The best known states of matter are solid, liquid and gaseous. But 99.9% of the observable matter in the universe is plasma: the fourth state of matter. Einstein predicted a fifth. And it was created in one of the coldest places in the known universe. The Cold Atom Lab (CAL) on board the International Space Station. There the fifth state of matter was created for the first time in space.
These are the Bose-Einstein condensates. They are gaseous atomic clouds that no longer behave like individual atoms. They start to behave like a collective and are often referred to as BECs. They were first predicted by Albert Einstein and Satyendra Nath Bose over 95 years ago. Scientists only observed them in the laboratory 25 years ago.
The general idea with a BEC is to inject atoms into an ultra-cold chamber to slow them down. Then a magnetic trap with an electrified coil is created in the chamber. It is used in conjunction with lasers and other tools to move atoms into a dense cloud. At this point, “the atoms are confused with each other”. David Aveline, physicist at NASA’s Jet Propulsion Laboratory, explains in a statement. He is the lead author of the new study.
To conduct experiments with a BEC, you must reject or release the magnetic trap. The cloud of overcrowded atoms will expand. This is useful because BECs need to be kept cold and gases tend to cool down as they expand. However, if the atoms in a BEC are too far apart, they will no longer behave like condensate. This is where the microgravity of Earth’s orbit comes into play.
What happens when you try to increase the volume on Earth? Aveline says that gravity simply pulls the atoms into the center of the BEC cloud. They go to the bottom of the trap until they spill and distort the condensate. The tools in CAL can hold atoms together in zero gravity. Even if the volume of the trap increases.
This creates a longer condensate. It enables scientists to study it longer than they could on Earth. This first demo lasted 1,118 seconds. The goal is to be able to capture the cloud of the fifth state of matter for up to 10 seconds.
The CAL experiment could one day enable BECs to form the basis for ultra-sensitive instruments. You would recognize weak signals from some of the most mysterious phenomena in the universe, such as gravitational waves and dark energy. From a practical point of view, Aveline believes that the team’s work could pave the way for better inertial sensors. “Applications range from accelerometers and seismometers to gyros,” he says.
