Go to the beach and sit down on the sand—or if no beach is nearby, find a child’s sandbox. Pick up a handful of sand and bring it up to your face so you can see the individual grains; let them trickle through your fingers. Look up and down the beach at all the sand and imagine trying to count every last tiny mote of it.
Then, come evening, lie on your back and stare up at the black sky dusted with gleaming pinpricks and realize the unfathomable vastness of the universe: there are more stars in that sky above your head than there are grains of sand on all the beaches and in all the sandboxes in all the world.
Our home galaxy, the Milky Way, contains at least 200 billion stars. If but five percent of those stars have planets, that means that 10 billion solar systems exist beyond our own. But given that current technology would not allow us to find solar systems like our own, it is likely that the percentage of stars with planets is far, far higher. And yet, that’s just the stars within one galaxy. The observable universe contains at least 100 billion galaxies averaging the size of our own Milky Way.
What does all that mean? That the number of planets in the universe is probably far vaster than the number of stars. And even odder to think about: if even only one percent of those planets are capable of harboring life, and if only one percent of those have intelligent beings on them who can look up at their night skies and wonder about what they are seeing—the number of civilizations in the universe will be uncountable billions.
There are 86,400 seconds in a day. There are about 31and a half million seconds in a year (if you figure at year at 365.25 days). If you were to start taking a photograph of each star in just our galaxy, and took a photograph once every second, twenty-four hours a day, seven days a week, with no time off for sleeping or anything else, it would take you over thirty-one years just to photograph the first one billion stars. To get photos of all the stars in the Milky Way Galaxy, given that there are 200 billion of them, would take you over six thousand years: the length of all recorded human history. Then you’d still have another hundred billion galaxies to go, just in the visible universe, each with its 200 billion stars.
One can devote an entire lifetime to the study of a single subject, for instance Russian literature. And one could specialize further and devote oneself to the work of just one Russian author, say Dostoyevsky. Or maybe you’d like to devote yourself to the study of Russian history, perhaps twentieth century Russian history (I took a year long course in that in college as an undergraduate). Most of us in high school or college took a course in World Civilization, which covered the entire history of our planet in a single year. Not much detail in a class like that. Now imagine trying to cram the history of multiple civilizations into your brain: the billions that maybe lie scattered across our skies.
I marveled at the grains of sand trickling through my fingers one sunny summer day not long ago, while the waves were roaring in the background. And I couldn’t help imagining how they represented worlds scattered across endless oceans of night, each with waves and sunny beaches that I would never know.