For 13 years, the scientists of LIGO—the most ambitious, and expensive, project in the history of the National Science Foundation—had been waiting.
LIGO, the Laser Interferometer Gravitational-Wave Observatory, has been twenty-five years and more than half a billion dollars in the making. It involves 900 scientists and engineers, including many whose entire careers have been spent designing, building, and preparing to analyze data streaming in to LIGO. Their goal: To confirm, once and for all, Einstein’s century-old idea that gravity travels across space-time in the form of gravitational waves.
Well, they did.
This morning, the LIGO team announced that they had picked up gravitational waves from the collision of two orbiting black holes. “We have detected gravitational waves from a binary black hole system,” says Matthew Evans, …show more content…
Analyze the fringes, and you can tell how far each light wave traveled to cover the distance between the mirror and the sensor. More importantly, you can tell if that distance is changing over time. If a gravitational wave passes by, one arm of the observatory’s “L” should be stretched while the other gets squeezed, producing a telltale change in the fringe pattern.
What Kind of Noise Annoys an Interferometer?
But it gets more complicated. Everything from passing trucks to distant ocean waves can shake the mirrors, causing “noise” that muddies the measurements. That’s why LIGO isn’t just one machine, but a pair of facilities with identical-twin designs, one located in Livingston, Louisiana and the other Hanford, Washington. By putting almost 2,000 miles between the two instruments, physicists can discriminate between local jiggling, which will only be felt by one detector, and authentic cosmic gravitational waves, which should be felt by both.
ligo-Aerial5
LIGO's Hanford, Washington,
LIGO, the Laser Interferometer Gravitational-Wave Observatory, has been twenty-five years and more than half a billion dollars in the making. It involves 900 scientists and engineers, including many whose entire careers have been spent designing, building, and preparing to analyze data streaming in to LIGO. Their goal: To confirm, once and for all, Einstein’s century-old idea that gravity travels across space-time in the form of gravitational waves.
Well, they did.
This morning, the LIGO team announced that they had picked up gravitational waves from the collision of two orbiting black holes. “We have detected gravitational waves from a binary black hole system,” says Matthew Evans, …show more content…
Analyze the fringes, and you can tell how far each light wave traveled to cover the distance between the mirror and the sensor. More importantly, you can tell if that distance is changing over time. If a gravitational wave passes by, one arm of the observatory’s “L” should be stretched while the other gets squeezed, producing a telltale change in the fringe pattern.
What Kind of Noise Annoys an Interferometer?
But it gets more complicated. Everything from passing trucks to distant ocean waves can shake the mirrors, causing “noise” that muddies the measurements. That’s why LIGO isn’t just one machine, but a pair of facilities with identical-twin designs, one located in Livingston, Louisiana and the other Hanford, Washington. By putting almost 2,000 miles between the two instruments, physicists can discriminate between local jiggling, which will only be felt by one detector, and authentic cosmic gravitational waves, which should be felt by both.
ligo-Aerial5
LIGO's Hanford, Washington,