I’ve been memorizing songs during lockdown. First up, Monty Python’s “Galaxy Song” with lyrics by my idol, Eric Idle.
Why start with that one? I’ve always loved space, and wanted to be an astronaut when I was a kid, but I’ve been wearing coke-bottle glasses since age 8, so that idea was a nonstarter. But I kept my love for space alive by being an avid science fiction reader all my life, also hoping to write a great space opera someday.
My favorite space opera is Babylon 5, a fantastic five-year story arc about a space station with numerous aliens coexisting more or less peacefully because the station was neutral territory. I loved the different political stances of the aliens and all the social manipulating and alliances and betrayals. But it’s all just a great yarn, because that will never happen, at least for humans.
The Galaxy Song is all about the distances of space: “our galaxy itself contains a hundred billion stars,” “we’re 30,000 light years from Galactic Central Point,” “[our galaxy] bulges in the middle, 16 thousand light years thick, but out by us it’s just 3,000 light years wide.”
For a long time, people have been trying to figure out why we haven’t seen signs of any other beings in space. There’s a famous equation for trying to calculate if there are intelligent civilizations elsewhere in our galaxy, called the Drake equation. It starts off with the number of stars, divided by the possible number of stars with planets, divided by the possible number of planets with life (which means basically single-celled pond scum), divided by the possible number of planets with intelligent life, divided by the possible number of instances where intelligent life has created civilizations. That’s a simplification of course, and there are lots of variables, but running the calculations you get a low-end answer of 5, and a high-end answer of around 50,000 possible alien civilizations.
The problem with meeting any of them is time and distance. Our closest neighbors are three stars in the Alpha Centauri cluster, 4.3 light years from here. One of them has six exoplanets, and one of those planets, Proxima Centauri B, is of similar size to earth, so, hey, let’s go!
But wait a second, even if we could travel at 1% of the speed of light, it would still take us 400 years, and we can’t even do one-tenth of one percent yet. What’s the fastest speed our spaceships have achieved so far? Scientific American showed me that NASA’s Solar Probe Plus will hit about 200 km/second or 450,000 miles/hr when it goes around the sun, which is 0.067% of the speed of light, and remember that was an unmanned probe. Yeah, at that speed we could go from the earth to the moon in half an hour, but we’d be squashed pancakes when we got there.
Let’s go on the space shuttle instead, which can travel at 5 miles a second, or 37,200 years to go one light year. So that would be 159,960 years to Alpha Centauri. And that’s our nearest neighbor.
Another problem with meeting other civilizations is not just time spent travelling, but also the history of time. We’re out in the sticks, on an outer spiral arm of our galaxy, and our sun is just under 5 billion years old, about the same age as the stars in the Alpha Centauri cluster. A star of our type will live about 10 billion years, so our star is middle aged.
Most of the stars at the center of our galaxy are around 10 billion years old. They’re old stars. If planets orbiting stars like ours are typically best for life while their stars are in middle age, then for the planets orbiting the stars at the center of our galaxy (and that’s the majority of stars in our galaxy), life has already come and gone.
Civilizations are of much shorter duration than planetary life. If you include the Byzantine Empire, the Roman Empire lasted about 1800 years long, and that’s the longest in our human history. We’ve only had civilization for aroundt 6,000 years altogether. So what is that? Ten-thousandth of a percent of the life of our planet?
How do you find civilization on another planet when civilizations are so short? Even if 50,000 civilizations all appeared at the same time, think how hard it would be to find one if you have to check one hundred billion stars to find them (that’s one civilization for every twenty million stars). Just to give you an idea, if you gave 475 people anywhere in the world a flashlight (about one in twenty million), told them to point it at the sky for 90 seconds (about one-thousandth of our day), and then asked some random person in a small two-seater airplane to go look for a flashlight, you’d still have far more than 10 times better chance of finding a flashlight than of finding a planet with a living civilization on it. Just because the pilot can’t find one doesn’t mean they’re not out there, it’s just a vanishingly small chance you’d ever find one.
So, yeah, it’s highly likely that other civilized life forms exist or existed on some other planet in our galaxy. But we’re never going to meet.
Never mind, I’m still going to write my space opera, and there will be LOTS of cool aliens in it.