Scientists at the Department of Energy’s Argonne National Laboratory have created the largest astrophysical simulation of the Universe ever. They used what was until recently the world’s most powerful supercomputer to simulate the Universe at an unprecedented scale. The simulation’s size corresponds to the largest surveys conducted by powerful telescopes and observatories.
The Frontier Supercomputer is located at the Oak Ridge National Laboratory in Tennessee. It’s the second-fasted supercomputer in the world, behind only El Capitan, which pulled ahead in November, 2024. Frontier is the world’s first exascale supercomputer, though El Capitan has joined the ranks of exascale supercomputing.
The new Frontier simulation is record-breaking and is now the largest simulation of the Universe ever conducted. Its exascale computing allows it to simulate a level of detail that was unreachable prior to its implementation. Exascale is so advanced that it’s difficult to fully exploit its capabilities without new programming paradigms.
Frontier is a significant leap in astrophysical simulations. It covers a volume of the Universe that’s 10 billion light years across. It incorporates detailed physics models for dark matter, dark energy, gas dynamics, star formation, and black hole growth. It should provide new insights into some of the fundamental processes in the Universe, such as how galaxies form and how the large-scale structure of the Universe evolves.
“There are two components in the universe: dark matter—which as far as we know, only interacts gravitationally—and conventional matter, or atomic matter.” said project lead Salman Habib, division director for Computational Sciences at Argonne.
“So, if we want to know what the universe is up to, we need to simulate both of these things: gravity as well as all the other physics including hot gas, and the formation of stars, black holes and galaxies,” he said. “The astrophysical ‘kitchen sink’ so to speak. These simulations are what we call cosmological hydrodynamics simulations.”
Cosmological hydrodynamics simulations combine cosmology with hydrodynamics and allow astronomers to examine the complex interrelationships between gravity and things like gas dynamics and stellar processes that have shaped and continue to shape our Universe. They can only be conducted with supercomputers because of the level of complexity and the vast number of numerical equations and calculations involved.
The sheer amount of energy needed for Frontier to perform these simulations is staggering. It consumes about 21 MW of electricity, enough to power about 15,000 single-family homes in the US. But the payoff is equally as impressive.
“For example, if we were to simulate a large chunk of the universe surveyed by one of the big telescopes such as the Rubin Observatory in Chile, you’re talking about looking at huge chunks of time — billions of years of expansion,” Habib said. “Until recently, we couldn’t even imagine doing such a large simulation like that except in the gravity-only approximation.”
“It’s not only the sheer size of the physical domain, which is necessary to make direct comparison to modern survey observations enabled by exascale computing,” said Bronson Messer, Oak Ridge Leadership Computing Facility director of science. “It’s also the added physical realism of including the baryons and all the other dynamic physics that makes this simulation a true tour de force for Frontier.”
Frontier simulates more than just the Universe. In June, researchers working with it achieved another milestone. They simulated a system of 466 billion atoms in a simulation of water. That was the largest system ever modeled and more than 400 times larger than its closest competition. Since water is a primary component of cells, Frontier is paving the way for an eventual simulation of a living cell.
Frontier promises to make advancements in multiple other areas as well, including nuclear fission and fusion and large-scale energy transmission systems. It’s also been used to generate a quantum molecular dynamics simulation that’s 1,000 times greater in size and speed than any of its predecessors. It also has applications in modelling diseases, developing new drugs, better batteries, better materials including concrete, and predicting and mitigating climate change.
Astrophysical/cosmological simulations like Frontier’s are powerful when they’re combined with observations. Scientists can use simulations to test theoretical models compared to observational data. Changing initial conditions and parameters in the simulations lets researchers see how different factors shape outcomes. It’s an iterative process that allows scientists to update their models by identifying discrepancies between observations and simulations.
Frontier’s huge simulation is just one example of how supercomputers and AI are taking on a larger role in astronomy and astrophysics. Modern astronomy generates massive amounts of data, and requires powerful tools to manage. Our theories of cosmology are based on larger and larger datasets that require massive computing power to simulate.
Frontier has already been superseded by El Capitan, another exascale supercomputer at the Lawrence Livermore National Laboratory (LLNL). However, El Capitan is focused on managing the nation’s nuclear stockpile according to the LLNL.