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By Amanda Greenwood
Associate News Editor
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Scientists have created a vast virtual version of the early universe, allowing researchers to follow the emergence of stars and galaxies across the first 2 billion years of cosmic history and compare the simulation's predictions with observations from modern telescopes.
The simulation, called Lumina, follows the evolution of dark matter, gas, stars and radiation across a volume of space about 1.6 billion light-years wide. Developed by researchers from institutions including the Massachusetts Institute of Technology (MIT) and the Center for Astrophysics | Harvard & Smithsonian, it begins roughly 45 million years after the Big Bang, during the period commonly known as the cosmic “dark ages,” when the universe had yet to be illuminated by the first stars and galaxies.
Rather than being an observation of the past, Lumina is a computer model that applies scientists' understanding of physics to calculate how the early universe could have evolved.
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The simulation contains around half a trillion computational elements, including dark matter particles and gas cells, allowing scientists to track how cosmic structures developed over time.
Scientists can use the simulation to study both large-scale cosmic structure and the formation of individual galaxies. According to MIT, it simulates a volume of the universe 100 times larger than past models. The simulation was run using the Frontier supercomputer at Oak Ridge National Laboratory in Tennessee.
From a Dark Universe to One Filled With Light
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After the Big Bang, the universe entered the cosmic “dark ages,” a period before the first stars and galaxies began producing light. As the first stars and galaxies started to appear, they produced radiation that stripped electrons from hydrogen atoms, a process known as reionization. As more hydrogen became ionized, light could travel more freely through space, helping transform the dark early universe into the transparent universe we see today.
Lumina reproduces this process, with its results indicating that hydrogen reionization was primarily driven by radiation from early stars and galaxies.
Astronomers can now compare Lumina's virtual universe with actual observations from telescopes such as NASA's James Webb Space Telescope, helping them test how well the simulation reflects the evolution of the early universe.
The James Webb Space Telescope allows astronomers to investigate "Cosmic Dawn," which happened roughly 50 million to one billion years after the Big Bang, when the first stars and galaxies formed. Webb has already identified galaxies dating further back in time than any previously known, including MoM-z14, which was confirmed in 2025 to have existed around 280 million years after the Big Bang.
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Observations from Webb are also providing direct evidence about reionization. In 2023, NASA reported that the telescope had identified transparent regions of gas around early galaxies, showing that stars in those galaxies were producing enough radiation to ionize the surrounding gas. As more gas became ionized, these transparent regions grew, gradually allowing energetic light to travel more freely through the universe.
The MIT team plans to make Lumina available to other scientists to enable further comparisons with observations.
Study co-author Xuejian Shen said the simulation's size creates enormous populations of virtual galaxies, allowing researchers to compare them with the large samples expected from upcoming astronomical surveys.
Such comparisons could provide an important test of scientists' understanding of the early universe. Agreement between observations and the simulation would support current models of how the first cosmic structures formed. Differences could reveal where those models need refinement.
Newsweek has contacted study co-authors Oliver Zier from the Center for Astrophysics and Shen from MIT for comment.
Newsweek’s reporters and editors used Martyn, our AI assistant, to produce this story. Learn more about Martyn here.
Contact Newsweek editors on this story: Ben Kelly and Rhian Morgan.
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