An exotic material made in space could stimulate the hunting of gravitational waves

By launching a small bullet filled with atoms into space and launching it by laser, German scientists created for the first time a state of exotic matter, called Bose-Einstein condensate in space . Their discoveries could lay the foundation for a new method of gravitational wave search or ripples in space – time.

The Microgravity Matter-Wave Interferometry Experiment (MAIUS-1) launched on a sounding rocket at the Esrange Space Center in Sweden on January 23, 2017. The mission not only succeeded in creating the first condensate from Bose-Einstein based in the space, but researchers also performed more than 100 experiments with this sample during a 6-minute space flight. The results of the study were published today (October 17) in the journal Nature.

A Bose-Einstein condensate (BEC) is a state of matter that forms when a cloud of atoms is cooled to temperatures approaching absolute zero or 0. Kelvin, which equates to minus 459.67 degrees Fahrenheit (minus 273.15 degrees Celsius). When atoms become cold enough, they stop behaving like individual atoms and agglutinate while occupying the same state of energy, the weakest possible. In other words, it becomes impossible to distinguish the atoms and the block begins to behave as a single atom. [Infographic: How Gravitational Waves Work]

This phenomenon is the result of a principle of quantum mechanics known as wave-particle duality, in which light and matter exhibit both particle and β-ray properties. waves. The wavelength of a particle is directly related to its temperature. Higher energy particles have shorter wavelengths, while lower energy ones have longer wavelengths. By cooling a group of atoms until they all occupy the same state of low energy, their wavelengths extend over the entire atomic cloud and become identical.

To make atoms as cold as possible, scientists use a method called "laser cooling." "When a laser beam sends a photon (or particle of light) to an atom, the photon is absorbed by the atom and reduces its momentum. This is because these photons have their own momentum to begin with, and when an atom absorbs a photon, it also absorbs the momentum of the photon. During a frontal collision, the atom loses its momentum or slows down. The more the atoms move slowly, the lower the temperature will be

During the MAIUS mission, a sample of rubidium atoms was cooled to create the first BEC in the space. But the results of researchers' experiments with the BEC, which show that it is possible to measure gravitational waves in space more accurately than on Earth, may be even more exciting than this first time. historical.

The Discovery of Gravitational Attraction The Gravitational Observatory (LIGO), a ground-based laser interferometer in Louisiana, earned three physicists the Nobel Prize in 2017. The BECs in the space could help stimulate gravitational wave hunting. With spatial measurements, "we could in principle install a gravitational wave detector using atomic interferometry sensitive to frequencies other than LIGO," Maike Lachmann, researcher at the Leibniz University in Hannover, Germany , and one of the principal investigators for the MAIUS experiment, said Space.com.

Using a device called atomic interferometer, the researchers used laser beams to divide the material waves in half, then recombined them to create an interference pattern . When the atoms are in "free fall" or in a microgravity environment, the measurements "are sensitive to the forces of inertia, such as the gravitational field," said Lachmann. "The sensitivity varies quadratically with the time spent by the BEC in the interferometer," said Lachmann, adding that during this type of experiment on Earth, "the next problem is that the BEC s & # 39; 39, crushes the ground after a short time … in microgravity conditions, so you can observe it as long as you want. "

This new research" paves the way for quantum sensors in the space that could be used to conduct impossible experiments on Earth, "Liang Liu, a researcher from the Chinese Academy of Sciences of Shanghai who did not participate in the study, wrote in an article related to Nature News & Views. "Examples include the detection of gravitational waves in a frequency range that is generally not accessible, the detection of possible ultra-light dark matter particles, and the observation of the subtle effects badociated with the theory of general relativity. Einstein. Who knows what mysteries of the universe could be revealed by quantum sensors embedded in space? "

Before they could do this experiment in space, they first had to find a way to miniaturize the scientific equipment needed to produce BEC. "Normally, such a device occupies a whole laboratory room," said Stephan Seidel, co-author of the University of Hanover in a statement. "Designing a system so compact and robust that it can fly on a sounding rocket has been a major challenge for scientists and engineers." The probe rocket is only 2.5 meters tall and 0.5 meters long of diameter. .

Since the launch of the MAIUS mission, a similar experiment, known as the Cold Atomic Laboratory, has been sent to the International Space Station. The Cold Atom laboratory, which was launched at the space station in May, has since created the BECs by cooling a cloud of rubidium atoms, like the MAIUS mission.

Rubidium is "one of the easiest atomic species to cool down until Lachmann said," but of course it's possible to do it with other species. "For the next two missions MAIUS ( MAIUS-2 and -3), we will add potbadium-41 as the second species. "These missions will be launched between 2018 and 2019.

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