Fifth State of Matter Created on International Space Station

A fifth state of matter has been created in space, with scientists producing Bose-Einstein condensates onboard the International Space Station (ISS) in the Cold Atom Lab experiment.

A Bose-Einstein condensate is a state of matter that forms when a group of atoms clumps together when cooled to absolute zero (-459.67 F). In this state, the atoms have quantum properties and offer an insight into quantum mechanics. Producing them and studying them on Earth, however, is difficult because of gravity.

A Bose–Einstein condensate is a state of matter formed when a gas of bosons (such as rubidium atoms) is cooled down close to absolute zero. At this low temperature, the atoms become a single entity with quantum properties. Bose–Einstein condensates straddle the boundary between the microscopic world, governed by quantum mechanics, and the macroscopic world, governed by classical physics. As such, they may offer fundamental insights into quantum mechanics, but measuring them precisely is hampered by gravity. This force disrupts the magnetic fields required to hold them in a stable state to study. In space, with less gravity, this is far less of a problem.

"This actually is something I've been trying to do for about 23 years now," Robert Thompson, from the California Institute of Technology, told Newsweek in an email.

Thompson is one of the authors of a study published in Nature that describes the experiments on the ISS. The Cold Atom Lab uses several stages of cooling to produce the Bose–Einstein condensates. Lasers are used to cool atoms from room temperature down to around a millionth of a degree above absolute zero. From here, the atoms are moved into a magnetic trap, where the hottest ones are pulled off. The trap is then expanded, which cools the atoms further.

After generating the Bose-Einstein condensates they were able to compare how they behave in microgravity and how this compares to those produced on Earth. Findings showed the ISS Bose-Einstein condensates could be observed for over a second. This is far longer than on Earth, where they only last tens of milliseconds.

By being able to observe them for longer, scientists will be able to take better measurements of them. This will help with the study of ultracold atomic gasses, as well as our understanding of fundamental physics.

Thompson said more experiments are planned for the Cold Atom Lab. This includes creating "spherical 'bubble' condensates which can only be observed in space," as well as looking at the characteristics of collisions of quantum objects. Researchers will also be looking to test Einstein's theory of relativity to rule out certain candidates for dark matter—the invisible form of matter thought to make up around 25 percent of the universe—and dark energy, which is thought to drive the expansion of the universe.

"Several possible candidates for both dark matter and dark energy could potentially be observed with an atom interferometer," Thompson said. "One of our planned PI experiments...aims to search for signs of one particular candidate for dark energy, namely a chameleon field, which has a varying effective mass depending on the nearby energy density, and thus will experience a different acceleration if its near a massive object such as the edge of the vacuum chamber. This can be precisely measured by an atom interferometer, with sensitivity enhanced because microgravity allows the atoms to linger near the surface for an extended time."

He said the team has also recently observed the first atom interferometer in space. In the experiment, a laser pulse was used as a beam-splitter so "each individual atom is effectively in two places at once." Pulses are then used to recombine the atoms.

This, Thompson said, will form the basis of a new generation of precise quantum sensors. "This is the first matter-wave interferometer ever demonstrated in space, and heralds a future in which space-based quantum sensors become a widely used tool for scientists wishing to explore the universe," he said.

ISS
Illustration of the International Space Station. iStock