What’s the Expansion Speed?

Twenty years ago, scientists were shocked to realize that our universe is not only expanding, but that it’s expanding faster over time.

Pinning down the exact rate of expansion, called the Hubble constant after famed astronomer and University of Chicago alumnus Edwin Hubble, has been surprisingly difficult. Since then scientists have used two methods to calculate the value, and they spit out distressingly different results. But last year’s surprising capture of gravitational waves radiating from a neutron star collision offered a third way to calculate the Hubble constant.

That was only a single data point from one collision, but in a new paper published Oct. 17 in Nature, three University of Chicago scientists estimate that given how quickly researchers saw the first neutron star collision, they could have a very accurate measurement of the Hubble constant within five to ten years.

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