"Watching the video is like flying through the universe way faster than the speed of light and watching galaxies as they are assembling," said Paul Torrey, an astronomy graduate student at Harvard who helped develop the model known as the Illustris simulation.
Illustris is significant not just because it looks cool, but also because it is the first model to accurately predict the gas and metal content we see in the universe, as well as the variety of different types of galaxies we observe through our telescopes. It is so accurate, in fact, that a mock observation of galaxies from the Illustris model could pass for an image taken by the Hubble Ultra Deep Field Space Telescope. (See for yourself in a side-by-side comparison.)
To create the simulation the researchers considered the laws of physics, of course, but also how stars evolve, how gases cool, the explosive energy of supernovae, how heavy chemical elements get produced and the way gas accretes around super-massive black holes.
The model is so complex that it would take a regular desktop computer 2,000 years just to run the simulation once. To create the simulation you see above, the researchers used two super-computers -- one in France, the other in Germany.
At the start of the video you will see blue ephemera start to clump together and form a web-like structure. This is the cosmic web--a network of dark matter, drawn together by gravity. The pink areas are where the dark matter is the most dense.
As time goes on, the view switches from the blue and pinks of dark matter to the greens, reds and whites of the gas field. At about 4.9 billion years after the big bang you will start to see what look like explosions. This is feedback from super-massive black holes that scientists believe are at the center of nearly all the nearby galaxies.
"Black holes do swallow material, but when they are doing that they also release a lot of energy that can lead to large-scale outflows," said Torrey. "The presence of these black holes substantially alters galaxy formation."
The simulation does not start until 12 million years after the big bang, because before then the universe didn't have any structure to see, explained Torrey. And it spins so that viewers can get a better sense of the 3-D nature of the model.
The Illustris model is not an exact replica of the universe. It is smaller, for one--about 350 million light-years across. And though the 40,000 galaxies it created share the same properties as the ones in our universe, they are not in the exact same places as the galaxies we see in our telescopes.
The video at the top of this post is just one way of representing the data from the Illustris simulation. If you want to dig deeper, check out the website created by the Illustris team that gives both professional astronomers and curious lay people more access to the Illustris model. Especially fun is the Illustris explorer, which lets you zoom in on different parts of this mock universe.
"Our work here has only just begun," said Torrey. "Now that we have this model, our job is to understand it in as much detail as possible."