Fierce neutron star collision shows how fast the universe is expanding

CNET | 7/8/2019 | Jackson Ryan
pixieliliapixielilia (Posted by) Level 4
This illustration shows two neutron stars colliding, generating gravitational waves and a bright jet.

Gravitational waves are huge disturbances in the fabric of space-time, caused by immensely energetic astronomical events that ripple out across the universe. Although first predicted by physicist Albert Einstein in 1916, we've only very recently been able to "see" them. And now researchers are turning to gravitational waves to help reveal some of the lingering mysteries of the universe.

Mystery - Reason - Universe - Expansion - Galaxies

One such mystery is the reason behind the universe's expansion. If you look at galaxies from the Earth, in any direction, you'll find that they all seem to be moving away from us. Scientists aren't sure exactly why this is -- they suspect it has something to do with dark matter or dark energy -- but they have been doing their best to measure how fast the universe is expanding. That measurement is known as the Hubble constant and is one of the most important values for us to truly understand what's happening across the universe.

Right now, researchers have two ways to estimate the Hubble constant: They can study the background radiation leftover since the Big Bang or they can study huge stars ("Type 1a supernova") blowing up in the distant universe. As it stands, the Hubble constant they get using the two methods is vastly different.

Waves - Waves - Way - Hubble - Constant

That's where gravitational waves come in. Studying the waves opens up a third way to estimate the Hubble constant.

This simulation shows two neutron stars colliding as gravitational waves spill outward.

Paper - Monday - Nature - Team - Astronomers

In a paper published Monday in the journal Nature, an international team of astronomers used gravitational waves, generated by a merger of two incredibly dense neutron stars, to refine the measurement of the Hubble constant. The neutron star merger was first picked up in 2017 by gravitational wave detection efforts on Earth, known...
(Excerpt) Read more at: CNET
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