Researchers at MIT, Harvard and partner institutions have presented Lumina, a simulation of the universe’s first two billion years. MIT announced the work on October 26, alongside publication in Monthly Notices of the Royal Astronomical Society. The model offers astronomers a way to test how early galaxies transformed the gas around them.
According to the paper, Lumina follows dark matter, gas and radiation in a cube measuring 500 megaparsecs on each side in coordinates that account for cosmic expansion. The Smithsonian describes its volume as more than 100 times that of earlier comparable simulations. Its significance is the combination of a vast region with detail sufficient to study developing galaxies.
The team ran the calculations on the Frontier supercomputer at Oak Ridge National Laboratory in Tennessee. MIT reports that the simulation begins about 45 million years after the Big Bang. It follows matter gathering into structures while tracking how radiation travels through gas, linking galaxy formation to changes in the surrounding universe.
A central focus is reionization, when radiation removes electrons from atoms or ions. The research connects hydrogen reionization mainly to early stars and galaxies, while energetic radiation from actively feeding black holes drives the later removal of the remaining electron from singly ionized helium. Modelling both stages helps researchers examine how cosmic gas changes and heats up.
The Smithsonian says comparisons with telescope observations will test the model’s predictions. These are simulated histories, rather than direct images of the ancient universe. The paper notes limitations, including the absence of modelling for the first, metal-free stellar population. Future work will explore gas flows and cosmic structure, checking where the calculations agree with observations and where they need refinement.
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