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Meet Mira, the Supercomputer That Makes Universes
From an interview in the September Atlantic:
http://www.kintera.org/TR.asp?a=9rKNL2PIJeKIJZOQG&s=glIYIjOVLeKYJcNRLsH&m=iuLUL6NNIcKOKgJ
In October, the world's third fastest supercomputer, Mira, is scheduled to run the largest, most complex universe simulation ever attempted. The simulation will cram more than 12 billion years worth of cosmic evolution into just two weeks, tracking trillions of particles as they slowly coalesce into the web-like structure that defines our universe on a large scale. Cosmic simulations have been around for decades, but the technology needed to run a trillion-particle simulation only recently became available.
snip
Salman Habib is a senior physicist at the Argonne National Laboratory and the leader of the research team working with Mira to create simulations of the universe. Last week, I talked to Habib about cosmology, supercomputing, and what Mira might tell us about the enormous cosmic web we find ourselves in.
snip
Salman Habib is a senior physicist at the Argonne National Laboratory and the leader of the research team working with Mira to create simulations of the universe. Last week, I talked to Habib about cosmology, supercomputing, and what Mira might tell us about the enormous cosmic web we find ourselves in.
A response to one of the interviewer's questions:
Habib: Our primary interest is large-scale structure formation throughout the universe and so we try to begin our simulations well after the Big Bang, and even well after the microwave background era. Let me explain why. We're not sure how to simulate the very beginning of the universe because the physics are very complicated and partially unknown, and even if we could, the early universe is structurally homogeneous relative to the complexity that we see now, so you don't need a supercomputer to simulate it. Later on, at the time of the microwave background radiation, we have a much better idea about what's going on. WMAP and Planck have given us a really clear picture of what the universe looked like at that time, but even then the universe is still very homogeneous -- its density perturbations are something like one part in a hundred thousand. With that kind of homogeneity, you can still do the calculations and modeling without a supercomputer. But if you fast forward to the point where the universe is about a million times denser than it is now, that's when things get so complicated that you want to hand over the calculations to a supercomputer.
Now the trillions of particles we're talking about aren't supposed to be actual physical particles like protons or neutrons or whatever. Because these trillions of particles are meant to represent the entire universe, they are extremely massive, something in the range of a billion suns. We know the gravitational mechanics of how these particles interact, and so we evolve them forward to see what kind of densities and structure they produce, both as a result of gravity and the expansion of the universe. So, that's essentially what the simulation does: it takes an initial condition and moves it forward to the present to see if our ideas about structure formation in the universe are correct.
Now the trillions of particles we're talking about aren't supposed to be actual physical particles like protons or neutrons or whatever. Because these trillions of particles are meant to represent the entire universe, they are extremely massive, something in the range of a billion suns. We know the gravitational mechanics of how these particles interact, and so we evolve them forward to see what kind of densities and structure they produce, both as a result of gravity and the expansion of the universe. So, that's essentially what the simulation does: it takes an initial condition and moves it forward to the present to see if our ideas about structure formation in the universe are correct.
Here's where Mira lives -
6 replies
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The next contest's theme is " a photo taken outside, within 100 paces from your home".
I had no idea where I live would be exposed so early.
Dang.
From the upper floor of the "high rise" rectangular building in the foreground you can see the Chicago skyline in the distance... I once got myself locked outside on the roof there late at night in December while our APS experiment was running and I was taking a break. Fortunately I was able to MacGuyver my way back into the building before I got too cold (I had no cell phone to call for help and there weren't many people around).
MIRA is evidently in Building 240, which houses math & computer science
