Okay Fine, Let’s Talk About Aliens

As a Planetarium educator who is also generally known as “the space nerd” to anyone who gets to know me for longer than thirty seconds, I frequently get asked what I think about aliens. The question has come up even more frequently of late, what with the US government having hearings on UFOs, the Mexican government having hearings about alien corpses, and NASA releasing reports on UAPs (unidentified aerial phenomena, because unidentified flying object is so 20^th century). Aliens are kind of having a moment.

Based on all I’ve learned in my life about physics, astronomy, spacecraft, and most especially humans, I have come to the following conclusion: I absolutely believe there is life out there in the universe. I also absolutely believe none of it has ever come anywhere near Earth. You are, of course, free to draw your own conclusions from available evidence, but if you’re at all curious, here is how I arrived at mine.

Life in the Universe

We currently know of exactly one place in the entire universe where we can say for certain life managed to develop: Earth.  So we have a sample size of one when we’re looking at planets which give birth to life. Here’s a few things we don’t know, as a result: what are the conditions required to give rise to life? Is there more than one set of conditions where life could arise? If the right conditions exist, is life all but guaranteed to arise, or is it a crapshoot and life will only occasionally appear, even if everything is in place for it? Without knowing the answers to these questions, we really can’t guess how frequently life will turn up throughout the universe. 

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But here’s the thing, the universe is so big and filled with so many worlds that it kind of doesn’t matter. The scale of the universe is something that is tricky for puny human brains to comprehend. Even if the genesis of life turns out to be one of the rarest occurrences in the universe the odds of it only happening once on our little backwater world are so small as to be ignorable. There’s life out there, somewhere. The question is really how much of it there is.

But not all life is the same, at least not when you want to get around to talking about UFOs and UAPs and alien corpses in the government basement. Even if we someday find that there are fish in the underground oceans of Enceladus or plankton floating in the seas of K2-18b, discoveries that would be absolutely incredible to make, none of those critters is likely to be piloting a flying saucer anytime soon.

The Drake Equation

Dr. Frank Drake was an eminent astronomer with a storied career that spanned decades, but today he’s largely known for the thought experiment he engaged in at the first scientific meeting on the search for extraterrestrial intelligence (SETI) in 1961. He came up with a formula that still bears his name to think about the frequency of intelligent life appearing in the universe. Among other things, it takes into consideration the rate of star and solar system formation, the fraction of planets that could support life, the number of those planets on which life actually appears, and the percentage of life-bearing worlds that will develop intelligent life. 

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Simple lifeforms like bacteria are much more diverse and hardier than more complex lifeforms. It seems likely, then, that a lot of the life that is potentially flourishing out in the universe is something quite basic. With our sample size of one, we have absolutely no idea how frequently those simple critters will evolve into a technologically advanced civilization capable of sending radio signals out into space, let alone spacecraft.

Theoretically though, the Drake Equation suggests that there could be many advanced civilizations amongst the stars. This has given rise to another thought experiment: the Fermi Paradox, named for physicist Enrico Fermi who, while discussing UFOs one day during lunch, supposedly blurted out “Then where is everybody?” After all, we’ve been actively hunting the skies for any signs that could even hint at an advanced alien civilization for many decades and have found nothing convincing. Where are all of these supposedly advanced aliens hiding? 

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Many thoughtful folks have come up with many thoughtful solutions to the Fermi Paradox. It’s genuinely a fun thing to think about, or at least I think so. But several of them revolve around a term in the Drake Equation that I haven’t mentioned yet because it tends to give folks the collywobbles.

The final term in the Drake Equation is L, the length of time the average advanced civilization will survive. It’s a number we can’t ever know because the day we know it for our own civilization will be the day it ends. Many of the solutions to the Fermi Paradox revolve around the idea that L is not nearly as large a number as we’d like to hope it is, and certainly not large enough for a civilization to make much of a mark on the universe.

Alright Fine, Let’s Talk About UFOs

But let’s assume, for a moment, that there is such an advanced civilization here in the Milky Way. For the sake of argument, we’ll even say they’re relatively close by, a hundred light years away (our celestial backyard), and have managed to hide themselves, their biosignatures, and their technosignatures from us somehow. And they have, for reasons, an unquenchable desire to visit Earth. How would they get here?

The nearest solar system to our own is around our stellar neighbor Proxima Centauri. It’s about 4.25 light years away. If we sent a spacecraft, using our current technology, to that solar system, it would take roughly 70,000 years to reach it. And that’s our next-door neighbor. Reaching something a hundred light years away, a very short distance the way things go in space, would take nearly 2 million years of travel. I can’t imagine anyone wanting to visit Earth that much. 

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But since we’re doing things for the sake of argument, let’s say this alien civilization has incredibly advanced methods of travel that will allow them to move close to the speed of light, and that they’re even closer than a hundred light years. Would you commit yourself to a one-way trip of several decades just to see Earth? Why? And if you’ve got such advanced methods of travel, why would you be as bad at flying through Earth’s atmosphere as supposed alien sightings suggest? Seriously, they seem to crash a lot (and then wind up in Pentagon labs or in boxes in Mexico apparently).

But okay, for argument’s sake again, let’s say you have come here, somehow, from your home planet where your entire civilization has managed to hide all evidence of themselves from the prying eyes on Earth actively searching for you. You’re on your way into the solar system, heading towards the alien Mecca that is the third planet. How come nobody notices you?

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We have telescopes constantly scanning the skies, hoping to see early evidence for transient events like supernovae or gamma ray bursts, or to spy incoming comets or asteroids, or, yes, to try and detect signals from other worlds. Closer to Earth, satellites can’t shift their orbit without satellite-watchers around the globe instantly noting it all over the internet—satellite tracking being a surprising yet endearingly popular hobby. So why has no professional astronomical observatory ever called in the sighting of an alien craft? Why aren’t satellite trackers picking up these incoming ships? That’s their jam!

It seems that sightings of UAPs/UFOs frequently happen in the atmosphere (where, again, these supposed aliens are apparently bad at flying). I have a hard time believing that any race that could traverse the incredibly vast distances of space and make an approach to Earth completely undetected despite the buildings full of technology and reams of people on who devote both their professional careers and their spare time to looking for that very sort of thing would manage to get caught loitering around the sky by a grainy cell phone camera (and it seems like it’s always a grainy camera even in this era of high-def imaging devices being everywhere). 

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Given all of that, does it seem more likely that the bright light in the night sky or the dark spot moving in the atmosphere is a spaceship from another world or that it has some far more mundane (and admittedly far less exciting) explanation? Many UFO/UAP reports can be traced to aircraft, meteors, searchlights, balloons, satellites, the International Space Station, and the planet Venus, which looks too stupidly bright to be natural, but it is. The odds are far better that the ones we don’t have an easy account for are also something with an Earthly explanation than that it’s extraterrestrial visitors.

I’ve certainly never seen a claim of alien sightings or contact that had the proper evidence to back it up. I’ve quoted the God of Science Communication, Carl Sagan, before and I’ll undoubtedly quote him again: “extraordinary claims require extraordinary evidence”. A grainy cell phone vid will never be anyone’s idea of extraordinary evidence.

The Dust Speck

Of course, I’d love to be proven wrong someday. I’d love to find out there are other civilizations out there as much as anyone. I’d love to get a radio signal from another species (hopefully saying “hello” and not “it’ll totally be war when our ships reach you in two million years!”). I’d love for our dust speck of a planet or our little firefly of a star to be thought of as interesting enough to someone to be worth the ridiculous trip. I’d even love for a great big spaceship to plop itself down in the open and for someone to come out and say “hello there” (why yes, that was an oblique Star Wars reference, thank you for asking).

I’m just not gonna be holding my breath about it.