Doomsday Clock now at 90 seconds to Midnight — what does that mean?

Cover of the 1947 Bulletin of the Atomic Scientists issue, featuring the Doomsday Clock at “seven minutes to midnight”

The best way to tackle what has happened is to first give you a brief bit of background on what the Doomsday clock actually is. Who sets this, and what criteria they use to set it?

Brief History of the Clock Itself

The concept was started by a group of scientists who had been part of the Manhattan…