By Chad Hanna
Editor’s note: This article originally appeared on The Conversation.
The best thing about a day in my life on the lookout for gravitational waves is that I never know when it will begin.
Like many of my colleagues working for the Laser Interferometer Gravitational-Wave Observatory (LIGO), the morning of Monday, September 14, 2015 caught me completely off-guard. For years, we’ve been joking that Advanced LIGO would be so sensitive we might just detect one the very first day it turns on. In retrospect, it’s remarkable how close to reality that joke turned out to be.
LIGO is listening for gravitational waves – one of the last unproven predictions of Einstein’s theory of general relativity. In his view of the universe, space and time are fluid things that depend on an observer’s frame of reference. For example, time passes just a (very) little bit more slowly for those who work on the ground floor of an office building as compared to their peers on the 101st floor. Why? They’re deeper in Earth’s gravitational pull.