An early universe analog built in a laboratory in Germany

A team of researchers from the Universität Heidelberg built an early universe analog in their lab using cooled potassium atoms. In their article published in the magazine Nature, the group describes their simulator and how it can be used. Silke Weinfurtner, of the University of Nottingham, has published a News & Views article in the same journal issue outlining the team’s work in Germany.

Understanding what happened during the first few moments after the Big Bang is difficult due to the lack of evidence left behind. That leaves astrophysicists with nothing but theory to describe what might have happened. To make their theories credible, scientists have built models that theoretically represent the conditions described. In this new effort, the researchers used a novel approach to physical model in their lab to simulate conditions just after the Big Bang.

Starting with the theory that the Big Bang gave rise to a expanding universe, the researchers tried to create what they describe as a “quantum field simulator.” Since most theories suggest that it was likely that the early universe was very cold, almost absolute zero, the researchers created an environment that was very cold. They then added potassium atoms to represent the universe they were trying to simulate.

The atoms were cooled to just above absolute zero and slowed down with lasers, resulting in the formation of a Bose-Einstein condensate, a kind of superfluid. The researchers then used light from a specially designed projector to push the atoms into the desired arrangements. Under the arrangement, superfluid excitons, known as phonons, propagate in two directions.

By manipulating the propagation speed, the researchers were able to mimic the theory wave propagation in the early universe. They suggest that their superfluid behavior was somewhat similar to the physics that governed spacetime and particle production in those moments just after the Big Bang.

One of the first experiments conducted with the simulator involved mimicking the expansion of the early universe-the atoms in the superfluid moved in a ripple pattern in a manner similar to what the theory predicted when pairs of particles are created.

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