Washington (AP) – When two extremely dense neutron stars crashed together in a distant galaxy, astronomers struck scientific gold, confirming previously unproven theories, including some from Albert Einstein.
Scientists announced that after picking up two faint signals in mid-August, they were able to find the location of the long-ago crash and see the end of it play out. Measurements of the light and other energy that the crash produced helped them answer some cosmic questions.
Scientists, starting with Einstein, figured that when two neutron stars collide they would produce a gravitational wave, a ripple in the universe-wide fabric of space-time. Four other times that these waves were detected they were the result of merging black holes. This is the first time scientists observed one caused by a neutron star crash.
Where gold comes from
The Big Bang created light elements like hydrogen and helium. Supernovas created medium elements, up to iron. But what about the heavier ones like gold, platinum and uranium? Astronomers thought they came from two neutron stars colliding, and when they saw this crash they confirmed it. One astronomer described as a “giant train wreck that creates gold.” They estimate that this one event generated an amount of gold and platinum that outweighs the entire Earth by a factor of 10.
Gamma ray bursts are some of the most energetic and deadly pulses of radiation in the universe. Astronomers weren’t quite sure where short gamma ray bursts came from, but figured that a crash of neutron stars was a good bet. Watching this event confirmed the theory.
Astronomers know the universe is expanding, and they use a figure called the Hubble Constant to describe how fast. Two different ways scientists have of measuring this speed of expansion yields two numbers that are somewhat close to each other, but not quite the same. By measuring how far the gravitational wave had to travel, astronomers came up with another estimate that was between the earlier two, but it also comes with a large margin of error.
How fast do rays and waves go?
The crash showed that gravitational waves and gamma rays travel at nearly the speed of light – which is what Einstein’s General Relativity theory says. NASA astrophysicist Julie McEnery said: “Yet again, Einstein passes another test.”