The Universe May Not Be Expanding Equally In Every Direction, New Study Suggests

[Judi Lynn]

Alfredo Carpineti
By Alfredo Carpineti
09 APR 2020, 21:04

The cornerstone of our understanding of the cosmos is that the universe is expanding at the same rate in all directions. If so, this would make it "isotropic" as whichever direction we look, the universe is the same. If the universe is instead different in various directions, it would be called "anisotropic" – a finding that would force researchers to rethink a lot of cosmology. This idea is now being put forward in a new hotly debated study published in Astronomy & Astrophysics.

The team investigated the X-ray emissions of extremely hot gas present in 842 clusters of galaxies. The assumption is that clusters with similar temperatures at similar distances should appear equally bright in the sky, but the researchers did not observe this to be the case.

"We saw that clusters with the same properties, with similar temperatures, appeared to be less bright than what we would expect in one direction of the sky, and brighter than expected in another direction," co-author Thomas Reiprich, from the University of Bonn, said in a statement. "The difference was quite significant, around 30 percent. These differences are not random but have a clear pattern depending on the direction in which we observed in the sky."

Assuming that the difference observed is real, there are two possible scenarios for why: either something is wrong with how we have measured the properties of celestial objects using X-rays or the universe doesn't behave like we believe it to.

More:
https://www.iflscience.com/space/new-study-claims-that-the-universe-might-not-be-expanding-equally-in-every-direction/