William Rowan Hamilton

On this day Irish physicist, astronomer, and mathematician Sir William Rowan Hamilton was born. Hamilton is best known for his reformulation of Newtonian mechanics, now called Hamiltonian mechanics, the lynchpin of classical studies such as electromagnetism, and a key development for the later study of quantum mechanics. Hamilton also made important contributions to classical mechanics, optics, and algebra. He was the fourth of nine children born to Sarah Hutton (1780–1817) and Archibald Hamilton (1778–1819), a middle class family who lived in Dublin. By the age of three, Hamilton had been sent to live with his uncle James Hamilton, who ran a school in Talbots Castle in Trim Co. Meath. His uncle, a linguist, soon discovered that Hamilton was a keen student, and picked up knowledge quickly. Before he was thirteen he had acquired most classical and modern European languages, Hebrew, Persian, Arabic, Hindustani, Sanskrit, and even Marathi and Malay. He retained much of his knowledge of languages to the end of his life. In September 1813 the American calculating prodigy Zerah Colburn was being exhibited in Dublin. Colburn was 9, a year older than Hamilton. The two were pitted against each other in a mental arithmetic contest with Colburn emerging the clear victor. In reaction to his defeat, Hamilton dedicated less time to studying languages and more time to studying mathematics. Hamilton entered Trinity College, Dublin, when he was 18. He studied both classics and mathematics, and was appointed Professor of Astronomy in 1827, taking up residence at Dunsink Observatory where he spent the rest of his life. Hamilton made important contributions to optics and to classical mechanics. His first discovery was in an early paper that he communicated in 1823 to Dr. Brinkley, who presented it under the title of “Caustics” in 1824 to the Royal Irish Academy. While their report acknowledged its novelty and value, they recommended further development and simplification before publication. Instead, the work became longer and vastly more complicated. In 1827, Hamilton presented a theory of a single function, now known as Hamilton’s principal function, that brings together mechanics, optics, and mathematics, and which helped to establish the wave theory of light. He proposed for it when he first predicted its existence in the third supplement to his “Systems of Rays”. The Royal Irish Academy paper was finally entitled “Theory of Systems of Rays,” (23 April 1827) and the first part was printed in 1828 in the Transactions of the Royal Irish Academy. In this work Hamilton developed his great principle of “Varying Action” which makes the prediction that a single ray of light entering a biaxial crystal at a certain angle would emerge as a hollow cone of rays. This discovery is still known by its original name, “conical refraction”. One of the reasons why Hamilton’s work is so widely known is because of his voluminous correspondence, usually on some aspect of his research with colleagues. Hamilton never seemed to be satisfied with a general understanding of a question until he had mastered very aspect of it. Ironically, it was because he was so excessively precise and hard to please that, despite all his personal correspondence, he published very few research papers. You can read some of them at http://www.maths.tcd.ie/pub/HistMath/People/Hamilton/ Hamilton died on 2 September 1865, following a severe attack of gout precipitated by excessive drinking and overeating. He is buried in Mount Jerome Cemetery in Dublin.

Date in History: 4 August 1805