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Move over Dr Who: We can travel the (virtual) universe too

An international team of researchers has generated an entire virtual universe and uploaded it to the “cloud”. They then made it freely available to anyone who wants to explore the cosmos without the pesky laws of physics (and economics) getting in their way.

Uchuu (meaning “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 that’s an unprecedented 9.63 billion light-years across – about three-quarters of the distance between Earth and the most distant observable galaxies. The simulation was unveiled in a study in Monthly Notices of the Royal Astronomical Society.

Uchuu is a virtual copy of the large-scale structure of the universe. It even contains the mysterious haloes of dark matter that control the formation of galaxies and the fate of the universe itself.      

It doesn’t re-generate individual planets and stars, however.


More reading: Explaining dark matter and black holes


The team of researchers, from Japan, Spain, the US, Argentina, Australia, Chile, France and Italy created Uchuu using ATERUI II, the world’s most powerful supercomputer dedicated to astronomy. But even with ATERUI II’s epic computational power, the simulated universe took a year to generate.

Tomoaki Ishiyama, an associate professor at Chiba University who developed the code used to generate Uchuu, explains: “To produce Uchuu we have used … all 40,200 processors (CPU cores) available exclusively for 48 hours each month. Twenty million supercomputer hours were consumed, and 3 Petabytes of data were generated, the equivalent of 894,784,853 pictures from a 12-megapixel cell phone.”

Time evolution of the number of haloes in each mass range as predicted by this simulation. The bar extending horizontally from each circle and triangle represents the range of the halo masses. The vertical axis is the number of haloes found in a cube about 9.6 billion light-years on each side. The gradient bars at the top of the figure represent the categories of objects found in haloes of that mass. The Uchuu simulation predicts that numerous haloes with masses comparable to the halo of our own galaxy were already formed about 13 billion years ago. Credit: Tomoaki Ishiyama

To circumvent the problem of download time, the team used high-performance computational techniques to compress the information on the formation and evolution of dark matter haloes into a 100-terabyte catalogue. This catalogue is now available to everyone on the cloud in an easy-to-use format thanks to the computational infrastructure skun6 located at the Instituto de Astrofísica de Andalucía (IAA-CSIC), the RedIRIS group, and the Galician Supercomputing Center (CESGA). Future data releases will include catalogues of virtual galaxies and gravitational lensing maps.

It’s not just a flight of fancy. Uchuu will help astronomers learn how to interpret big data galaxy surveys from facilities like the Subaru Telescope and the ESA Euclid space mission.

Uchuu also has a time dimension; it simulates the evolution of matter over the entire 13.8-billion-year history of the universe. This makes it a powerful tool for understanding how the universe came to be, and how it may evolve into the future.

Julia F. Ereza, a PhD student at IAA-CSIC, explains the importance of the time domain: “Uchuu is like a time machine: we can go forward, backward and stop in time, we can ”zoom in” on a single galaxy or ”zoom out” to visualize a whole cluster, we can see what is really happening at every instant and in every place of the universe from its earliest days to the present, being an essential tool to study the cosmos.”