In a recent press release containing new images captured by the Hubble Space Telescope, the National Aeronautic and Space Administration said that something weird was going on in outer space. No, really, that’s what they said:
In recent years, thanks to data from Hubble and other telescopes, astronomers found another twist: a discrepancy between the expansion rate as measured in the local universe compared to independent observations from right after the big bang, which predict a different expansion value.
The cause of this discrepancy remains a mystery. But Hubble data, encompassing a variety of cosmic objects that serve as distance markers, support the idea that something weird is going on, possibly involving brand new physics.
Since the discovery of dark energy in the 90s, researchers have been able to account for the total sum of matter in the cosmos. This data, with help from the powerful Hubble Space Telescope, has helped scientists to track the expansion rate of the universe. Which is pretty cool! Except now — as this press release explains — something is off. Because their calculations have been right, until they weren’t.
The expansion rate of the universe was predicted to be slower than what Hubble actually sees. By combining the Standard Cosmological Model of the Universe and measurements by the European Space Agency’s Planck mission (which observed the relic cosmic microwave background from 13.8 billion years ago), astronomers predict a lower value for the Hubble constant: 67.5 plus or minus 0.5 kilometers per second per megaparsec, compared to the SH0ES [Supernova, H0] team’s estimate of 73.
Given the large Hubble sample size, there is only a one-in-a-million chance astronomers are wrong due to an unlucky draw, said Riess, a common threshold for taking a problem seriously in physics.
So it’s not quite Lovecraftian cosmic weird, but it’s still pretty weird.
Hubble Reaches New Milestone in Mystery of Universe’s Expansion Rate [NASA]