Though I rarely use an alarm clock, I awake nearly every morning at 6AM, no matter the time of year, or, weirdly, the time zone. It’s probably no coincidence that I have an affinity for precise timepieces, like the atomic clock unveiled this week so accurate that it will lose at most 1/10th of a second over the lifetime of the universe.
The predictability is comforting, yet time itself is hardly a constant. It moves faster in the mountains than at sea level, and when we are in motion instead of standing still. Beyond Earth, physicists have long given up the notion of a universal ‘present’, or even the surety of time’s linear progression: it is logically possible to travel through spacetime in a continuous trajectory toward the future and end up at the starting point, which is now in the past.