Photo: Large scale projection through the Illustris volume at z=0, centered on the most massive cluster, 15 Mpc/h deep. Shows dark matter density overlaid with the gas velocity field. Credit: Illustris Collaboration Astronomers have a pretty good idea how the universe began and the near-14 billion years of evolution after, but throwing all our knowledge behind one grand computer simulation has been hard. The task at hand is simply too huge for any one computer to handle.
Today, however, astronomers have announced the results of three months of computer number-crunching, combining 8,000 CPUs all running in parallel, modeling our evolving universe. If the same simulation was carried out on your office desktop computer, the simulation would take 2,000 years to recreate.
GALLERY: Violent Beauty of Our Evolving Universe
"Until now, no single simulation was able to reproduce the universe on both large and small scales simultaneously," said Mark Vogelsberger of the Harvard-Smithsonian Center for Astrophysics and lead scientist of the study.
Previous work has either focused on a tiny portion of cosmic volume or had been too low a resolution. This study, however, has created a cube 350 million light-years across and over 13 billion years of simulated time at an unprecedented resolution. This work has been published in the May 8 edition of the journal Nature.
In the model, the effects soon after the Big Bang are considered where the hot soup of primordial matter cools to form the first stars and young galaxies. Dark matter is also included in the calculations, which dominates the "cosmic web," anchoring clusters of galaxies at its gravitational nodes.
The effects of supernovae enriching the interstellar and intergalactic volume with increasingly heavier elements is also modeled, providing us with an insight as to the building blocks of other stars, planets and, eventually, the organic chemistry that is the foundation for life.
ANALYSIS: Building the Universe Inside a Supercomputer
The most striking thing about this virtual universe is its uncanny resemblance to observations made by today's observatories. The recreation of the array of galaxies we see deep in the furthest-most reaches of the universe form in strikingly familiar shapes and sizes.
The model only uses equations from theories constructed from decades (even centuries) of astronomical observations and allowed to evolve with time. The result is nothing short of breathtaking and it can be hard to distinguish the model from real observations.
The model, called Illustris, created a 3-D space filled with 12 billion pixels, all calculating the fundamental equations that govern normal (and dark) matter. The researchers can now zoom in on regions of interest to focus on different mechanisms as they unfold. When they kicked off the simulation 12 million simulated years after the Big Bang, some 41,000 galaxies condensed into numerous galactic cluster from the seemingly chaotic churning of matter.
GALLERY: The Supercomputer Supernova
"Illustris is like a time machine. We can go forward and backward in time. We can pause the simulation and zoom into a single galaxy or galaxy cluster to see what's really going on," added co-author Shy Genel, also of the CfA.
As noted in the Nature video accompanying the announcement of this study (below), there are some anomalies in the simulation that don't match our observations, but this is what science is all about; formulating hypotheses, testing theories and comparing them with observations. If something doesn't match up, there's something lacking in our understanding as to how the Cosmos works and astronomers will doggedly try to find answers to the mind-boggling questions the universe asks of us.
The Illustris team has released videos and images of the simulation in action.
Publication: Properties of galaxies reproduced by a hydrodynamic simulation, doi:10.1038/nature13316