Pocket Universe

Tomoaki Ishiyama

Astronomy is a bit different from many sciences because you only have a sample size of 1. The cosmos contains everything we can observe, so astronomers can’t study multiple universes to see how our universe ticks. But they can create computer simulations of our universe. By tweaking different aspects of their simulation, astronomers can see how things such as dark matter and dark energy play a role in our universe. Now, if you are willing to spring for a fancy hard drive, you can keep one of these simulations in your pocket.

The Uchuu simulation is the largest and most detailed simulation of the universe ever made.¹ It contains 2.1 trillion “particles” in a space 9.6 billion light-years across. The simulation models the evolution of the universe across more than 13 billion years. It doesn’t focus on the formation of stars and planets but instead looks at the behavior of dark matter within an expanding universe. The detail of Uchuu is high enough that the team can identify everything from galaxy clusters to the dark matter halos of individual galaxies. Since dark matter makes up most of the matter in the universe, it is the main driver of galaxy formation and clustering.

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It takes a tremendous amount of computational power and storage to create such a detailed model. The team used over 40,000 computer cores and 20 million computer hours to generate their simulation, and it produced more than 3 Petabytes of data. That’s 3,000 Terabytes or 3 million Gigabytes for us mortals. Using high-density compression, however, the team was able to compress their results into a mere 100 Terabytes of storage.

That’s still a tremendous amount of data, but it can be stored on a single drive. For example, the Exadrive from Nimbus is a 100 Tb solid-state drive in a standard 3.5-inch form factor. Granted, it will set you back $40,000, but if you have that kind of change hiding between your couch cushions, why not use it to keep a universe in your pocket. Fortunately, if you don’t have that much spare change, you can access the data online. The Uchuu team has their raw data on skiesanduniverses.org, so you can explore their virtual universe all you want.

In addition to being a detailed cosmic simulation, the Uchuu simulation can be used by researchers working on scientific data mining. As large sky surveys and more simulations are created, the data will become so large data mining will play a crucial role in astronomical research. Until that data becomes available, data miners can hone their skills on a pocket universe.