An analogue of the early universe built in a laboratory in Germany

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

Understanding what happened during the first moments after the Big Bang is difficult due to the lack of evidence left behind. That leaves astrophysicists only theory to describe what could have happened. To give credence to their theories, scientists have built models that theoretically represent the conditions described. In this new effort, the researchers used a new approach to build a physical model in their lab to simulate conditions right after the Big Bang.

Starting from the theory that the Big Bang gave rise to an expanding universe, the researchers sought to create what they describe as a “quantum field simulator”. Since most theories suggest that the early universe was likely to be very cold, close to absolute zero, the researchers created a very cold environment. 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 using lasers, resulting in the formation of a Bose-Einstein condensate, a type of superfluid. The researchers then used light from a specially designed projector to nudge the atoms into the desired arrangements. In this configuration, superfluid excitons called phonons propagate in two directions.

By manipulating the speed of propagation, the researchers were able to mimic the theoretical propagation of waves in the early universe. They suggest that the behavior of their superfluid 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 using the simulator was to mimic the expansion of the early universe – superfluid atoms moved in a ripple pattern similar to what was predicted by the theory if pairs particles were created.

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