Inner Workings: How fast is the universe expanding? Clashing measurements may point to new physics

Astronomers picked up a burst of gravitational waves from the collision of two neutron stars, an event that astrophysicist Daniel Holz had been dreaming about for more than a decade. The neutron star merger, GW170817, gave Holz and his colleagues an entirely new way to measure how fast the universe is expanding. This method could settle a simmering dispute between the two established ways of measuring expansion, and it could mean rethinking the makeup of our universe-perhaps requiring new types of a subatomic particle or unexpected forms of dark matter or dark energy. Here, Ananthaswamy focuses on the aspects of the measurements develop to measure the expansion of the universe.