About one hundred years ago, Albert Einstein predicted the existence of gravitational waves. He developed his theory about the existence of such waves while he was working on his groundbreaking general theory of relativity.
For a long time, many people have eagerly anticipated the discovery of gravitational waves, knowing that if they were ever detected it would prove that Einstein must be right about relativity, too.
That day has now come — scientists have detected gravitational waves, or “ripples in space-time.” The waves were created by the merging of two black holes, just as Einstein predicted, as reported by CNN.
David Reitze, executive director of LIGO, the Laser Interferometer Gravitational-Wave Observatory, had the following to say to the press.
“We have detected gravitational waves. We did it.”
The scientists monitored two black holes, one with the mass of 29 suns, the other the equivalent of 36 suns. Each was about 50 kilometers, or 30 miles, in diameter.
The idea of gravitational waves emerged after Einstein realized that gravity deforms the space and time around itself. Objects move along the curves of spacetime, which itself is warped by mass, and gravity is the result of this.
The equations that Einstein developed to try to mathematically “show” this idea are so hard to solve that Einstein himself doubted his idea. The Economist had the following to say.
“Einstein was not happy with this idea. He would, himself, oscillate like a wave on the topic—rescinding and remaking his case, arguing for such waves and then, after redoing the sums, against them.”
Einstein could only solve his relativity equations by making some approximations and odd predictions. One of these predictions was that gravitational waves must exist.
“[Einstein made] an odd prediction: any accelerating mass should make ripples in spacetime.”
In September 2015, at the Advanced Laser Interferometer Gravitational-wave Observatory (LIGO), those waves were detected.
“[Gravitational waves] are thought to move through the universe, squeezing and stretching the fabric of space-time, but the oscillations are incredibly small and thus very difficult to detect, requiring incredibly sensitive instrumentation such as LIGO.”
Indirect proof of gravitational waves existence has been found over the years, but the waves themselves eluded researchers until the recent LIGO breakthrough.
Previously, the best scientists could manage was to measure radio emissions from pairs of dead stars called pulsars. The stars orbited one another, and scientists were able to measure how much the distance between them was shrinking as the stars broadcast gravitational waves into the cosmos.
The waves themselves proved elusive until the construction of LIGO. The new finding was based on a study not of stars but of two black holes that collided more than a billion years ago. LIGO estimates that the black holes collided about 1.3 billion years ago, at half the speed of light.
The gravitational waves that resulted from the collision of these black holes has been traveling through the universe for that whole time. Last year, the waves reached earth and were detected by the LIGO scientists.
The Guardian reports that more exciting discoveries could be on the way now thanks to the promising LIGO technology. First on their list is the possibility of finally detecting the “cosmic strings” predicted by physicists.
“[LIGO] could be used to observe phenomena that currently only exist in theory – cosmic strings. Theoretically these strings are many light years in length, moving at the speed of light, thinner than an atom but so massive just an inch would weigh 10 million billion tons.”
Gerry Gilmore, professor of experimental philosophy of the Institute of Astronomy at Cambridge, spoke about what an exciting field astronomy is as he speculated about how “strings” may finally reveal themselves. Gilmore reflected that there are many ways the entities could finally “show” themselves.
“Serendipity still rules astronomy, since we are very much a discovery-led science. Interestingly the source they discovered is not what one would have predicted, so that is a good start. Maybe [we will see] string-like defects thrashing around, left from Big Bang strings stretched by early inflation. Maybe higher dimensions popping in and out of existence.”
[AP Photo/Andrew Harnik]