If you were out changing a tire in the rain or shovelling snow somewhere, you probably didn’t notice the European Space Agency’s Gaia spacecraft’s, “cosmic crisis,” so a quick update:
Best of all for cosmologists, Gaia’s new catalogue includes the special stars whose distances serve as yardsticks for measuring all farther cosmological distances. Because of this, the new data has swiftly sharpened the biggest conundrum in modern cosmology: the unexpectedly fast expansion of the universe, known as the Hubble tension.
The tension is this: The cosmos’s known ingredients and governing equations predict that it should currently be expanding at a rate of 67 kilometers per second per megaparsec — meaning we should see galaxies flying away from us 67 kilometers per second faster for each additional megaparsec of distance. Yet actual measurements consistently overshoot the mark. Galaxies are receding too quickly. The discrepancy thrillingly suggests that some unknown quickening agent may be afoot in the cosmos. aNatalie Wolchover, “Astronomers Get Their Wish, and a Cosmic Crisis Gets Worse” at Quanta
The skinny: Everything is the same as it was yesterday.