Who Was William Rowan Hamilton? Irish Genius Who Transformed Math and Physics

By Steven Galvin - Last update

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Today in 1843, the theory of quaternions was born when a sudden thought came to William Rowan Hamilton as he was walking with his wife along the Royal Canal in Dublin, Ireland. It was the fundamental formula: i² = j² = k² = ikj = -1. So, Who Was William Rowan Hamilton? And What are Quaternions?

Born in 1805, William Rowan Hamilton was a child prodigy turned influential scientist who blazed new trails in mathematics and physics that still reverberate today. Hailed as one of Ireland’s great minds, Hamilton left a legacy of revolutionary ideas and formulae that changed science forever.

Mastering Languages and Math

Even as a young boy, Hamilton displayed an exceptional gift for absorbing languages and mathematics. He was appointed Professor of Astronomy at Trinity College Dublin while still an undergraduate, grasping complex concepts far beyond his years.

Pioneering Hamiltonian Mechanics

Hamilton’s most seminal work was in reformulating Newtonian mechanics by describing motion in terms of energy instead of force. His Hamiltonian mechanics uses Hamilton’s equations to link energy, position and momentum. This innovative approach provided deeper insights into dynamics.

Inventing Quaternions

In math, Hamilton invented quaternions – extensions of complex numbers into 4-dimensional space. These non-commutative hypercomplex numbers unlocked new understanding of spatial rotations and multidimensional space. Quaternions now have many physics and geometry applications.

Advancing Optics

Equally comfortable in the lab, Hamilton studied optics and predicted the phenomena of conical refraction, where rays curve into a cone shape under certain crystals. His Hamiltonian optics improved understanding of ray behaviour and wave theory.

Tortured Genius

Despite his brilliance, Hamilton struggled with alcoholism and severe depression. Yet, he maintained an astounding output of papers and books that ensured his lasting legacy. Hamilton’s groundbreaking work established him as a giant of 19th century science.

So by pioneering advances like Hamiltonian mechanics and quaternions, the Dubliner William Rowan Hamilton made his mark as one of history’s great scientific minds and Ireland’s most influential polymath.


In essence, quaternions shine in any application involving smooth, reliable representations of rotations and orientation in 3D space. Their elegance and usefulness persist long after Hamilton conceived them in 1843.Here are some key examples of how quaternions are used in modern technologies and applications:

  • Computer graphics – Quaternions are used to represent rotations and interpolate between orientations in 3D animation and graphics. This provides smooth, efficient transitions.
  • Game development – Quaternions enable seamless blending of character and camera orientations in virtual worlds for a natural look. They avoid problems with gimbal lock.
  • Robotics – Quaternion-based control and coordinate systems are used in robotics for navigation, inverse kinematics, and representing end-effector and manipulator orientations.
  • Spacecraft attitude control – NASA and SpaceX use quaternions rather than Euler angles for stable 3D orientation control and maneuvers of spacecraft.
  • Motion tracking – Sensor fusion algorithms utilize quaternions to combine data from gyroscopes, accelerometers and magnetometers for accurate tracking of position and orientation.
  • Computer vision – Quaternions help estimate camera pose and geometry from images. They parameterize rotations in bundle adjustment algorithms.
  • Physics simulation – Modeling orientation behavior of rigid bodies in physics engines for games and animations is done using quaternions.
  • Crystallography – Quaternions describe symmetry operations like rotation, inversion and improper rotation of crystals and molecular structures.


Steven Galvin

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