Nobel Prize-winning theoretical physicist Chen-ning Yang, died in Beijing on Saturday at the age of 103.

He was often ranked alongside Albert Einstein as one of the 20th century’s greatest physicists.

In 1954, he co-authored a set of equations with the American physicist Robert Mills that turned out to be as important to physics as Einstein’s theory of relativity.

The resulting Yang–Mills theory described how three of nature’s four fundamental forces — the electromagnetic, weak and strong interactions — operate in the subatomic world.

It laid the mathematical foundation for what later became known as the Standard Model, the cornerstone of modern physics that unifies these forces and explains the behaviour of all known elementary particles.