HARI SREENIVASAN: But first: 2016 has been a wild ride, one that we're not likely to forget anytime soon, much of it focused on politics, but many things happened in the world of science and technology as well. William Brangham starts our review for our weekly segment, the Leading Edge. WILLIAM BRANGHAM: Indeed, we wanted to look at some of the more remarkable discoveries and innovations, and setbacks that we saw in the scientific world this year. WILLIAM BRANGHAM: So, everyone is doing their year-end best-of list for 2016. The biggest one by far was a historic find announced in February, the detection of gravity waves.