Understanding dark energy is the number one issue in explaining the universe, according to Salman Habib, of the Laboratory’s Nuclear and Particle Physics, Astrophysics and Cosmology group.
“Because the universe is expanding and at the same time accelerating, either there is a huge gap in our understanding of physics, or there is a strange new form of matter that dominates the universe – ‘dark energy’ – making up about 70 percent of it,” said Habib. “In addition, there is five times more of an unknown ‘dark matter’ than there is ordinary matter in the universe, and we know it’s there from many different observations, most spectacularly, we’ve seen it bend light in pictures from the Hubble Space Telescope, but its origin is also not understood.”
Even though it’s looking at only a small segment of the “accessible” universe, Habib’s “Roadrunner Universe” model requires a petascale computer because, like the universe, it’s mind-bendingly large. The model’s basic unit is a particle with a mass of approximately one billion suns (in order to sample galaxies with masses of about a trillion suns), and it includes 64 billion and more of those particles.
The model is one of the largest simulations of the distribution of matter in the universe, and aims to look at galaxy-scale mass concentrations above and beyond quantities seen in state-of-the-art sky surveys.