Gravitational Waves Could Help Us Solve a Big Cosmic Mystery About Neutron Stars

Now that we've confirmed (twice) that gravitational waves exist, astronomers want to use them as a tool to study one of the densest objects in our universe: neutron stars.

Scientists made history in February and again in June when they detected ripples of energy coming from two black holes merging. These "gravitational waves" were predicted by Albert Einstein 100 years ago, but this is the first time scientists had proof that they exist. 

Scientists suspect that colliding neutron stars also produce gravitational waves, and they say studying those waves will help us figure out what's going on inside the core of neutron stars, according to new research published in the Physical Review Letters.

Neutron stars are a big mystery

After a star runs out of fuel, collapses and explodes, sometimes a small patch of dense matter is left behind. That patch continues to condense and the intense gravity crushes the matter into a bundle of neutrons that become a neutron star.

That's neutron stars as we understand them today. But scientists want to figure out whether neutron stars really are just bundles of neutrons, or if some of the neutrons get crushed down into something even smaller called quarks. Under the neutron star's crippling gravity, the quarks might transform into a special type of matter called quark matter.

But we can't get inside a neutron star to find out. That's where gravitational waves come in. 

Gravitational waves can tell us "whether neutron stars are composed solely of ordinary atomic nuclei, or if they contain more exotic matter in the form of dense deconfined quark matter," according to physicist Aleksi Vuorinen.

Vuorinen and physicist Aleksi Kurkela have taken the first step by simulating what kind of gravitational waves colliding neutron stars might produce.

Now we'll have to wait until we detect some.