An early universe analogue built in a laboratory in Germany

A team of researchers at the University of Heidelberg built an isotope of an early universe in their lab using cooled potassium atoms. In their paper published in the magazine temper nature, the group describes their simulator and how it can be used. Silke Weinfurtner, with the University of Nottingham, published an article in News & Views in the same issue of the magazine summarizing the work the team has done in Germany.

It is difficult to understand what happened during the first few moments after the Big Bang due to the lack of evidence behind it. This leaves astrophysicists with nothing but theory to describe what might happen. To give credence to their theories, scientists built models that theoretically represent the described conditions. In this new effort, the researchers used a novel approach to build a physical model in their lab to simulate conditions just after the Big Bang.

Starting with the theory that the Big Bang led to the expansion of the universe, researchers have sought to create what they describe as a “quantum field simulation.” Since most theories suggest that the early universe was likely to be extremely cold, close to absolute zero, the researchers created an extremely cold environment. Then they 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 a laser, creating a Bose-Einstein condensate – a type of superfluid. The researchers then used light from a specially designed projector to push the atoms into the desired arrangements. Under the setting, superfluid excitons known as phonons propagate in two directions.

By manipulating the velocity of propagation, the researchers were able to simulate the supposed propagation of waves in the early universe. They suggest that their superfluid’s behavior was somewhat similar to the physics that govern spacetime and particle production in those moments immediately following the Big Bang.

One of the first experiments with the simulator involved simulating the expansion of the early universe — atoms in the superfluid moved in a ripple pattern in ways similar to what theory predicted if pairs of particles were to form.

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