Baths and Quarks: Understanding solitons

Professor David Tong, Department of Applied Mathematics and Theoretical Physics at the University of Cambridge, talks about the unique qualities of solitons and their special relationship with quarks.


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Professor David Tong spends a lot of time in the bath. For him, this is work. Lying in the bath, he thinks about the problem that he has been working on for five years.

“Baths would be so much more relaxing if they weren’t so interesting,” David says.

“There are so many amazing things; bubble rings. There’s something strange and unnatural about these objects. Some structure where you wouldn’t expect to see structure.

“Objects like these may just hold the key to one of the most important problems in physics.”

It is a problem which has been troubling scientists for 40 years, and is regarded as one of the seven important problems in mathematics. And there’s a $1 million prize waiting for whoever is able to solve it.

David is a theoretical physicist. He uses the language of mathematics to describe the beautiful things that he sees in the world around him. His interest is in solitons, a form of solitary wave which he sees in the form of bubble rings in the bath and the vortex as the bathwater runs away when he pulls the plug.

Solitons are David’s real passion. They make it impossible to separate quarks from protons, ultimately holding together the entire universe. Yet nobody understands how this works.

Named solitons thanks to their unique qualities, they require very special conditions to form, as David demonstrates when he places his hand in water and swills it around, moving the entire body of water as one.

“Solitons are beautiful objects. But as I look deeper into the world, at smaller and smaller distances, I see solitons everywhere,” he says.

“And right at the very heart of matter, solitons hold the answer to the most important question: what is holding everything together?”

David also explores the unique relationship shared by solitons and quarks.

“The strange thing about a quark is: no-one’s ever seen one on its own.

“If you try to pull a quark out of a proton, a soliton forms, pulling the quark back into the proton. And that’s what holds everything together.”

We follow David in his day-to-day life as he works on a problem that has taxed some of the greatest minds in physics. We get a glimpse at the processes he uses as a physicist and see what drives him. Ultimately, it’s simple. “There is something really fundamental and important about the universe that we don’t understand,” he explains. “And that really bugs the hell out of me.”


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Baths and Quarks by The Institute of Physics as part of the National HE STEM Programme is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.

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