David Tong: the human soliton

By Hamish Johnston

Our colleagues at the Institute of Physics in London are making a series of videos called Physics Lives that focuses on university research physicists and what they do in their working lives. The latest production stars David Tong, who is Professor of Theoretical Physics at the University of Cambridge, and you can watch it right here.

Tong is a big fan of solitons, so you might wonder why his video “Baths and Quarks” begins with him lying motionless in the bath and then blowing bubble rings. “Baths would be so much more relaxing if they weren’t so interesting,” he says. Then he pulls the plug and marvels at the vortex formed when the water goes down the drain.

“My job is to understand the beautiful things in the world that surrounds me,” he says, and points out that both the bubble rings and the vortex can be understood in terms of solitons.

The video continues with some lovely shots of water vortices, smoke rings and colliding marbles – all explained in a soothing dreamlike manner by Tong. Then the video moves on to Tong’s research on quarks, and he explains why solitons could hold the key to understanding the strong force, which binds together quarks in hadrons such as protons and neutrons.

A fundamental understanding of the strong force would involve establishing the mathematical basis underpinning Yang–Mills theory – which in 2000 was deemed one of the seven important challenges facing mathematicians by the Clay Mathematics Institute. Indeed, the US-based institute thinks the problem so important that it’s offering a cool $1m to anyone who can solve it.

So it’s back into the bath for Tong, where he says he does some of his best thinking. You can view all four videos in the Physics Lives series here.

The videos include “Ion Beam Cop”, in which Melanie Bailey of the University of Surrey does some forensic physics, and “Written in the Sky”, in which Jim Wild of the University of Lancaster flies to Iceland to investigate the mysteries of the aurora borealis.