Astrophysicists have detected Einstein’s gravitational waves! In a historic day for science, researchers at the LIGO experiment have directly detected gravitational waves emanating from a collision between a pair of black holes.
100 years after Einstein predicted gravitational waves but said we would never see them, scientists at the Laser Interferometer Gravitational-Wave Observatory (LIGO) experiment detected the elusive waves on September 14th, 2015. The discovery was confirmed at LIGO twin detector facilities in Livingston, Louisiana and Hanford, Washington, and was announced today (February 11) at a press conference.
The discovery promises to usher in a whole new area in gravitational wave astronomy. According to astrophysicists, the gravitational waves were from a collision between two black holes that happened 1.3 billion years ago. The black holes were about 29 and 36 times as massive as the Sun, scientists said.
“Our observation of gravitational waves accomplishes an ambitious goal set out over five decades ago to directly detect this elusive phenomenon and better understand the universe, and, fittingly, Einstein’s legacy on the 100th anniversary of his general theory of relativity,” said LIGO director David Reitze at the California Institute of Technology.
Einstein thought of space not as an empty void, but as a dynamic four dimensional fabric. If any accelerating bodies pass through the dynamic substance, it should create ripples in the fabric. In theory, small ripples wouldn’t be able to be detected here on Earth. Only the most massive objects, moving at incredible speeds (like a binary black hole), can create gravitational waves that can reach Earth.
“The description of this observation is beautifully described in the Einstein theory of general relativity formulated 100 years ago and comprises the first test of the theory in strong gravitation. It would have been wonderful to watch Einstein’s face had we been able to tell him,” said LIGO team member Rainer Weiss.
The twin scientific experiments at LIGO were looking to detect the subtle squishing and stretching of space in a wave fashion – the distinctive signature of the ripples Einstein had predicted. The observed effect of gravitational waves here on Earth is infinitesimally small, with scientists looking for oscillations of roughly the width of an atoms nucleus, or 1 part in 10^20.
LIGO uses an interferometer to detect the rhythmic changes in spacetime caused by gravitational waves. The instrument splits a single laser beam into two and sends them both off in an L shape, perpendicular to each other. After bouncing off mirrors, the waves that make up the lasers should be in perfect alignment as they return. Any change in distance that each light beam travels could be caused by gravitational waves.
Before this announcement LIGO had operated for over a decade without detecting gravitational waves.
Although much excitement surrounds the announcement, the discovery must stand the test of scrutiny from the scientific community. That will all begin when the full results of the discovery are published later this year in the peer-reviewed scientific journal Physical Review Letters.
But for now, LIGO scientists from the California Institute of Technology, the Massechusets Institute of Technology, as well as about 1000 contributors from 15 countries will celebrate this moment – and it’s another feather in the cap of Albert Einstein.