Sir, – An Irishwoman’s Diary (October 5th) provided an enjoyable summary of the life of William Rowan Hamilton, Ireland’s most distinguished scientist, and his most famous contribution to mathematics, quaternions (from a biblical term for four Roman soldiers). However, lest your readers be left with the unfortunate impression that Hamilton’s only legacy was to facilitate a dubious form of entertainment for teenage boys, I would like to point out that quaternions have applications well beyond computer animation.
In particular, quaternions are ubiquitous in applications in which a computer controls the orientation of an object in three-dimensional space (3D). Controlling artificial satellites is a prime example.
Satellites, on which our contemporary society is so heavily dependent for communications, GPS, etc, utilise quaternions to calculate how to orientate themselves in space. Unless the antenna on a satellite is precisely aligned with its target on Earth it is useless. As many computer games involve the simulation of motion in 3D they too utilise quaternions.
In fact, quaternions are not even Hamilton’s greatest legacy. That would be the fundamental advances he made in the branch of physics known as mechanics, which deals with the motion of objects, eg planets and satellites, under the influence of forces such as gravity. Hamilton’s full legacy will be celebrated in 2012 when Dublin hosts Europe’s largest general science meeting, the Euroscience Open Forum. – Yours, etc,