. Working from the Rosetta Stone, Young established that the demotic script mixed phonetic and symbolic signs and worked out sound values in royal cartouches — the platform from which Champollion, with superior knowledge of Coptic, achieved full decipherment. The rivalry (and the division of credit) between the two men remains a favourite dispute among Egyptologists; Young's own contributions are documented in the Encyclopaedia Britannica article "Egypt," which he wrote.
He also studied the mechanics of blood flow, proposed a theory of tides, compared the vocabularies of hundreds of languages (coining the term "Indo-European"), tuned musical temperaments, and contributed dozens of anonymous encyclopedia articles on subjects from "Bridge" to "Weights and measures" — anonymous because a physician known to do so many other things might alarm his patients.
The child behind the polymath
The range announced itself early: by the accounts of his family and biographers, Young had read the Bible through twice by the age of four and by his mid-teens had worked through Latin, Greek, Hebrew, Arabic and several modern languages. Fellow students at Cambridge nicknamed him, without much affection, "Phenomenon Young." He belongs among the great child prodigies — with the difference that his adult range exceeded even his childhood's.
Why "the last"?
The phrase is a verdict on history, not just on Young. In 1800, one exceptional mind could still hold the research frontier of physics, physiology, linguistics and engineering simultaneously — Young was arguably the final person to do so at the first rank. Within a generation, specialisation made the feat structurally impossible; our survey of the great polymaths ends, in effect, with him. His contemporary Alexander von Humboldt — the naturalist whose name marks currents, penguins and mountain ranges — made the same last stand in the sciences of the Earth; the two men effectively closed the age of universal knowledge together.
<iframe width="560" height="315" src="https://www.youtube.com/embed/CY8zxIoQhh8" title="Phenomenon: The Life of Thomas Young" frameborder="0" allowfullscreen loading="lazy"></iframe>"It is probably best to acknowledge at once that no man can be said to know anything until he knows how little he knows."
— Thomas Young
Watch: Phenomenon: The Life of Thomas Young
The measure of the loss
Young died at 55, his collected working papers a map of a mind with no borders. His epitaph in Westminster Abbey calls him "a man alike eminent in almost every department of human learning." The word doing the work in that sentence — almost — is the last trace of an era when it needed to be there at all.
Frequently Asked Questions
Why is Thomas Young called the last man who knew everything?
The title of Andrew Robinson's biography reflects Young's first-rank work in physics, physiology, engineering and Egyptology — a range specialisation soon made impossible.
What is Young's most famous experiment?
The double-slit experiment, which proved light behaves as a wave and is now the standard demonstration of quantum mechanics' central mystery.
Did Young or Champollion decipher the hieroglyphs?
Young made key early steps — sound values and the mixed nature of the scripts — while Champollion achieved the full decipherment; historians credit both.