Happy Birthday, Quaternions!

Sir William Rowan Hamilton (1805-1865)

Today, October 16th, is Hamilton day! It was on this day 176 years ago, in 1843, that  William Rowan Hamilton first wrote down the fundamental result of quaternions. Apparently he was walking from his residence at Dunsink Observatory into Dublin when he had a sudden flash of inspiration  and wrote the result down on the spot, now marked by a plaque:


Picture Credit: Brian Dolan

This episode  is commemorated by an annual Hamilton Walk. Sadly,  Broombridge (Droichead Broome) is near the bridge (Broom Bridge) where Hamilton had his Eureka moment and it is on the main commuter line from Maynooth into Dublin. This is ironic because Quaternion algebra does not commute. (Geddit?)

Although it is quite easy to reach Broombridge from Maynooth, I sadly can’t attend the walk this year because I’m teaching this afternoon.

P.S. Maynooth is also home to the Hamilton Institute which promotes and facilitates research links between mathematics and other fields.

4 Responses to “Happy Birthday, Quaternions!”

  1. The verb “commute” has a really interesting etymology. The sense of “cut short” is still around, as in “commuted prison sentence”. A commuter was one who travelled enough that it was worth it to buy a monthly pass, whose price was cut short, commuted, as a discount; such people became known as “commuters”, hence “commuter” meaning “regular travel”.

    I learned this from Peter Atkins. Extra credit if you can guess how.

    A similar word with an obvious, though to most people lost, etymology is “journey”. Related to French “journée”, it originally denoted a day’s travel, thus “a journey of a week” would be an oxymoron, but not anymore, since the original meaning has been lost.

    Similarly, a journeyman is not a worker who journeys around, but rather someone (between an apprentice and a master) who, while he could not have his own apprentices, was qualified enough to be paid for a day’s work.

    Interestingly, in many places a long time ago, and to some extent still in Germany today, one qualification to become a master was, as a journeyman, actually to travel from place to place, avoiding one’s home for a certain time (and wearing traditional dress to differentiate oneself from a beggar):

    I doubt that this is a source of confusion, though, since the only cognate of “journée” in German is “Journal”, i.e. (originally) a daily publication. (And, in French, a magazine which appears every seven days, once a week, is a “hebdomadaire”, hence Charlie Hebdo.)

    Note: there are only two things as interesting as cosmology and etymologie. One of them is music. 🙂

  2. Anton Garrett Says:

    Do people who live in the city and work in the country anticommute?

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