Cosmologists push back at the first moment after the big bang by simulating 4000 versions of the universe on a massive supercomputer.
The aim is to paint a picture of the immediate aftermath of the big bang, when the observable universe suddenly expanded 1 trillion trillion times in size in the smallest streak of a microsecond. By applying the method used for the simulations to true observations of the modern universe, researchers hope to gain an accurate understanding of what this inflationary period looked like.
“We are trying to do something like guess a baby picture of our universe from the latest picture,” study leader Masato Shirasaki, a cosmologist at the National Astronomical Observatory of Japan (NAOJ), wrote in an email to Live Science .
Plasters universe
The modern universe shows variations in density, with some spots rich in galaxies and others relatively barren. One promising hypothesis for this uneven distribution of visible matter is that at the time of the big bang, there were already quantum fluctuations, or random, temporary changes in energy, in the small, primordial universe, Shirasaki said.
When the universe expanded, these fluctuations would also have expanded with denser points extending into regions of greater density than their environment. Gravity would have interacted with these elongated filaments, causing galaxies to collapse along them.
But gravitational interactions are complex, and it is very challenging to try to flush back this inflationary period to understand what the universe would look like before it was. Cosmologists must essentially remove the gravitational fluctuations from the equation.
A clean start
The researchers developed a reconstruction method to do this. To find out if the reconstruction was accurate, they needed a way to test it. Therefore, they used NAOJ’s ATERUI II supercomputer to create 4000 versions of the universe, all with slightly different fluctuations in initial density. The researchers allowed these virtual universes to undergo their own virtual inflationes and then applied the reconstruction method to them to see if it could bring back their original starting points.
The results, published on January 4 in the journal Physical overview D, was promising.
“We find that a reconstruction method can reduce the gravitational effects on observed galaxies so that we can extract information about the initial states of our universe in an efficient manner,” Shirasaki said.
The reconstruction was previously applied to actual galaxy data, he added, but the new study shows that it could also work on the inflation period of the universe. The next step, Shirasaki said, is to apply the reconstruction to true observations of the cosmic web. These observations have already been made by a telescope in New Mexico as part of the Sloan Digital Sky Survey.
Originally published on Live Science