We’re all familiar with the classic states of matter — solid, liquid, and gas. Science is also getting quite familiar with plasma, which is now considered a fourth state. There may also be a fifth state of matter, and research aboard the International Space Station (ISS) has brought us one step closer to understanding so-called Bose-Einstein condensates.
With most materials, you can cycle through the states of matter by increasing heat. Plasma is most similar to a gas, but it’s ionized and electrically conductive. A Bose-Einstein condensate is a completely different animal. This material is dominated by quantum effects, and that makes them enormously difficult to create. On Earth, laboratories can only maintain Bose-Einstein condensates for a matter of milliseconds. However, research aboard the ISS has created a Bose-Einstein condensate that persisted for more than a second.
A Bose-Einstein condensate is so named because its existence was posited almost a century ago by Albert Einstein and Indian mathematician Satyendra Nath Bose. This exotic material only exists when atoms of certain elements are cooled to temperatures near absolute zero. At that point, clusters of atoms begin functioning as a single quantum object with both wave and particle properties. Scientists believe Bose-Einstein condensates could be the key to understanding things like dark energy and the quantum nature of the universe.
Velocity-distribution data showing Bose-Einstein condensate formation (middle and right).
Scientists create condensates by directing atoms into microscopic magnetic “traps” that coax them into a state called quantum degeneracy. Little by little, their quantum states overlap until the condensate becomes a single wave. Scientists have to release the trap to study the material. Unfortunately, even small perturbations from the outside world disrupt a Bose-Einstein condensate. That’s why we can only maintain them for a few milliseconds on Earth. Research conducted on the space station doesn’t have to contend with gravity, allowing them to isolate the condensate more effectively. Past efforts to do the same have relied on airplanes in freefall, and instruments dropped from great heights to lessen the effects of gravity.
In zero gravity, scientists were able to create a Bose-Einstein condensate from rubidium using shallower traps than on Earth. Even after dropping the trap, the material remained intact and in its condensate form for much longer than it would have on Earth. The team was able to take detailed measurements before the Bose-Einstein condensate dissolved. This could lead to incredible advances in our understanding of quantum mechanics and general relativity.
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