How fast is Universe expanding? Exploding star raises new questions

How did we get here? Where are we going? And how long will it take? These questions are as old as humanity itself, and, if they’ve already been asked by other species elsewhere in the Universe, potentially very much older than that.

There are also some of the fundamental questions we are trying to answer in the study of the Universe, called cosmology. One cosmological conundrum is how fast the Universe is expanding, which is measured by a number called the Hubble constant. And there is quite a bit of tension around it.

In two new papers led by my colleague Patrick Kelly at the University of Minnesota, we have successfully used a new technique – involving light from an exploding star that arrived at Earth via multiple winding routes through the expanding Universe – to measure the Hubble constant. The papers are published in Science and The Astrophysical Journal.