Scientists have developed one of the most detailed simulations to date of how the universe evolved during its first two billion years, offering an unprecedented view of the cosmic web—the vast network of dark matter and glowing gas that underpins the structure of the cosmos. The simulation, named Lumina, was created using 15,000 graphics processing units on Frontier, one of the world’s fastest supercomputers, housed at the Oak Ridge Leadership Computing Facility in Tennessee.
Produced by researchers at the Center for Astrophysics, a collaboration between the Smithsonian Astrophysical Observatory and Harvard College Observatory, the model spans a cube of space 1.5 billion light years on each side, roughly 15,000 times wider than the Milky Way’s disk. The simulation visualizes the universe about 1.5 billion years after the Big Bang, showing bright filaments of dark matter intertwined with clouds of glowing gas.
The researchers have compared Lumina’s output with observations from the James Webb Space Telescope (JWST), which captures light from ancient galaxies that has traveled billions of years to reach Earth. These comparisons aim to test and refine astrophysical theories about the formation of galaxies and larger cosmic structures.
A video produced alongside the simulation cycles through different visual filters highlighting the density of dark matter and the temperature variations in gas clouds before focusing closely on individual galaxies embedded within the cosmic web. Still images generated from Lumina display regions of the early universe approximately 600 million light years across, revealing intricate dark matter filaments interlaced with luminous gas, colored to represent their speed.
Oliver Zier, lead author of the study published in the Monthly Notices of the Royal Astronomical Society, noted that the JWST has opened a new frontier in the study of the early universe. He emphasized the need to translate theoretical models into detailed predictions to interpret JWST’s observations accurately, describing the years of work culminating in the simulation as rewarding.
The simulation also captures the transition of the universe from an opaque fog of gas to large transparent bubbles of hydrogen and helium. This process, known as reionization, occurred when radiation stripped electrons from atoms, allowing starlight to penetrate the gas and spread freely. Aaron Smith of the University of Texas at Dallas, another study author, explained that Lumina enables the tracking of this transformation across vast cosmic volumes while resolving individual galaxies and luminous objects responsible for the changes.
Further data from the Nancy Grace Roman Space Telescope, launched in August aboard a SpaceX Falcon Heavy and scheduled to begin observations after reaching its destination a million miles from Earth in December, is expected to provide additional benchmarks. Researchers plan to use its findings alongside Lumina to enhance models of cosmic evolution and improve understanding of structure formation in the early universe.