The evidence which proves aliens are real could be lurking undiscovered beneath our feet.
That’s the suggestion in a new piece of research which considers the possibility that extraterrestrial civilisations may have settled on Earth.
The study does not explore the ‘intent and motivation’ of alien civilisations, which means its authors do not discuss whether extraterrestrials are likely to be monstrous hunter-killers hellbent on galactic destruction or peace-loving ‘take me your dealer’ hippies dedicated to spreading love throughout the cosmos.
It instead calculates whether extraterrestrial ‘exo-civilisations’ could travel throughout a galaxy and goes onto consider whether they may have ever reached Earth.
However, if they did manage to find Earth and live here it could be very difficult to find traces of their settlements because all evidence would be obliterated over time.
The paper is inspired by the ‘Fermi Paradox’ which describes the contradiction between the high likelihood of aliens existing somewhere out there in the universe and the ‘Great Silence’ caused by the fact we’ve seen absolutely no sign of civilisations living anywhere but Earth.
‘If civilizations have a finite duration, then it is possible that Earth was settled some time in the distant past and all traces of that settlement have been erased by geological evolution,’ the team wrote in an early version of their paper, which has now been peer reviewed and published in The Astronomical Journal.
They added: ‘How long ago could Earth have been (temporarily) visited or settled by such a civilization without leaving any obvious trace?
‘If the settlement occurred 4 billion years ago and lasted for just 10,000 years would any record of it survive in the geological record?
‘The answer is: almost certainly not. This implies a temporal horizon over which a settlement might not be “seen”.’
There’s also a chance that aliens got to our solar system and decided against staying here, the paper continued.
The authors counselled against trying to understand extraterrestrials in human terms and added: ‘The assumption that the Earth’s life-sustaining resources make it a particularly good target for extraterrestrial settlement projects could be a naive projection onto exo-civilizations of a particular set of human attitudes that conflate expansion and exploration with conquest of (or at least indifference towards) native populations.
‘One might just as plausibly posit that any extremely long-lived civilization would appreciate the importance of leaving native life and its near-space environment undisturbed.’
Professor Stephen Hawking famously feared that an encounter between humanity and an alien species would be disastrous.
So you may be slightly alarmed to hear that one scientist recently suggested that extraterrestrial invaders ‘may already be on their way’.
Jacco van Loon, an astrophysicist at Keele University, issued a rather scary warning about light pollution here on Earth.
He said that we may have already given away our location to a non-human civilisation because we light up the planet every single night with electric illuminations.
For a sense of what our first encounter with aliens might be like, we’d urge you to remember that Hawking also said extraterrestrials could be ‘rapacious marauders roaming the cosmos in search of resources to plunder, and planets to conquer and colonize’.
‘Meeting an advanced civilization could be like Native Americans encountering Columbus,’ he continued. ‘That didn’t turn out so well.’
In an article for The Conversation, Mr van Loon, astrophysicist and director of Keele Observatory at Keele University, wrote: ‘Images of the Earth at night reveal our presence in spectacular fashion. Cities and roads outline the contours of continents, while oil platforms dot the seas and ships draw lines across the ocean. This type of light, which has replaced older, incandescent sources, is unnatural. From the orange sodium or bluish mercury lamps to white-light-emitting diodes (LEDs), the artificial origin of this “spectrum” should be easy for technologically advanced aliens to spot.
‘In the coming decades, Earth’s space agencies may be developing the means to detect such artificial light from planets around other stars. But we may fail, if aliens believe the smartest thing to do is to keep quiet and remain in the dark. We, on the other hand, may already have been seen, and they may already be on their way. This begs the question – should we dim our lights, before it’s too late?’
He went on to warn about the potentially disastrous effects of light pollution and the well-meaning, but potentially ruinous, decision to send radio transmissions out into space in the hope aliens will pick them up.
‘Since the first use of electric lamps in the 19th century, society hasn’t looked back,’ he continued.
Homes and streets are lit at all hours so that people can go about their business when they’d once have been asleep. Besides the obvious benefits to societies and the economy, there’s growing awareness of the negative impact of artificial light.
‘Light pollution has been blamed for wasting energy, disrupting wildlife behaviour and harming mental health. One aspect has avoided the spotlight though. Namely, that light not only allows one to see, but also to be seen. This could well attract unwelcome attention – and not just from moths.
‘The innate curiosity of humans and our growing knowledge of the universe in which we live have led us inexorably to a question. Do civilisations exist on planets other than Earth? Scientists now believe that there are many places in the universe which might harbour simple lifeforms such as bacteria.
‘What is more speculative is the notion that such extraterrestrial life could have become technologically advanced, perhaps even well beyond our capacity. This idea has captured the imagination of the general public, giving birth to a rich collection of science fiction literature and blockbuster films. But it has also received serious attention from scientists, who have thought of ways to find and possibly contact these alien species.
‘In 1974, radio astronomer Frank Drake used the then most powerful radio transmitter, at Arecibo in Puerto Rico, to broadcast a message into space announcing our presence. The message will now be 45 light years away from us. While there are many stars and planets closer to us than that, they won’t have been in the path of Drake’s broadcast.
‘But impatient as scientists tend to be, more effort has gone into searching space for such signals transmitted by extraterrestrial civilisations. As more and more planets are discovered around other stars, the search for extraterrestrial intelligence – often abbreviated to SETI – is becoming more relevant, better informed and better resourced. In 2015, wealthy entrepreneurs Yuri and Julia Milner allocated US$100m to the Breakthrough Listen SETI project, which buys time at observatories to use their powerful telescopes to detect artificial signals from outer space.
‘Despite the vastness and emptiness of space, scientists have started to wonder why we haven’t heard from aliens yet. This puzzle is known as the Fermi Paradox, named after the physicist Enrico Fermi. Among the many solutions proposed for this problem, one really brings us down to Earth: aliens might be scared of other aliens.
‘While tempting, many scientists now agree that sending messages into space without knowing who might be intercepting them might not be such a good idea. Once sent, it cannot be undone. Unlike a post on social media, it cannot be removed. Listening is much safer. But radio communication among ourselves – which includes navigation, television broadcasts and the internet – might also be detected from space.
‘After all, radio waves that aren’t captured continue to travel, up and away from the Earth into deep space. Unintentionally, we may already have been observed by an amused, terrified or “interested” species, who may decide to meet us to “shake hands”, or come to enslave us, eat us, or destroy us as a precaution. We are, after all, an aggressive species ourselves.
‘Fortunately, Earth has become a lot quieter, thanks to more directed signalling and fibre cables replacing aerial transmission. We might just get away with our past recklessness. But a new beacon is brightening.’