On April 24, 2026, a Chinese-led international team unveiled “HyperMillennium,” a cosmological simulation of unprecedented scale: a virtual cube 12 billion light-years on each side, populated by 4.2 trillion dark matter particles, tracing the universe’s structural evolution over 10 billion years.
Built using China’s domestically developed supercomputers and the self-optimized PhotoNs software, the project consumed over 100 million CPU core-hours and 10 million accelerator-card hours, generating approximately 13 petabytes of data — a volume equivalent to storing over 3,000 years of high-definition video.
By applying N-body numerical simulation techniques, researchers recreated how gravity sculpted the cosmic web from a nearly uniform early state into the filamentary structure observed today, enabling scientists to “rewind time” and test galaxy formation models against theoretical predictions.
The simulation’s high force resolution and temporal precision allow unprecedented study of rare, massive structures like superclusters and voids, while maintaining statistical robustness across the simulated volume — a balance previously unattainable at this scale.
Wang Qiao of the National Astronomical Observatories of the Chinese Academy of Sciences emphasized that the decade-long effort in algorithm optimization made efficient use of over 10,000 accelerator cards possible, turning a computational challenge into a practical research tool.
Mike Boylan-Kolchin of the University of Texas at Austin called the simulation a “computational marvel” that will help unlock secrets of dark energy and the early universe, noting its size and resolution set a new benchmark for future cosmological studies.
Volker Springel, director of the Max Planck Institute for Astrophysics in Germany, said he was “extremely impressed” by the achievement, stating it redefines the limits of numerical cosmology and enables high-precision tests of the standard cosmological model.
The simulation directly supports upcoming observational missions, including China’s Space Station Telescope and the European Space Agency’s Euclid mission, by providing theoretical templates for galaxy positions, brightness, and distribution patterns to compare against real survey data.
Beyond dark matter and energy research, the team noted the simulation’s potential to probe cosmological inflation and neutrino properties, areas where next-generation surveys of vast cosmic volumes may yield transformative insights.
This release marks a significant step in China’s emergence as a leader in computational cosmology, demonstrating international competitiveness in a field historically dominated by U.S. and European consortia.
Unlike earlier simulations that sacrificed either volume or resolution, HyperMillennium achieves both, allowing researchers to study rare cosmic phenomena without losing statistical significance — a critical advancement for testing hypotheses about dark energy’s role in cosmic acceleration.
The project underscores how specialized software and hardware co-design, rather than raw computing power alone, can overcome traditional barriers in scientific simulation, offering a model for future large-scale computational efforts in astrophysics and beyond.
How does HyperMillennium differ from previous cosmological simulations?
It combines a larger simulated volume (12 billion light-years per side) with higher particle count (4.2 trillion dark matter particles) and greater temporal accuracy than prior efforts, enabling detailed study of rare structures while maintaining statistical power.
What role did Chinese-developed technology play in this simulation?
The team used domestically built supercomputers and self-developed PhotoNs software, optimized over more than 10 years, to efficiently run the simulation using over 10,000 accelerator cards.
How will this simulation support real-world astronomical observations?
It generates synthetic galaxy catalogs with positions, brightness, and traits that can be directly compared to data from missions like China’s Space Station Telescope and ESA’s Euclid mission to test cosmological models.
What scientific questions could this simulation help answer?
It provides a tool to study dark matter and dark energy, test the standard cosmological model with high precision, and explore cosmic inflation and neutrino properties through comparison with future large-volume galaxy surveys.
