Solving a physics mystery: Those 'solitons' are really vortex rings

February 3, 2014 by Peter Kelley
An example of a vortex ring, also called a toroidal bubble, which dolphins create under water. The concept of vortex rings lies at the heart of new University of Washington physics research.

( —The same physics that gives tornadoes their ferocious stability lies at the heart of new University of Washington research, and could lead to a better understanding of nuclear dynamics in studying fission, superconductors and the workings of neutron stars.

The work seeks to clarify what Massachusetts Institute of Technology researchers witnessed when in 2013 they named a mysterious phenomenon—an unusual long-lived wave traveling much more slowly than expected through a gas of cold atoms. They called this wave a "heavy soliton" and claimed it defied theoretical description.

But in one of the largest supercomputing calculations ever performed, UW physicists Aurel Bulgac and Michael Forbes and co-authors have found this to be a case of mistaken identity: The heavy solitons observed in the earlier experiment are likely vortex rings – a sort of quantum equivalent of smoke rings.

"The experiment interpretation did not conform with theory expectations," said Bulgac. "We had to figure out what was really happening there. It was not obvious it was one thing or another—thus it took a bit of police work."

A vortex ring is a doughnut-shaped phenomenon where fluids or gases knot and spin in a closed, usually circular loop. The physics of vortex rings is the same as that which gives stability to tornadoes, volcanic eruptions and mushroom clouds.

Dolphins actually create their own vortex rings in water for entertainment:

"Using state-of-the-art computing techniques, we demonstrated with our simulation that virtually all aspects of the MIT results can be explained by vortex rings" said Forbes, an UW affiliate professor who in January became an assistant professor of physics at Washington State University.

He said the simulations they used "could revolutionize how we solve certain physics problems in the future," such as studying nuclear reactions without having to perform nuclear tests. As for , he said the work also could lead to a better understanding of "glitches," or rapid increases in such a star's pulsation frequency, as this may be due to vortex interactions inside the star.

"We are now at a cusp where our computational capabilities are becoming sufficient to shed light on this longstanding problem. This is one of our current directions of research—directly applying what we have learned from the ," Forbes said.

The computing work for the research—one of the largest direct numerical simulations ever—was performed on the supercomputer Titan, at the Oak Ridge Leadership Computing Facility in Tennessee, the nation's most powerful computer for open science. Work was also performed on the UW's Hyak high-performance computer cluster.

Explore further: How Earth's rotation affects vortices in nature

More information: Bulgac and Forbes published their findings in a January issue of Physical Review Letters:

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5 / 5 (1) Feb 03, 2014
Great news. At last some bleeding edge research that reduced the complexity of current scientific vocabulary. 'Heavy solitons'... meh.

I wonder how many other exotic 'particles' can be simplified and explained away in similar ways :D
5 / 5 (2) Feb 03, 2014
Many videos and simulations of these solitons can be found here.
not rated yet Feb 03, 2014
Great article and video. The work of Hermann von Helmholtz (August 31, 1821 – September 8, 1894) started this amazing world. There is a great depth to the description of particles using vortexes, keep the research coming.

5 / 5 (1) Feb 04, 2014
I wonder how many other exotic 'particles' can be simplified and explained away in similar ways :D

Correct me if I'm getting this wrong, but I don't think a soliton was supposed to be a particle. A soliton is a type of wave, which can occur in particles, but can also happen in light or magnetic fields. The heavy soliton was an experimental result where 'something' was causing the mass measurement to jump upwards under certain conditions. They already suspected it was a soliton wave of some type (there are many types of solitons), but none of the existing soliton solutions fit this case. The new results above simply allow a mathematical solution that explains the soliton in the experiment.
5 / 5 (1) Feb 04, 2014
Infinum/GSwift: To add on: It's more like a particulate solution of a working field theory. Not a *fundamental particle* that makes stuff up, but a specific excitation of a field used to describe some situation.
not rated yet Feb 04, 2014
[duplicate comment]
not rated yet Feb 04, 2014
[triplicate comment. Geez Physorg, just let me delete things]
not rated yet Feb 04, 2014
A soliton is a type of wave, which can occur in particles, but can also happen in light or magnetic fields
In water surface analogy of space-time the neutrino correspond the Falaco solitons and photons the Russel's solitons. The first type is more similar to particle, the second one more similar to wave. You can even deduce testable predictions from this analogy, for example regarding the neutrino speed, which can never fall to zero.
not rated yet Feb 10, 2014
I've been saying this since I was in high school. Look at the movie at 0:23 after it breaks the small ring from the big one what happens to the rest of the big one. Tell me that that doesn't look like a decaying particle after a collision. But people won't take this into consideration, because then they would have to reconsider the luminiferous aether-like-substance theory (because you need a medium to do stuff like this) and in turn the particle-wave duality of light and god knows what else. Nobody wants to get his hands this dirty.

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