Cosmology May Be In For a Shakeup

We've known for many years that the universe is exapnding. The speed of the expansion is called the Hubble constant and there are two ways of measuring it: looking at the cosmic background radiation (the embers of the Big Bang) or measuring the distance to a type of stars called Cepheid variables. The two numbers should agree, but they don't.

This is causing some consternation among cosmologists, the astronomers who study the large scale universe. The discrepancy is now several percent, which is many times observational error. So it means that there's something basic that they're missing.

"The Hubble tension between the early and late Universe may be the most exciting development in cosmology in decades," said astrophysicist Adam Riess of the Space Telescope Science Institute (STScI) and Johns Hopkins University.

"This mismatch has been growing and has now reached a point that is really impossible to dismiss as a fluke. This disparity could not plausibly occur by chance."

Which means that there's something out there that we've missed. As a study last year deriving the Hubble Constant using black holes proposed, the acceleration could be the result of an increase in the density of dark energy.

I'll be watching developments with some interest.