twists
snaps &
swirls
in
How turbulence plays out in exotic materials
By Marissa Cevallos
Grab a mug and slosh the morning coffee around and around and a spinning vortex appears. The swirling rings,
with their eddies and choppy waves,
obey the laws of classical turbulence,
which engineers and applied physicists
routinely invoke to study how air flows
over an airplane wing or how blood flows
through tiny vessels.
Sometimes these lines tangle like a ball
of cat hair on a rug. And they can cross
over each other into a letter X, swap
ends and then shoot away with the
gusto of a rubber band flinging from the
finger of a mischievous third-grader.
Such scenarios go far beyond break-fast-table turbulence. This is the strange
world of quantum turbulence, which
pops up not in coffee cups, but in supercold helium, other types of strange cold
matter and, some now think, the fabric
of the universe.
Physicist Richard Feynman predicted
the existence of quantum vortices more
than half a century ago. But only in the
last few years have physicists actually
been able to watch the vortices’ behav-
ior with the naked eye. Researchers are
now stirring up quantum liquids to see
whether Feynman’s ideas were correct,
and going a step beyond to find out in
fuller detail what happens as a slosh-
ing quantum fluid rocks to rest. Under-
standing turbulence in these fluids may
also offer clues to astrophysical myster-
ies — violent ejections of gas from the sun
may obey the same strange dynamics, and
thinking of the early universe as a fabric
riddled with such vortices might help
explain unexpected voids in the cosmos.
Theoretical swirlings
The rules of physics changed dramatically with the arrival of quantum
mechanics, which describes how tiny
particles such as electrons play. In the
quantum world, particles can act like
