Uchuu: the biggest free virtual universe for anyone to explore

Dark matter distribution in an Uchuu image. The images show the dark matter halo of the largest galaxy cluster formed in the simulation at different magnifications. Credit: Tomoaki Ishiyama

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Forget about online games that promise a “whole world” to explore. An international team of researchers generated a whole universe virtual and made it available free on the cloud for everyone.

Uchuu (“Outer Space” in Japanese) is the largest and most realistic simulation of the universe to date. It consists of 2.1 trillion particles in a computational cube with an unprecedented distance of 9.63 billion light years across. For comparison, this is about three-quarters of the distance between Earth and the most distant observed galaxies. Uchuu will allow us to study the universe evolution in a level of size and detail unthinkable until now.

Uchuu focuses on the large-scale structures of the universe: mysterious halos of dark matter that control not only the formation of galaxies but also the fate of the entire universe. The scale of these structures varies from the largest galaxy clusters even the smallest galaxies. Individual stars and planets do not appear due to insufficient resolution, so don’t expect to find any alien civilizations in Uchuu.

Check out Uchuu’s YouTube preview below:

Time Machine

But one way in which Uchuu earns a lot compared to other virtual worlds is by mastering time. Uchuu simulates the evolution of matter over almost the entire 13.8 billion-year history of the universe, since the Big Bang until now. That’s 30 times longer than the time since animal life first crawled out of the seas on Earth.

Julia F. Ereza, a doctoral student at the Andalusian Institute of Astrophysics (IAA-CSIC, Spain) who uses Uchuu to study the large-scale structure of the universe, explained the importance of the time domain. “Uchuu is like a time machine,” she said. “We can go forward, backward and stop in time, we can ‘zoom in’ on a single galaxy or ‘shrink’ to visualize a whole cluster. We can see what is really happening every moment and everywhere in the universe from its earliest days to the present. It is an essential tool for studying the cosmos.”

Researchers from Japan, Spain, USA, Argentina, Australia, Chile, France and Italy created Uchuu using Aterui II, the world’s most powerful supercomputer dedicated to astronomy. Even with all this power, it still took a year to produce Uchuu. Tomoaki Ishiyama, an associate professor at the University of Chiba (Japan) who developed the code used to generate Uchuu, explained: “To produce Uchuu, we use (…) all 40,200 processors (CPU cores) available exclusively for 48 hours a month. Twenty million supercomputer hours were consumed and 3 petabytes of data were generated. It’s the equivalent of 894,784,853 images on a 12-megapixel cell phone.”

information compression

Before starting to worry about download time, the research team used high-performance computational techniques to compress information about the formation and evolution of dark matter halos in the Uchuu simulation into a catalog of 100 terabytes. This catalog is now available to everyone in the cloud in an easy-to-use format thanks to the skun6 computational infrastructure located at the IAA-CSIC, the RedIRIS group and the Centro Galego de Supercomputação (Cesga). Future data releases will include virtual galaxy catalogs and maps of gravitational lens.

Uchuu’s Big Data science products will help astronomers learn how to interpret the Big Data galaxy surveys expected in the coming years in installations such as the Subaru Telescope and the European Space Agency (ESA) Euclid space mission.