One of the principles of science is that by repeating experiments we can learn some fundamental laws of nature. This is complicated when we are trying to learn about the secrets of the universe as a whole, though, because we only have one universe. And while we can't study multiverses, we might be able to do the next best thing.
Using supercomputers, physicists have created the largest-ever simulated universe. They created detailed catalogues of fake galaxies that can be compared with large-scale observations of real galaxies. This makes for a better understanding of the universe, as we can know the cosmological parameters with more precision.
Francisco Kitaura, lead author of the research, said in a statement: "We have developed the necessary techniques to generate thousands of simulated galaxy catalogues, reproducing the statistical properties of the observations." The research is published in Monthly Notices of the Royal Astronomical Society.
The simulated objects were created with the intention to compare them with the real objects seen in the Baryon Oscillation Spectroscopic Survey, or BOSS, which has scanned a large part of the sky and precisely measured the distance of more than 1 million galaxies up to 4.5 billion light-years away.
The distribution of galaxies in the universe is not random. Galaxies and clusters of galaxies are distributed in the so-called cosmic web. The galaxies follow the filaments of the web with large voids between groups of galaxies. The formations of the web happened right after the Big Bang, with its evolution being dictated by dark matter.
Dark matter is a mysterious form of matter that only interacts gravitationally. We can see the effect of it on galaxies, but we are yet to observe it in the lab. Constraining its properties was one of the challenges in preparing this simulation. Other challenges included having a realistic distribution of galaxies and including the correct mass of the galaxies, which strongly depends on their environments.
"Now we understand better the relation between the galaxy distribution and the underlying large-scale dark matter field," said Kitaura. "We will continue refining our methods to further understand the structures we observe in the universe."
A 2D map of galaxy distribution. On the left is real observation, and on the right is the simulated data. F. Kitaura