What Would an Alien City Look Like? | Unveiled

What Would an Alien City Look Like?

For so long, humankind has tried to understand what an alien civilization would look like. Science fiction movies are crammed with rich imaginings of extraterrestrial technology, cities on distant planets, and whole, sprawling societies in space. But, in reality, what are we really expecting to find?

This is Unveiled, and today we’re answering the extraordinary question; what would an alien city look like?

Today’s topic can really be split into two parts; what could an alien city look like up close? and, what would it look like from Earth? In the first part of this video, we’ll take a look at the first question. And, in the second part, the second question.

Up close, theories abound as to what an alien world would be like, how it would be built and how it would function. And mega machinery is usually the first port of call for anyone picturing life on different planets. In general, humans tend to automatically elevate aliens in our mind’s eye, to something more advanced than us. We figure that microbial life might well exist in subsurface oceans somewhere… or high in an atmosphere… but smart alien life moves to land (like we did) and begins to build and build until it achieves mastery of its planet. According to some models, that also involves it returning to the oceans and skies, to live on (and in) them safely. But what needs to happen to bring an alien race to this imagined point? And what machines are we keeping our eyes open for?

Cosmic megastructures range from the relatively small fry of space elevators and large, artificial satellites… to star-system-conquering stellar engines like Dyson spheres, Dyson shells and Shkadov Thrusters. We’ve published videos about these machines in the past, so we won’t go into detail here… but suffice to say, any civilization with any of these at its disposal is considerably more advanced than we are! When they look to the sky, they don’t see an expanse that’s impossibly far off… they see a cosmos waiting to be tamed.

The perfect alien city is one that uses energy as efficiently as possible. It’s probably siphoning that energy from nearby stars and otherwise inhospitable planets, to ensure that it always has a reliable supply of power. In much the same way as our cities chiefly provide shelter, an alien city would need to do the same - but there’s no real reason to expect buildings and skyscrapers in line with how our civilization has grown. Smart aliens could just as well live predominantly underground, underwater, or inside vast biospheres. Perhaps they’ve mastered floating cities, the like of which have been suggested as a potential way for humans to colonize Venus.

Clearly, without any real-world examples to go on, it’s impossible to know with any certainty the form an alien metropolis would take. But another reason that it could appear unusual to our eyes is gravity. We of course know that the effects of gravity aren’t the same everywhere. From here to the moon to any other celestial body, they fluctuate depending upon the mass that’s around. And, although we rarely think of it this way, our cities work in harmony with the force of gravity on Earth. Buildings rarely fail just because gravity can’t accept them. On an alien planet, though, different gravity could mean different rules… different shapes of buildings… and if the aliens inside the buildings weren’t naturally evolved to their own gravitational conditions, then perhaps a means of artificial gravity would be needed in every enclosed space.

In general, in this highly speculative, other-worldly reality, we do need to think about the city’s population, too. On Earth, our cities are fundamentally designed with humans in mind. Doorways, sidewalks, storeys in high-rises, bridges and roads… they’re all made to accommodate for our particular size and shape. Hospitals, museums, airports, libraries and sports fields… they’re all reflections of what a human civilization does and needs. But all of that could be totally irrelevant to how an alien species operates.

Again, science fiction so often imagines aliens to be varying degrees of humanoid. Creatures with limbs and heads and human-like senses. But science fact doesn’t usually reach the same conclusions. And we don’t assume that even the most fundamental aspects of human behaviour would be shared between us and them. They might not need (or want) to physically move around as much as we do - so a city built around transport links wouldn’t be necessary. They might not be social as we think of it, so there’d be no need for a city to feature meet-up points like parks and stadiums. There might not be an economy, which would mean no places to work and no places to spend. And as for the question of what smart alien life eats, and where they eat it… obviously nobody knows. But there’s no reason to picture restaurants and bars ala Earth.

So, we have possible mega-machinery, influenced by potentially drastically different natural forces like gravity, and powering a society the like of which we can imagine… but never predict with certainty. That’s all great, but how does even a small slice of that translate into something we can see from here on Earth? Now’s when the real-world science and technology comes in. It’s probably not quite as fun… but it is just as fascinating.

In reality, scientists and astronomers are scanning the skies for radio waves, electromagnetic pulses, and any sign - no matter how small - that a far-off star may have changed, that a planet may have passed in front of it, or that it might be the site of a cosmic megastructure. All of these translate into only tiny observations made from Earth, miniscule blips in an endless stream of astronomical record-taking… but at our current technological level, this data is everything. It allows us to read the sky in more and more detail.

The Wow! Signal, recorded in 1977, still stands as probably the most famous unexplained radio signal of all time, coming from the direction of the Sagittarius constellation. More recently, though, astronomers picked up a similarly strange electromagnetic signal, beaming out from Proxima Centauri - the closest star to the sun. You can check out our recent, dedicated video for more!

Breakthrough Listen is leading the charge in the search for extraterrestrial intelligence in the twenty-first century. It’s comfortably the largest and furthest reaching SETI initiative humankind has ever seen, mapping the stars for radio and laser anomalies, as well as teaming up with multiple major space agencies on an ever-increasing number of SETI projects. Its bases are the Green Bank Observatory in the US and the Parkes Observatory in Australia (for radio) plus the Lick Observatory in the US (for laser). It has both hemispheres covered, then, and reportedly analyses ten times more sky than any previous SETI search.

In the future, we’re hoping to do even more, however. The proposed LUVOIR Telescope is one of four missions vying for the go-ahead from NASA. It will reportedly be powerful enough to detect all artificial light potentially coming from another planet. This means that it could produce similar images to those we have of Earth but of other worlds, taken from space when they’re lit up at night. And, of course, if we ever were to spot a cluster of light twinkling out from the surface of an exoplanet, then it would be the surest sign of alien life we’ve had yet!

Meanwhile, we’re constantly trying to improve the probes we launch from the ground, sending them further afield equipped with more advanced technology than ever before. The Voyagers remain our most distant explorers, and they’ve only just breached the heliosphere, but the New Horizons probe is catching them up. The Perseverance Rover is the latest to land on Mars, and one of its chief objectives is to search for alien life. It’s hunting for biosignatures first and foremost… but in the future, we could see probes sent out with technosignatures most in their sights. Something akin to Perseverance but sent much further away, and at a much higher speed.

Today, we’re increasingly familiar with the images beamed back from Mars, as a rover scours the open plains of the Red Planet. But one day, we might bear witness to similar images, only sent from a human-built robot navigating the streets of a purpose-built alien settlement. The Rare Earth Hypothesis argues that if there is life out there, then it’s exceptionally rare. But even if that turns out to be true, then we’re increasing our chances of finding it year on year.

On some level, we can all contemplate what an alien city would actually look like. We can let our imaginations roam across the mysterious layouts and structures to reveal how another species might live. But science is beginning to fill in the blanks so that soon we’ll have a more solid foundation to world-build off of.

The search for extraterrestrial intelligence is on. It’s gathering pace. And alien life is coming more and more into view.