The word genius is defined as ‘a person who displays exceptional intellectual ability, creativity or originality associated with the achievement of new advances in a domain of knowledge’ and it most definitely applies to William Rowan Hamilton.
Hamilton was born on the 4th August 1805, the fourth of nine children, to Archibald Hamilton, a solicitor, and his wife Sarah and lived at 38 Dominick Street, Dublin. When he was three years old he was sent to live with his uncle James Hamilton, a teacher and linguist, who ran a school in Trim, County Meath, and showed an exceptional talent for languages from an early age. By the age of thirteen he had acquired the same number of languages, including ancient Latin and Greek, most modern European languages and Persian, Arabic and Sanskrit. Late in life he often relaxed by reading books in Persian or Arabic!
When he was eight he lost a mental arithmetic contest against the American prodigy Zerah Colburn who was touring Europe and astounding audiences with his ability. After his loss Hamilton devoted his time to mathematics and less to the study of languages. The year before he entered university he spotted an error in Laplace’s Mechanique Celeste, and this brought him to the attention of John Brinkley, the Royal Astronomer of Ireland. He said of Hamilton: ‘This young man, I do not say will be, but is, the first mathematician of his age.’
He entered Trinity College when he was eighteen and studied mathematics and Classics gaining an unprecedented ‘optime’ in both. Soon afterwards, in 1827, he was appointed, while still an undergraduate, Professor of Astronomy at Trinity College. Although this was a great opportunity for Hamilton, which included a decent salary and the title of Royal Astronomer of Ireland, it was also a place for his sisters to live. However, he spent most of his time studying mathematics and very little effort was devoted to astronomy. He was, however, twice awarded the Cunningham Medal, the highest honour bestowed by the Royal Irish Academy. And in 1835 he was knighted for his services to science; and both he and Michael Faraday were awarded the Queen’s Medal by the Royal Society that same year.
While on his way along the Royal Canal to a meeting in the Royal Irish Academy on 16th October 1843 the discovery of quaternions took shape in his mind. He etched the equation on Broome Bridge and the famous event is celebrated each year with a walk from the observatory to the site. Today quaternions are used in computer graphics, signal processing and orbital mechanics. As such, their use can be found in todays’ spacecraft attitude-control systems, and their discovery played a significant role in putting Man on the Moon. That’s out of this world, and something the Dunsink Astronomer would have loved.