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Colliding atom clouds bounce like billiard balls

Colliding atom clouds bounce like billiard balls

New Scientist

Image: Velo Steve

No matter how long you gaze at the clouds in the sky, you’ll never spot them behaving like those in Martin Zwierlein‘s lab at the Massachusetts Institute of Technology. Bizarrely, when two of Zwierlein’s clouds collide, they bounce off one another like billiard balls.

It’s more than a neat piece of wizardry. The feat could aid our understanding of some of the most enigmatic systems in the universe, including high-temperature superconductors, neutron stars and the soup that made up the rapidly expanding early universe.

Rain clouds, billows of smoke and most other plumes mix together when they meet. So why do Zwierlein’s clouds bounce?

The secret lies partly in the nature of the constituent particles. Instead of water droplets or dust particles, these lab-generated clouds are made of ultra-cold atoms of lithium-6. This is a rare isotope chosen because it is a “fermion”, in which each atom contains an odd number of elementary particles – the quarks that make up the protons and neutrons in the nucleus, plus the electrons that surround it. Read more on…