In the basement of the Kirchhoff Institute for Physics in Germany, researchers are simulating the universe as it might have existed just after the Big Bang. They created a tabletop quantum field simulation that used magnets and lasers to control a sample of potassium-39 atoms kept near absolute zero. The equations are then used to transform the results at this small scale to investigate possible features of the early universe.
Research conducted so far has shown that it is possible to simulate universes with different curvatures. In a positively curved universe, moving in a straight line in any direction returns you to where you started. In a negatively curved universe, space is curved into a saddle shape. According to Marius Spahn, a doctoral student at the Kirchhoff Institute for Physics, the universe is currently flat or nearly flat. However, early in its existence, it may have been more positively or negatively curved.
around the curve
“If you have a very large sphere, such as the Earth, you can’t tell if it’s closed or infinitely open by looking at just a part of it.” Sabine, member of the Munich Center for Mathematics and Philosophy・Mr. Hossenfelder says: “It really becomes a philosophical question. All we know is what we get from the parts of the universe that we observe. Usually the way people express it is that I As far as we know, the curvature in this part of the universe is compatible with zero.”
Spahn was one of the authors of research papers such as:Quantum field simulator for dynamics in curved spacetimeHe collaborated with scientists from Belgium, Spain and Germany. The research team considered his three scenarios for the initial expansion of the universe: steady expansion, accelerating expansion, and decelerating expansion.
In the tabletop experiment, Spahn said, potassium-39 is placed inside a glass cell between large magnetic coils placed above and below it. These magnetic coils, along with several lasers, were used to control the behavior of the sample. According to some sources, the atoms were confined in thin layers that could be considered two-dimensional. press statement Graduated from Heidelberg University.
Spahn said that when potassium-39 is cooled to temperatures between 40 and 60 nanokelvins, it enters a quantum mechanical state known as a Bose-Einstein condensate. According to Ramon Szmuk, product manager at Quantum Machines, the Bose-Einstein condensate acts as a single megaparticle.
“Our Bose-Einstein condensate is an object that is completely governed by quantum mechanics because it operates at very, very low temperatures,” Spahn said. “The team is then looking for small perturbations. [the] Condensate. Therefore, you can imagine it as a small ripple of density fluctuations. These are governed by quantum mechanics. ”
“One run of our experiment obviously ends with taking a photo,” Spahn said. “So we shine light that resonates with the atomic transitions in potassium-39 and take absorption images of the cloud. And in the process, we typically destroy the condensed water. Where the atoms were, we You see less light. From there you can extract the density of the atoms. So the end result is always an image of the density distribution of the atoms. And from there you can perform statistical analysis to find out more information about the results. you can get.”
another world
Scientists have applied the cosmological equations and the Bose-Einstein condensation equations to draw conclusions about how the early universe behaved.
Spahn said the research team simulated positive curvature by increasing the density of potassium-39 from the center of the experimental setup outward. They simulated it by decreasing the negative curvature.
“We showed that we can simulate spatially curved and expanding spacetime in a Bose-Einstein condensate,” Spahn said. “This is necessary for a homogeneous, isotropic universe, and should be a natural assumption at large scales.”
For the past few years, scientists have been using quantum atomic systems to find similarities with complex systems in the universe, Schmuk said. This combines nuclear physics and astrophysics.
Nature, 2023. DOI: 10.1038/s41586-022-05313-9
cat friedrich A former mechanical engineer, he majored in applied mathematics, engineering, and physics at the University of Wisconsin-Madison. She earned a graduate degree focusing on science and environmental journalism and has edited seven news publications, two of which she co-founded. She is the editor-in-chief of the energy magazine Solar Today.
