10. William Rowan Hamilton

[Narration] Stand here for a moment and look at the bridge in front of you. Then look up at the plaque above.

Now, let’s jump back to 1843, when Sir William Rowan Hamilton was one of Ireland’s brilliant brain boxes. He was a mathematician, physicist, and astronomer, and worked at the Royal Astronomer of Ireland at Dunsink Observatory, where he spent most of his life.

For over a decade, Hamilton struggled to understand how numbers could work in three dimensions. He was working on a major problem in mathematics, basically how to describe rotations and directions in three-dimensional space using algebra.

Jaysus, that’s a long time to be confused for.

Anyway, Hamilton often walked along the Royal Canal here to think about his mathematical problems. One day in 1843, he was walking down the canal , from Dunsink Observatory towards the Royal Irish Academy with his wife, Helen.

Then...

Right there at Broom Bridge, he had a lightbulb moment.

A mathematician's moment.

What does he do? Stop and tell his wife?

No.

Then Hamilton pulled out a penknife and, he couldn't resist the urge and carved the equation on this bridge.

That formula became known as quaternions.

Later, he described the moment in a letter to his son, writing: “Nor could I resist the impulse, unphilosophical as it may have been to cut with a knife on a stone of Brougham Bridge as we passed it, the fundamental formula.”

While the original carving is no longer present. If you look up, there is a plaque remembering Hamilton’s discovery. It was placed by the Dublin Institute for Advanced Studies in 1958.

The impact of quaternions was huge. They opened up new ways of doing algebra that didn’t follow the usual rules of multiplication. These ideas later became essential in physics, navigation, computer graphics, and animation, especially for representing rotation in three-dimensional space.

This new number helped create modern CGI and computer graphics, aided navigation systems, and even helped put the first man on the moon.

In other words, quaternions help power modern CGI, video games, and even spacecraft tracking. So next time you’re watching an action movie packed with CGI. Just thank Hamilton himself.

Every year on October 16th, known as Hamilton Day, people walk from Dunsink Observatory to Broom Bridge to remember the brilliance of Hamilton, right here in Cabra west.

This brings us to the end of the tour. I would really like to thank you for participating in my final year project. If you enjoyed this tour, please feel free to share it with family and friends.

If you wish, there is also a feedback form available on the website where you can share your overall thoughts or suggest any improvements we could make to this project.

Thank you, Alex

[Music Refernce] Music: “Towards the Horizon” by Alexander Nakarada (via Pixabay)