Smithsonian scientists just recreated the first 2 billion years of the Universe

Scientists at the Center for Astrophysics | Harvard & Smithsonian have created Lumina, one of the largest and most detailed simulations of the early universe ever developed. The simulation reconstructs the first 2 billion years after the Big Bang by modeling interactions between ordinary matter, dark matter, and radiation. The research, published in Monthly Notices of the Royal Astronomical Society, aims to help astronomers interpret observations from the James Webb Space Telescope and Nancy Roman Space Telescope.

Lumina is the largest cosmological radiation hydrodynamics simulation ever produced. Its virtual universe spans a cube approximately 1.5 billion light-years on each side, modeling a volume of space more than 100 times larger than earlier comparable projects. The simulation tracks helium reionization, a process in which radiation strips electrons from helium atoms, while simultaneously accounting for how it affects the surrounding universe. This marks the first time a simulation of this kind follows that transformation across such an enormous volume while resolving individual galaxies.

Creating Lumina required more than 15,000 graphics processing units on Frontier, one of the world's fastest supercomputers housed at Oak Ridge National Laboratory in Tennessee. The processing power enabled researchers to simulate an exceptionally large region of the early universe while maintaining fine detail needed to investigate individual galaxies, stars, black holes, and other structures.

"With JWST, the early universe has become an exciting new frontier in astrophysics," said Oliver Zier, lead author and ITC Fellow at the Center for Astrophysics. "To understand what we are seeing with this telescope, we need to translate our theories into detailed predictions."

Scientists plan to compare Lumina's predictions with telescope observations to evaluate how well existing theories explain cosmic evolution. Unexpected differences between the simulated cosmos and actual observations could reveal where current theories need refinement.