Physicists working at LIGO (the Laser Interferometer Gravitational-Wave Observatory) in Livingston, Louisiana, have “unequivocally” confirmed the existence of “gravitational waves” for the first time, according to a report from the Guardian. The announcement was made earlier today at a press conference in Washington by LIGO executive director David Reitze.
“We have detected gravitational waves. We did it.
“This was truly a scientific moonshot, and we did it, we landed on the moon.”
The announcement marks the culmination of a century of speculation and work, beginning with Albert Einstein’s theory on the existence of gravitational waves – the basis of his famous “Theory of General Relativity,” published in 1916 and described as the “geometric theory of gravitation.” It seems appropriate that this discovery comes in the year of the theory’s 100th anniversary.
It took 25 years to develop instrumentation sufficiently accurate to detect gravitational waves; they had to be able to, across a four km strip of mirror and laser, identify a distortion in spacetime a thousandth the diameter of one atomic nucleus across.
The physicists at LIGO had to wait for the collision of two black holes to finally be able to detect gravitational waves; the scientists “listened” in for 20 thousandths of a second, as the two massive black holes circled each other. At the beginning of the 20-millisecond window, the black holes were orbiting each other at a rate of 30 times per second. By the end, they had accelerated to 250 orbits per second, before finally colliding and merging.
As Scientific American notes, the collision was so strong, it produced a wave about 50 times that produced by all shining stars and galaxies in the universe combined, finally creating a gravity wave strong enough for LIGO to measure. For the record, that’s a volume of 4×1080 m3, or 4 followed by 80 zeroes.
The universe is a pretty big place.
It’s theorized that such events are actually incredibly common out in space, but this marks the first time that we’ve been able to observe one and verify the existence of gravitational waves at all. While suspected for a century, this discovery marks mankind’s first significant observational evidence of how gravity actually works. Even Einstein, who predicted them, was thoroughly uncertain of their existence.
Meanwhile, this discovery opens a new window on the universe, giving us an entirely new way to observe the cosmos which is unrestricted by traditional physics – if we can build instruments sufficiently complex to do so, and if we can figure out how to analyze the results.
Still, Reitze remains confident, saying, “I think we’re opening a window on the universe.”
Professor Neil Turok, the director of the Perimeter Institute for Theoretical Physics at Waterloo in Canada and a former research colleague of Prof Stephen Hawking, was even more enthusiastic, calling the discovery “the real deal, one of those breakthrough moments in science.”
“Just think of radio waves, when radio waves were discovered we learned to communicate with them. Mobile communication is entirely reliant on radio waves. For astronomy, radio observations have probably told us more than anything else about the structure of the universe. Now we have gravitational waves we are going to have a whole new picture of the universe, of the stuff that doesn’t emit light – dark matter, black holes.”
Turok also noted that this discovery means that we will, eventually, be able to observe the Big Bang directly, something previously impossible to do. Using our current technology, scientists can’t “look back” more than 400,000 years; beyond that, the universe was completely opaque to light. Gravitational wave observations will theoretically be able to “see” back the entire length of the universe’s almost 14-billion-year age, and we may one day be able to confirm the Big Bang with our own gravitational wave “eyes.”
[Photo by Andrew Harnik/AP]