You know those video games that promise an entire world to explore? Astronomers have walked the extra mile and simulated a whole Universe freely available for everyone to explore!

By using ATERUI II, the world’s most powerful supercomputer dedicated to astronomy, researchers in Japan, Spain, USA, Argentina, Australia, Chile, France, and Italy have created Uchuu (“Outer Space” in Japanese).

Uchuu is the largest and most realistic simulation of the Universe to date. It gathers more than two trillion particles in a virtual cube. Its size is gigantic: almost 10 billion light-years to a side. That is about three-quarters the distance between Earth and the most distant observed galaxies!

Uchuu will allow astronomers to study the large-scale structure of the Universe and its evolution in such size and detail never seen until now. This super-simulation will give us a closer look on how dark matter controls the formation of galaxies and also the fate of the whole Universe itself. 

We won’t be able to see individual stars and planets (so we won’t find any alien civilisations for now with it) but we’ll be able to see galaxy structures, from the largest clusters to the smallest galaxies. 

Like a real-life time machine, Uchuu looks very far back and goes really deep in time: it simulates the evolution of matter almost since the Big Bang (13.8 billion years ago) to today. That is over 30 times longer than the time since animal life first crawled out of the seas on Earth!

This huge data catalogue “weighs” one hundred terabytes (for comparison, the Large Hadron Collider generates a thousand terabytes - or one petabyte - per day!) and is available on a cloud infrastructure called ‘skun6’, put together by Instituto de Astrofísica de Andalucía (IAA-CSIC), the RedIRIS group, and the Galician Supercomputing Center (CESGA).

Image: a snapshot of the distribution of dark matter in Uchuu. Here, we see the halo of dark matter of the largest galaxy cluster formed in the simulation in different sizes.

Credit: Tomoaki Ishiyama