Historically, we’ve made important discoveries in the slower-style “time domain.” In the beginning, people who sat around obsessively watching the sky noticed that a few bright dots moved across the sky faster than other bright dots. Planets! Sometimes, fuzzy streaks appeared and then disappeared. Comets!
Using a device that blinked between telescope images of the same spot, like a (boring) celestial Viewmaster, Henrietta Leavitt discovered in 1912 a type of star whose varying brightness gives away cosmic distances. Later, these stars allowed Edwin Hubble to discover what a galaxy is, and that we live in one. Exploding supernovae led to the discovery of dark energy. Intelligence analysts found gamma-ray bursts while spying on Russian nuclear tests. The list goes on, but I will stop.
As technology has gotten better, the timespans we can discern have gotten shorter. Where we once tracked planets’ movements by hand to discover they were planets, we now measure second-to-second how the wind blows on Mars. Where we once would not have been able to see a 3-millisecond burst because we only took data in 30-second increments, we now see it when it occurs and command telescopes around the world to point to the same spot.
Today’s technology is not just letting us see the universe—it is letting us watch the universe happen. And it’s awe-inspiring.
We can see planets pass in front of stars. We can scrutinize the Sun’s magnetic loops as they tangle themselves up. We can shoot a radar at asteroids as they slide between us and the Moon. We can even watch asteroids crash into each other in other solar systems. A gas cloud’s close encounter with the black hole at the center of our galaxy? Astronomers tuned in to that daily like a sitcom.
But even the best astronomer doesn’t really understand what a billion years is. How could any of us? “An abstract, intellectual understanding of deep time comes easily enough—I know how many zeroes to place after the 10 when I mean billions,” said author Stephen J. Gould. “Getting it into the gut is quite another matter. Deep time is so alien that we can really only comprehend it as metaphor.”
Metaphors like the Cosmic Calendar of Cosmos fame, for instance. If you compress the history of the universe into a year, the Big Bang would have happened when the ball dropped on January 1, and the last Neanderthal would have died at 11:59 p.m. on December 31. It helps us see how long time in general is, and how short our time is.
But it’s also important to remember that with every tick of that metaphorical (and the literal) second-hand, the universe becomes a different place. And now with high-performance backends, we can actually find out what its growth and change look like. We can see how microseconds add up to seconds, seconds to minutes, minutes to hours. And maybe someday we will comprehend how hours become billions and billions of years.
Maybe to understand “deep time,” we first have to understand shallow time. After all, it’s the way we experience our own existence. As Annie Dillard said, “How we spend our days is, of course, how we spend our lives.” The same is true of the universe and its milliseconds.