It is, if you except the powers of human memory, the closest thing we have to a time machine.
Scientists have created the first realistic model of the universe, capable of recreating 13 billion years of cosmic evolution. The simulation is called “Illustris,” and it renders the universe as a cube (350 million light-years on each side) with, its creators say, unprecedented resolution: The virtual universe uses 12 billion 3-D “pixels,” or resolution elements, to create its rendering. And that rendering includes both normal matter and dark matter.
The rendering, importantly, also includes elliptical and spiral galaxies—bodies that, because of numerical inaccuracies and incomplete physical models, we'd been unable to see with such detail in previous simulations of the universe. It also does a better job than previous renderings of modeling the feedback from star formation, supernova explosions, and supermassive black holes.
The model, reported today in the journal Nature, also takes us back to aaaaalmost the origin of the universe—just 12 million years after the Big Bang. And that’s where the time machine component comes into play. Since light travels at a fixed speed, Illustris gives astronomers the ability to correlate light with time (so, say, a galaxy that’s a billion light-years away will look to us like it did a billion years ago). That’s an important new capability. While the Hubble and similar space telescopes allow us to gaze on the early universe, Illustris lets us follow a single galaxy as it evolves over time.
With Illustris, paper co-author Shy Genel explains it, “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.”
Illustris has 41,000 galaxies in its simulation—a mix of spiral galaxies like our Milky Way along with elliptical galaxies. It represents five years of work on the part of the scientists from, among others, the MIT/Harvard-Smithsonian Center for Astrophysics and the Heidelberg Institute for Theoretical Studies in Germany. And it exists now in large part because computing technology has finally caught up with our aspirations for understanding the workings of the universe.
The calculations required to create the model took 3 full months of run time, using a total of 8,000 CPUs.
Had those calculations been done on on average desktop computer, the paper notes, the calculations would have taken more than 2,000 years to complete.