“Einstein’s gravitational theory, which is said to be the greatest single achievement of theoretical physics, resulted in beautiful relations connecting gravitational phenomena with the geometry of space; this was an exciting idea.” -Richard Feynman
For over a century after the publication of General Relativity, it was uncertain whether gravitational waves were real or not. It wasn’t until their first direct detection less than two years ago, by the LIGO scientific collaboration, that their existence was spectacularly confirmed. With the VIRGO detector in Italy coming online this year to complement the twin LIGO detectors, however, so much more became possible.
An actual position in space could be identified for the first time, enabling a possible correlation between the gravitational wave sky and the electromagnetic one. The three-dimensional polarization of a gravitational wave could be measured, and compared with the predictions of Einstein’s theory. And gravitational wave signals can be teased out earlier and measured to smaller amplitudes than ever before. Not only have we just seen our fourth gravitational wave event, we’ve seen it in all three detectors.