Standard image of the new scientist

The universe is expanding too quickly, and that could paraphrase cosmology

Different measurements of Hubble’s constant, the rate of space-time expansion, do not match – meaning we may have to look beyond Einstein’s theories to explain the universe

room


November 25, 2020

By Stuart Clark

At first it was a whisper. Now it has become a cry: something is wrong with our understanding of the cosmos. When we measure the speed at which the universe is expanding, we get different results depending on whether we extrapolate from the early universe or look at exploding stars in nearby galaxies. The discrepancy means that everything is falling apart faster than we expect.

The problem originally emerged a few years ago and the hope was that with closer observations it would go away. In fact, the latest measurements have made it impossible to ignore them. “It’s getting very serious,” says Edvard Mörtsell, cosmologist at Stockholm University in Sweden. “People must have really screwed it up for this to be in a sense not real.”

Cosmologists have been looking for answers. You have been playing around with the properties of dark energy and dark matter, these two familiar, but still mysterious, components of our standard model of cosmology. You have imagined all sorts of new exotic ingredients – all to no avail.

The conclusion could hardly be clearer. Our best model of the cosmos, a seemingly calm sailing ship, could be hidden under the waterline. This has led some researchers to propose the final step: get off the ship and build a new standard model from scratch based on a revised understanding of gravity. It is hardly the first such attempt. Now it comes with a twist – almost literally. By adding a quantum spin to Einstein’s theories of space and time, we can finally …