At a Glance
- A new review paper advocates for using numerical relativity simulations to solve fundamental questions about the universe’s origins and evolution.
- Traditional physics breaks down at the Big Bang singularity, where assumptions of a smooth and uniform universe prevent Einstein’s equations from being solved.
- Numerical relativity utilizes supercomputers to solve these complex equations without such assumptions, enabling the study of chaotic, strong-gravity environments.
- This method could help test theories on cosmic inflation, bouncing universes that undergo rebirths, and potential collisions with other universes.
- The authors aim to encourage collaboration between cosmologists and numerical relativists to accelerate progress on these major unsolved scientific problems.
A new review paper proposes that supercomputer simulations could be the key to answering one of science’s most profound questions: What happened before the Big Bang? In a paper published in Living Reviews in Relativity, a team of UK-based cosmologists and astrophysicists argues for the wider application of a powerful technique called numerical relativity. This method could allow scientists to probe the extreme conditions of the early universe, where the known laws of physics currently break down, potentially shedding light on cosmic origins, the multiverse, and the very nature of spacetime itself.
Traditionally, physicists have been stumped by the Big Bang because it represents a “singularity”—a point of infinite density and temperature where Einstein’s equations of general relativity cannot be solved with pen and paper. To make the math manageable for most cosmic scenarios, cosmologists assume the universe is largely the same in all directions, an approximation that works well today but is likely inaccurate for the chaotic birth of the cosmos. As researcher Eugene Lim explains, this limitation is like searching for lost keys only “around the lamppost” where there is light; numerical relativity allows scientists to “explore regions away from the lamppost.”
Numerical relativity is a computational approach that solves Einstein’s equations by breaking them into smaller, manageable pieces that a computer can process. First developed to simulate extreme events, such as the collision of two black holes—a problem that was finally solved in 2005 and helped predict the gravitational waves later detected by LIGO—the technique is perfectly suited for studying the universe’s first moments. By using simulations, researchers can abandon the simplifying assumptions of a uniform early universe and instead test a near-infinite variety of starting conditions, including those predicted by fundamental theories like string theory.
This computational tool opens the door to exploring some of the most speculative but exciting ideas in physics. Scientists could simulate “bouncing universes” that cycle through big bangs and crunches, search for the tell-tale gravitational wave signatures of hypothetical cosmic strings, or even look for “bruises” in our cosmos from a collision with another universe. The authors hope that their paper will bridge the gap between the fields of cosmology and numerical relativity, encouraging more experts to utilize these powerful simulations to tackle the universe’s greatest mysteries.
References
- Aurrekoetxea, J. C., Clough, K., & Lim, E. A. (2025). Cosmology using numerical relativity. Living Reviews in Relativity, 28(1), 5. https://doi.org/10.1007/s41114-025-00058-z
- Foundational Questions Institute. (2025, August 21). What happened before the Big Bang? Computational method may provide answers. Phys.Org; Foundational Questions Institute. https://phys.org/news/2025-08-big-method.html
