This plaque marks the spot where Sir William Rowan Hamilton, arguably Ireland’s greatest scientist, invented a revolutionary new algebra in 1843. His ‘quaternions’ describe things moving in 3D, and are now used to orient spacecraft, in 3D animations and computer games. You could say that they helped to land a man on the Moon!
They also broke the fundamental commutative law of multiplication. Hamilton lived and worked nearby, at Dunsink Observatory, and made important contributions to dynamics, the foundations of quantum mechanics, and optics. The audio guided walking tour, Quaternions by the Royal Canal, has the story.
Facilities, visiting: the plaque is by the canal, at the railway bridge. There are no facilities. Each year, there is a commemorative walk from Dunsink Observatory along the canal to Broom Bridge on October 16, the anniversary of the date when Hamilton invented quaternions.
For more information:
Quaternions in Wikipedia