How Fast Is the Universe Expanding and Why Does It Matter?

Wednesday, 01 September 2021 5 p.m. — 6 p.m. MST

Online event

John Blakeslee (NSF's NOIRLab)
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Galaxies beyond our immediate cosmic neighborhood are all speeding away from us at an ever increasing rate, as if our Milky Way were some sort of cosmic pariah.  However, this perception is simply a consequence of the accelerating universe, not of some dreadful galactic faux pas on our part.  The rate at which galaxies increase their speed with increasing distance is known as the Hubble constant H0 (“H-nought”), and it tells us how fast the universe is expanding today. 

Astronomers have been trying to pin down the value of H0 for nearly a century, but distances are notoriously difficult to measure beyond the nearest galaxies. In this presentation, NOIRLab astronomer John Blakeslee will give an update on recent progress in measuring H0 and describe a puzzling disagreement between the best measurements and the predicted value based on what we know about the Big Bang. This mismatch may hint that the Universe is even more wonderful than we had imagined! Watch on our YouTube channel