Gravitational waves directly measured: Big news from the world of physics and astronomy!

by John W. Weiss
Assistant Professor of Physics
Saint Martin's University

Gravity waves -- slight ripples in spacetime caused by any object with mass that accelerates -- were predicted 100 years ago by Albert Einstein based on his (now well-tested) Theory of General Relativity. Physicists have known that they exist for 30 years thanks to seeing their effects on the orbits of two pulsars (super-dense stellar remnants) orbiting each other. But this morning we awoke to the news that one of the gravity wave detecting teams has positively directly observed these ripples and it may well be the most exciting and significant physics discovery in most of our lifetimes.

Gravity waves are emitted by nearly every object in the universe, but most emit very weak, small waves. Even massive black holes, such as the ones detected, emit waves that make a person stretch or compress by one billionth of a trillionth of a meter. Such a small change is very challenging to detect -- to say the least -- but huge teams of scientists (the teams run in the hundreds) working hard to solve the myriad of technical hurdles has positively identified the signal of two merging black holes.

NASA visualization of  gravity waves produced by merging black holes.
Image by NASA, from Wikimedia Commons, public domain

Apart from the excitement of finally detecting Einstein's predicted waves, this discovery has physicists and astronomers buzzing thanks to the opportunities it will hopefully open up. Every time physicists have found new waves to look at signals from the universe (the telescope; other, invisible wavelengths like infrared; neutrinos; etc.), astronomers have quickly been able to learn exponentially more about our universe from the new perspectives offered. Gravity waves will hopefully similarly give us a fresh view of our universe and let us see things we were previously unable to observe.

The Northern Leg of the Laser Interferometer Gravitational-Wave Observatory on the Hanford Reservation in Benton County, WA which helped measure gravitational waves.
Image by Umptanum from Wikimedia Commons, CC BY-SA