We know that the universe is constantly expanding - it changes and creates new structures everyday, structures that then merge into each other and from others. Now, researchers from the University of Geneva have developed a code of numerical simulations that shed light on how the universe evolves, revealing more about the complex formation of its structures.
Using Einstein's equations, the team was able to integrate the rotations of space-time into their calculations and calculate the amplitude of gravitational waves, which were just confirmed to exist a few weeks ago.
Prior to these new simulations, scientists used numerical simulations of Newtonian gravitation to study the formation of large-scale cosmological structures. These codes are based on the idea that space itself is static as time goes on and conducts very precise simulations only if the matter in the universe moves slowly. However, at high speeds, these numerical codes can only make approximate calculations. Furthermore, they are incapable of describing fluctuations of dark energy, which makes up approximately 70 percent of the universe.
The new code, named "gevolution," is based on Einstein's theory of general relativity, which considers space-time as dynamic and constantly changing, contrary to the static space in Newtonian theory. The team's goal was to use this code to predict the amplitude and impact of gravitational waves and the rotation of space-time stimulated by the formation of cosmological structures.
In order to create gevolution, the team analyzed a cubic portion in space that consisted of 60 billion zones, each containing a portion of a galaxy, with the goal of determining how they move with respect to their neighbors. Using this data, they were able to study the motion of particles in space and calculate a metric using Einstein's equations, ultimately allowing them to discern the differences in the calculations gained from their model and those gained from Newtonian codes.
Knowing the differences between these two codes allows them to measure the effect of space-time and gravitational waves that are created by the formation of structures in the universe, marking the first time that a simulation code has taken these factors into account.
The team's new code will help scientists compare new models of the evolution of the universe with physical observations and may help us better understand the nature of dark energy.
The findings were published in the March 7 issue of Nature Physics.
