Four, three, two, one... Where does the countdown come from?

It has links to an early sci-fi film, atom-bomb tests, the space age. It’s now on apps, alerts, in clocks monitoring the climate crisis. And it’s still evolving

Four, three, two, one... Where does the countdown come from?
It has links to an early sci-fi film, atom-bomb tests, the space age. It’s now on apps, alerts, in clocks monitoring the climate crisis. And it’s still evolving