Gravitational waves hold answers to universal expansion

Boston, July 12: Gravitational waves emitted by a rare system — a hugely energetic pairing of a spiralling black hole and a neutron star — can be used to determine the Hubble constant, which describes the rate at which the universe is expanding, scientists say.

Since it first exploded into existence 13.8 billion years ago, the universe has been expanding, dragging along with it hundreds of billions of galaxies and stars, much like raisins in a rapidly rising dough.

Astronomers have pointed telescopes to certain stars and other cosmic sources to measure their distance from Earth and how fast they are moving away from us — two parameters that are essential to estimating the Hubble constant, a unit of measurement that describes the rate at which the universe is expanding.

However, the most precise efforts have landed on very different values of the Hubble constant.

This information could shed light on the universe's origins, as well as its fate, and whether the cosmos will expand indefinitely.

According to a study, the flash of light would give scientists an estimate of the system's velocity.

Scientists have proposed a more accurate way to measure the Hubble constant, using gravitational waves emitted by a relatively rare system: a black hole- neutron star binary.