Lumina Simulation Models the Universe's First 2 Billion Years in Detail
Lumina, run on 15,000+ GPUs, is the largest radiation-hydrodynamics simulation of the early universe and the first to follow helium reionization live.
Researchers at the Center for Astrophysics | Harvard & Smithsonian have built “Lumina,” which they describe as the largest cosmological radiation-hydrodynamics simulation ever created. The work, led by Oliver Zier, is published in Monthly Notices of the Royal Astronomical Society, and the CfA announced it on October 27, 2026.
A radiation-hydrodynamics simulation follows how gas, dark matter and light act on one another as stars and galaxies form. Lumina tracks the first 2 billion years after the Big Bang. It shows how the earliest galaxies emerged and how they changed the vast regions of gas between them.
Two features set it apart. It covers more than 100 times the volume of previous comparable simulations, a cube roughly 1.5 billion light-years on each side, similar to the scale that today’s most powerful telescopes can survey. It is also the first to capture helium reionization (the stage when helium gas in intergalactic space was stripped of electrons by radiation) while letting the effects feed back into the evolving model right away. Co-author Aaron Smith of the University of Texas at Dallas said researchers can now follow hydrogen and helium reaching their modern state across a huge volume while still resolving the galaxies and other luminous objects driving the change.
The run needed more than 15,000 graphics processing units on Frontier, a supercomputer at Oak Ridge National Laboratory in Tennessee. That power let the team model a large volume without giving up the detail needed to study how galaxies, stars and black holes form.
Why it matters
Simulations turn theory into concrete predictions. When telescope data match them, confidence in the underlying physics grows. When they do not, there may be something new to learn. The team says comparing Lumina with observations from the James Webb Space Telescope, the Nancy Grace Roman Space Telescope and others will show whether current understanding of the universe’s governing laws holds up. For what Webb has found so far, see our guide to JWST discoveries, and for the broader picture, our cosmology guide.
What to watch next: the team plans to use Lumina to study how gas moves between galaxies, how radiation from the Big Bang shaped cosmic evolution, and how regions of intense star formation developed over time.
Primary source
This summary is based on Harvard & Smithsonian CfA and the peer-reviewed paper. Read the original for full details, data and caveats.
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