NASA | Expansion Rate: The Hubble Tension | NASA Hubble View

When the Hubble Space Telescope launched, one of its main goals was to measure the rate at which our universe is expanding.

That rate is called the “Hubble Constant” – named after the astronomer Edwin Hubble, who contributed to the discovery of the universe’s expansion. However, the expected value of the expansion rate is different depending on what equipment is being used to determine it.

In this video, Nobel Laureate Dr. Adam Riess explains this phenomenon known as “Hubble Tension,” and how important this mystery is to our understanding of the universe.