Why Haven't We Discovered Aliens Yet? | Unveiled

VOICE OVER: Noah Baum WRITTEN BY: Dylan Musselman
We've been searching for alien life for decades... but still nothing! In this video, Unveiled unpicks the Drake Equation to find out why we're still alone in the universe. Physicist Enrico Fermi famously asked; "Where are they?"... but we've yet to see proof of even microbial life. Why do you think we haven't discovered aliens yet?

Why Haven't We Discovered Aliens Yet?

When contemplating the likelihood of life elsewhere in the Universe, we often look at Earth as a starting point. Our planet is about 4.5 billion years old, with the first signs of life as we know it appearing as long as 3.7 billion years ago. It’s suffered many different mass extinctions since then and yet, here we are, still living and breathing. In some ways, this shows that life can evolve rapidly given the right circumstances and that it’s extremely hard to 100% eliminate. But if that’s true, then shouldn’t we have also seen signs of life elsewhere by now?

This is Unveiled and today we’re answering the extraordinary question; Why haven’t we discovered aliens yet?

When pop culture pushes aliens, we get the tried and tested image of big-headed green beings with black eyes and flying spaceships. But when actual researchers look for aliens, their expectations are much simpler. Exobiology is the science of studying and researching possible alien life in the universe. And “alien life” refers to any kind of life that doesn’t originate on Earth, including even simple organisms like bacteria or single-celled prokaryotes. Intelligent alien life is the dream for many, but it’s believed that it would be even rarer (that’s even rarer than those basic alien microbes, the like of which we’ve never encountered!). Intelligent life requires that simple lifeforms survive and reproduce through planetary disasters and despite potential predators, including themselves - much in the way that we have done. Some argue that intelligent life is inevitable in time and that evolution favours intelligence… so, if aliens do exist, then at least some of them should be smart! On the other hand, others say that self-destruction among intelligent species could also be inevitable - meaning aliens might well kill themselves off before we ever cross their paths.

So, all of that considered, what are the actual chances that alien life exists, and how many aliens could, or should, there be? On the surface it’s an impossible question, but we do have an equation to help us make a prediction. Frank Drake created the Drake Equation which, accounting for a number of variables, provides a potential way to work out the prevalence of life in the Milky Way, and the universe. In the equation, “N” is the number of potential alien lifeforms that we could communicate with. We arrive at “N” by first taking the rate of star formation per year and multiplying it by the number of those stars that are likely to have planets. Multiply that by the number of those planets that exist in a habitable zone; then by the fraction of those planets that actually develop life; then by the fraction of those lifeforms that develop intelligence; then by the number of those intelligent species that develop communication technologies; and finally, by the average lifetime in which our intelligent, communicative, alien species is able to put that technology to use.

It’s not what you’d call “simple math”(!), but it does at least provide us with a means to predict the commonness of alien life. The problem is that answers to the Drake Equation tend to vary wildly! Many of the variables within it are also unknowable, meaning every application of the equation is made using other wide-reaching estimates; like the ten billion trillion stars predicted in the universe, and the 1 in 5 stars thought to hold at least one planet in their habitable zones. For example, say you assume the odds of intelligent life developing on a given planet to be one in 500 million, then - depending upon how you view the equation - that could mean that there have been roughly twenty billion civilizations like our own in the history of the universe. But nothing can be said for sure, and no amount of number-crunching answers our immediate alien query; where are they all?

Well, if our physics is right, then no amount of matter can go faster than the speed of light, which drastically limits the distance we can search. Imagine how little contact groups would have on Earth if our lands were separated by millions and millions of miles of ocean. When looked at through our own technologies, space is just massive. Say there is an intelligent civilization just 5,000 light years away from us… it would take 10,000 years for us just to receive a single reply from them. For context, go back 10,000 years in the whole of human history, and we were only just inventing the concept of farming.

The sheer size of the cosmos means that we’re effectively left looking for alien life in the distant past. We use spectroscopy, a technique for viewing and analysing the atmospheres of distant planets, to look for potential signs that something lives, could live or might have lived so far away from Earth. But were we to look for something such as methane, a possible predictor of life given that most methane on Earth comes from biological organisms, on a planet that’s 1,000 light years away, we’d actually be seeing it 1,000 years in the past. Because that’s how long it takes the light to reach us… which means that if, say, life developed on that planet 200 years ago, we wouldn’t know anything about it for at least another 800 years. We’re working in totally different time periods, and it’s one of the biggest stumbling blocks in our search for aliens. And then, even if we did come across the right combination of gasses and elements, when viewing from a distance, without super, super, super advanced telescopes we’d still need to actually visit the planet (or at least that planet’s star system) to see and confirm extra-terrestrial life beyond doubt. And that just isn’t happening with our current technology.

So, the chances of us, ourselves, discovering and verifying alien life are for now fairly low… but what of those potentially intelligent extra-terrestrial species? If they - as per the almost infinite variations of Drake’s Equation - have better technology, then why haven’t they visited us?

Well, even with peak technology, they could still be flummoxed by the same limitations that hinder us… faster than light travel may be just as impossible in every other corner of the universe as it appears to us in this one. And then the question boils down to the unscalable distances once again, with beings even in just our galaxy - the Milky Way which in itself is more than 100,000 light years across - perhaps never getting the chance to know of us. Of course, there are also theories that aliens have visited Earth in the past, or another solar system planet, or another spot in our galaxy, and simply missed us. Or theirs and our timelines unfortunately failed to crossover. If you subscribe to the idea that most civilizations inevitably self-destruct, then there’s only ever a certain window in time that any two civilizations could even feasibly exist at the same time as each other.

And finally, there’s the idea that aliens are aware of us, but they decide not to visit or to make their presence known. In this way, we haven’t discovered them yet because they don’t want us to. And there could be a number of reasons why this would be the case. For one, advanced enough extra-terrestrials could consider visiting us - a world otherwise oblivious to the outside universe - to be morally questionable. For another, incoming aliens could worry that we’d be hostile, given the wars, fighting, death and destruction that humanity has created amongst itself.

Failing that, and as per another popular theory, we could be little more than subjects of a controlled experiment for higher, alien powers - a means to test the possibility of organic life evolving and becoming intelligent. Or a trial group to determine whether the set-up of our solar system is safe or efficient. Or, even more simply, we could be a form of entertainment for some far-off alien overlords, who never intend on making themselves known because why should they?

The suggestion that, if there is alien life “out there” then it’d be they who’d be in control is key here. We haven’t discovered them because 1) they haven’t allowed us to, and 2) because they’re really good at hiding. In fact, were their general composition to be sufficiently different from our own carbon-based bodies, we wouldn’t necessarily even be able to detect or understand them as living things. It’s not as though physically implausible, totally unobservable beings infiltrating our own life experience is really something we should be overly paranoid about… but it would go some way to answering why we’ve yet to unveil proof of aliens.

However you implement it, Drake’s Equation suggests that based on the sheer size of the universe alone, and the phenomenal number of planets it houses, it is very likely - perhaps far more likely than not - that alien life exists somewhere. But inferring life from such incredible distances is very difficult. Turn the problem on its head and, from a comparable distance “in the other direction”, maybe Earth wouldn’t appear an obvious, bankable host for life either!

We most likely haven’t seen aliens, or they haven’t seen us, because we’re simply too far away to know for sure, and definitely too far away to communicate. The other, much more ominous scenario puts humanity at the mercy of ultra-advanced alien superiors who might never reveal themselves to us. Whichever explanation you think rings true, it’s a problem that’s sure to continue fuelling scientific, philosophical and existential debate. And that’s why we haven’t discovered aliens yet.