Gravitational waves were still a theory floating in space until last year, when LIGO (Laser Interferometer Gravitational-Wave Observatory) discovered two black holes had gone into a death spiral and collided 1.3 billion light-years away, sending tremors through space. It seemed like the be-all and end-all of astrophysics — until scientists realized it had just opened the portal to a new frontier.
While the Virgo interferometer has been around since 2007, the newly upgraded experiment will soon be joining forces with LIGO to take the detection of gravitational waves and the mind-blowing cosmic events that cause them (think neutron stars smashing into black holes) to an unprecedented level. Virgo technology and the power of some of the most advanced telescopes in existence will give the two LIGO detectors a boost when it comes to picking up on these space shivers and the far-out phenomena they issue from.
Gravitational waves are ironically small for such a momentous discovery. These ripples in space-time, which have been sci-fi fodder ever since Einstein predicted them in his Theory of General Relativity over a hundred years ago, originate in the enormous energy bursts released by black hole collisions. By the time they reach Earth, they end up even tinier than quarks. That's about one ten-thousandth the size of an atomic nucleus. Though smaller than subatomic particles, gravitational waves are still able to bend and stretch the fabric of space-time even if the effect is infinitesimal.
Detecting a tremor is notoriously tricky. LIGO's dual super-powered lasers let scientists know when a gravitational wave passes through our planet and alters space-time ('slightly' is an understatement) by a tell-tale wobble that results from its lasers moving in and out of phase with each other. Scientists are able to measure the size of the black holes involved in the collision, as well as how far away it happened, from the wobble's shape. This all sounds pretty straightforward until you realize that anything can affect these highly sensitive lasers. Everything on Earth that vibrates can trigger a false positive.
Enter Virgo. Multiple detectors are needed because just one could be set off by any random vibration. Adding Virgo to the LIGO experiment will trace gravitational waves to a much smaller piece of sky than before, determining where in the universe a massive crash occurred with greater accuracy. It will also buy more time to detect them when maintenance means another machine has to be temporarily shut down. Even something as monumental as a supernova would be difficult to confirm with just one active detector. Joining LIGO with Virgo and more upcoming detectors may not make time travel possible, but it could allow scientists to see things they may have never imagined.
"It's incredible that we might be able to see a merger of two neutron stars," said Julie McEnery, project scientist for NASA's Fermi Gamma-ray Space Telescope of just one phenomenon scientists could possibly witness in the future. "The range of physics we're going to be able to probe by having all of this information is extraordinary."