Many of us are drawn to science fiction because of the exploration of new frontiers and mind-bending concepts. But let’s all be honest, most of us are a little disappointed if there aren’t a few aliens in there too. Given that, what can a scientific perspective say about aliens? Is there any truth behind some of the radical movies out there?
In this case, the news is good. A lot of astrophysicists think aliens are out there. Beyond that, they’re pretty mysterious (which is also good for science fiction). After all, no one has actually seen an alien. Here I am not counting the numerous reported cover-ups and conspiracies, but hey maybe those will pan out. Until then, here are my thoughts.
Is intelligent life out there?
Short of administering an SAT test to our extraterrestrial visitors, we have no way of knowing. However, we can (and do) speculate all day.
A naive assignment of probabilities says yes. There are ~100 billion (an insanely huge number) of stars in the Milky Way. Given our current planet detection rate, there are many more planets out there. Now, we really should only count hospitable planets, where the temperature is comfortable (read: water is in liquid form) and the surface is rocky (not some swirling gas mix). Even still, we could guess there are something like 100 billion habitable planets too. So we have a large pool to draw from as possible hosts to intelligent life.
We know intelligent life exists by looking in a mirror. Even if the odds are one-in-a-million, we’d have 100,000 other intelligent life forms in our galaxy alone. Note that this doesn’t account for the billions of other galaxies out there. In the greater universe there could easily be millions or billions of alien races.
The missing piece is figuring out those odds. Sure one-in-a-million means aliens are everywhere, but one-in-a-trillion means we’re probably the only ones in the Milky Way. What is that number?
We don’t know, but it’s probably high enough. You may have heard the term “carbon-based lifeforms.” That means carbon is one of the fundamental building blocks of life. It easily bonds with many other elements including hydrogen, nitrogen, and oxygen. These are all over; we can detect them in every star. So those building blocks are out there, and given that, it’s not a stretch to imagine them assembling to form life just like they did on Earth. (Aside – we don’t actually know how this all went down on Earth, so some speculation is built in to that conclusion).
That gets you life, but intelligence. That one I don’t think we have a good handle on yet. We think that life evolved here progressively. But evolution depends on pressure, adaptation, and time. If a planet is too nice, life wouldn’t evolve much because it wouldn’t need to. A little chaos, and even mass extinction, is good for progress. Then again, too much and complex life would get pulverized before it could form. So planet conditions really matter and we don’t yet know what is “normal.”
Still, even if that is a rare occurrence, it’s a good guess that it’s not vanishingly rare. What we know about the galaxy today suggests that the formation of intelligent life elsewhere is quite possible.
Why haven’t we seen any?
Again, I’m acting under the assumption that conspiracy theorists are wrong on this count. But in fact, we may have already seen life. If not through UFOs, then perhaps through unexplained observations in astronomy. Although there is no likely evidence, alien life could be the cause of several strange phenomena.
Otherwise, the most straightforward answer then is the size of the galaxy. Things are far apart and even if aliens had super great spaceships, it takes a long time to travel between planets – decades, millennia, maybe even millions of years. We can barely get to our own moon. That means there probably isn’t any space-faring life nearby (unless it’s hiding).
On a related point, we’re hard to find. Signals from Earth are modest at best and weaken rapidly as they travel from the planet. That limits detection range severely. So again, we’re kind of stuck with either crazy-super-advanced aliens or ones that are quite close by.
There are other, more speculative, reasons out there. Maybe the aliens are avoiding us for some reason (shouldn’t have badmouthed them behind their backs). Perhaps there is some other force (natural or artificial) that regulates intelligent life and has kept it from us. Or it could be that we really are the only ones (which also makes for a good story in its own way, as well as intense philosophical and theological debates).
Whatever the case, the absence of detection has left things wide open for stories.
Aliens in sci-fi: the (pseudo) responsible approach
If we want to restrict ourselves to the most plausible scenario our first contact would be with unicellular life (bacteria or similar). Kind of boring. One could possibly spin this into some scenario in which the bacteria cause mutations in Earth life making some horrific monsters. Or maybe they turn puppies into angels. Who knows. You’ll only get so much mileage from this one.
Then let’s jump to the other extreme. The heavily favored sci-fi aliens are humanoid. That is, they have a head, eyes (maybe three!!!), two hands, two legs, and a torso. Appealing because we can relate to these things more directly, but unlikely in reality. Stop and take a look around anywhere today. Four-legged creatures abound, but so do those with wings, flippers, and six legs. Plus we’ve got whole hosts of weird things with shells, squishy bodies, and tentacles. No shortage of shapes and sizes.
Now this is just on Earth. Imagine if conditions are different on another planet. Lighter gravity would allow bigger creatures. More water and aquatic life could dominate. A hotter sun and everything might need flat bodies to keep cool. The forms intelligent life could take are countless. Humanoid shapes are certainly still possible (and easier to cast in movies), but I’d love to see some more creative shapes working their way into popular sci-fi.
Besides looking like humans, sci-fi aliens usually act like humans. They embody our virtues and our vices. Some seek to save our planet from self-destruction (because they are more enlightened). Others want to conquer us and force humans into subjugation. While these may be thematically relevant to readers, they aren’t necessarily representative of alien behaviors.
True, evolution seems to favor competitive species. Even given that, the particular wants and needs of one alien culture, especially a space-faring one, are unlikely to resemble our own so precisely. Some species may have never faced a scarcity of resources, others could have a symbiotic relationship with sea slugs. Who knows. I think it would be fascinating to explore a species with a completely different values system.
In any case, the options are endless. Already many amazing types of aliens have been imagined, but this is a boundless pool of creativity. Imagine what we might see. I am as guilty as any writer of falling into the trap of modeling aliens after humans. That said, I’d hope to be among those who expand our minds and try to envision what true aliens might look like. Just make sure they're still fun to read about.
Science fiction draws its inspiration from...you guessed it - SCIENCE!