What the heck is the Doomsday Clock, and why did it just tick?

We’re two minutes to midnight. Again. Nuclear weapons test in 1952. U.S. Department of Energy The Doomsday Clock just ticked 30 seconds, bringing us at an uncomfy two-minutes-to-midnight for the first time since the Cold War. That sounds, well, not great. But what does it all mean? Is it art, or science? The Doomsday Clock is…