Mathematicians question dark energy in Einstein's equations of cosmic expansion

Mathematicians have argued that dark energy may not be needed to explain why the universe is speeding up. Researchers from UC Davis say the standard model of the universe contains a basic flaw that could allow cosmic expansion to accelerate under Einstein's original theory of gravity.

The team examined the mathematical framework that scientists use to describe cosmic expansion. They found it is inherently unstable. By studying instabilities in what are called Friedmann spacetimes, the researchers proposed alternative explanations for why space keeps stretching.

The work targets the Lambda-cold dark matter model, the widely used standard model of cosmology. This model relies on dark energy, a mysterious force assumed to drive the universe's acceleration. The researchers say their calculations point to weak points in that model.

Questions about our place in the universe

The findings also raise questions about the Copernican principle. This long-held idea holds that Earth does not occupy a special position in the universe. The researchers say their results make it worth asking whether our location is as ordinary as scientists have assumed.

The research is at an early stage, and it has not yet been tested against observations that cosmologists use to measure the universe. Other scientists have not yet said whether they accept the conclusions. The team has not said when further work will be published.

If confirmed, the work could lead to major changes in how scientists understand the cosmos. For now, it remains a theoretical proposal that challenges a central assumption of modern cosmology.