Jonah Kanner and Alan Weinstein in Nautilus:
At 2:40 a.m., my phone woke me up. At least one of us was always on shift, and that night in September of 2010, I had volunteered to respond to automated text messages from our alert system.
As a graduate student at the time, I (Jonah) had helped build the first quick-response alert software pipeline for two gravitational-wave observatories, called LIGO (Laser Interferometer Gravitational-wave Observatory) and Virgo. This system was designed to search for astrophysical signals in data as it arrived, to alert people who could check if a signal seemed valid, and share the message with astronomers around the world if needed. Every alert carried the possibility of a positive detection—humanity’s first direct observation of waves traveling through the fabric of spacetime, predicted by Einstein in 1916.
I got out of bed and made a sleepy-eyed walk to the small workstation we kept in our apartment. I didn’t know it, but the alert was the beginning of a professional and emotional rollercoaster. I logged into our event database and started browsing plots. I didn’t stay sleepy-eyed for very long. The plots showed an unusually loud signal. More dramatically, the waveform showed the “chirp” pattern that we were all hoping to see, something characteristic of the gravitational-wave emission from a pair of black holes spiraling together and then merging. The chirp was familiar to me from simulations, but nobody had ever seen one appear naturally. I plugged in headphones and jumped on to a conference call.
Nine of us—spread across the United States and Italy—began to talk the results over, wrestling with something too good to be true. Our hearts were racing. We needed to make a fast decision. If this dramatic signal was some kind of mistake, then there was no need for it to go further. After about 30 minutes of discussion, we agreed that the signal seemed valid, and pushed a button that spurred a collection of robotic telescopes to swing their gaze to the source location. Our log notes, usually dry, captured what we were all thinking that night: “Exciting!!!!! Very strong significant event …”