For over 40 years now, fans have been entranced by the simple story framing the beginning of every Star Wars movie. Naturally, there’s no reason for any of us to doubt that Star Wars did actually happen—the size and scope of the universe suggest that anything’s possible, so we might as well believe that the Death Star really did exist once upon a time. But when exactly is “A Long Time Ago”?
Patrick Johnson of Georgetown University believes he has the answer. In his new book, The Physics of Star Wars: The Science Behind a Galaxy Far, Far Away, Johnson endeavors to answer a variety of questions about how Star Wars might have played out—including when this all went down. While Star Wars may have taken place “A long time ago” in terms of the age of human civilization, the historical events they chronicle took place relatively recently in terms of the age of the universe. The movies show off hundreds of species of aliens, strewn across countless inhabited planets. These didn’t form overnight—it would have taken around 5 billion years for the Star Wars galaxy to form, and for all of its stars and planets to take shape. In fact, some planets seen in the movies may still be fairly young—the volcanic planet of Mustafar, as seen in Revenge of the Sith and Rogue One, might not always be such a big, bubbling mass of lava and ash. Many planets, including our own (and even the big moon that orbits our homeworld), undergo an awkward lava phase when they’re relatively young, as they burn up a lot of their pent-up energy as heat bursts out of the planet’s core.
This is actually a key step in a planet-forming an atmosphere, as a gas that’s released from the volcanic eruptions swirl around the planet afterwards—although the air generally isn’t as breathable as it appears in Episode III. Similarly, the ice planet of Hoth could simply orbit its sun at a great distance, but it also has an oxygen-rich atmosphere and native tauntauns and wampas, which suggest that the remote hunk of rock might simply be an Earth-like planet that is going through an ice age. Our own homeworld has had several periods of cold freeze over its history, so it’s not too far of a stretch to assume that, a few million years later, the ruins of AT-AT walkers might be covered in grass and flowers.
All in all, for Star Wars to have occurred, the Big Bang would have needed to start off the universe, the galaxy would have needed to form, and all the star systems and planets—both old and new—would have needed time to mature. Then, it would have been another long wait for life to develop to the point of sentience before Jedi, Sith, smugglers, and pirates could all start whizzing around the stars at light speed.