Three Decades of Space Telescope Observations Converge on a Precise Value for the Hubble Constant
Science history will record that the search for the expansion rate of the universe was the great Holy Grail of 20th-century cosmology. Without any observational evidence for space expanding, contracting, or standing still, we wouldn’t have a clue as to whether the universe was coming or going. Furthermore, we wouldn’t have any idea about its age either – or in fact, if the universe was eternal.
The first act of this revelation came when, a century ago, American astronomer Edwin Hubble discovered myriad galaxies outside of our home galaxy, the
“You are getting the most precise measure of the expansion rate for the universe from the gold standard of telescopes and cosmic mile markers.” — Nobel Laureate Adam Riess
For decades after Hubble, astronomers have toiled to nail down the expansion rate that would yield a true age for the universe. This required building a string of cosmic distance ladders assembled from sources that astronomers have a reasonable confidence in their intrinsic brightness. The brightest, and therefore farthest detectable milepost markers are Type Ia supernovae.
When the
The measurement is about eight times more precise than Hubble’s expected capability. But it’s become more than just refining a number to cosmologists. In the interim the mystery of dark energy pushing the universe apart was discovered. To compound things even further, the present expansion rate is different than it is expected to be as the universe appeared shortly after the big bang.
You think this would frustrate astronomers,…
Read More: Hubble Data Shows That “Something Weird” Is Going On