A glut of gravitational waves

What they did: Researchers found 39 signals from gravitational waves sent out by colliding black holes and neutron stars picked up by the LIGO and Virgo detectors between April 1 and Oct 1, 2019.

• "The sharp increase in the number of detections was made possible by significant improvements to the instruments with respect to previous observation periods," according to the LIGO statement.

How it works: The two L-shaped LIGO detectors pick up gravitational waves by using a laser that runs down the length of each arm of the L.

• That laser bounces back to the bend in the L when it hits a mirror placed at each end.
• If both lasers get back to the middle at the same time, that means no gravitational wave has passed through, but if they're out of alignment, it could indicate a gravitational wave passed by, stretching the fabric of space and time as it did.