– In most science fiction movies extraterrestrials are presented as the bad guys and they are part of a hostile invasion force. For some reason, these highly advanced alien beings travel several light years with the goal to destroy Earth and humans.
Many of the extraterrestrial invasion scenarios make a good movie plot, but how realistic are they from a scientific point of view?
An astrobiologist has examined five possible extraterrestrial invasion scenarios and his conclusions are more optimistic and show us we shouldn’t be afraid of our alien visitors.
Lewis Dartnell is an astrobiologist and author from London who has spent many hours working in the lab with samples from some of the most extreme places on Earth, investigating how life might survive on other worlds in our solar system and what signs of their existence we could detect.
Dartnell thinks that most life in the Universe is the vast majority of life in the Galaxy will be microbial, but there is of course a possibility that advanced extraterrestrial civilizations are present on alien worlds we have not yet discovered.
He has offered solid arguments for why we should stop worrying about contact with aliens and why they are not as hostile as many people think.
Perhaps we tend to think that extraterrestrials will try to enslave us because that’s exactly what we have done to other civilization over the course of history.
But we mustn’t forget we are referring to an alien civilization that is much more advanced than us and these beings have capability of voyaging between the stars.
This means they master technology on the most advanced level and can produce highly advanced robots that, or other forms of automation or mechanization that would be a far more effective solution for labor than people.
The idea that aliens would like to breed with us is also rather far-fetched. According to Dartnell “the act of sexual reproduction, on a genetic level, involves the combination of DNA from two individuals. So on the most fundamental level, for an alien race to be compatible with us, they would need not only to use the same polymer, deoxyribonucleic acid, as the storage molecule for their genetic information, but also to use the same four “letters” for their genetic alphabet (and not other purine and pyrimidine bases that exist in chemistry), and the same coding system for translating those sequences of genetic letters into proteins, and the same organizational structure of the DNA strands into chromosomes, and so on.”
We, humans can’t even breed with interbreed with our closest evolutionary relatives on Earth, the chimpanzees. So, the thought that aliens could breed with us seems very unrealistic.
If aliens would like to eat us, then these extraterrestrial beings will need to be based on very similar biochemistry, and thus have the enzymes needed for processing the molecules we are built from. Dartnell thinks that there is a possibility aliens are made of the same stuff as us. After all, amino acids, sugars and fatty molecules have all been found in meteorites, suggesting they’re common across the universe.
However, harvesting us for food is more complicated than it seems. Enantiomers, simple organic molecules can occur in mirror images of each other. As Dartnell says, it’s like how your two hands are the same, but can’t be placed atop each other in alignment. All life on our planet has “left-handed” amino acids and “right-handed” sugars, and any creatures looking to us for sustenance would need to have the same, even if they do share our basic microbiology.
“Alien invaders could be based on exactly the same organic molecules (amino acids, sugars, etc.), but they still wouldn’t gain any nutrition from eating us as the origins of life on their own planet settled on the opposite enantiomers. We’d be mirror images of each other, on a molecular level,” Dartnell says.
Water is a necessity for life as we know it, but our planet isn’t that unique. There are many far better sources of water in space than planet Earth. You don’t have to look far to see there is plenty of water elsewhere. Europa, one of the moons orbiting Jupiter, contains more liquid water in the global ocean beneath its frozen surface than our entire planet.
Some have suggested that extraterrestrials may want to invade the Earth to exploit. Perhaps they are interested in some other natural resources than water, but that’s unlikely too. “Because the Earth formed from a molten state with iron sinking down to the core, our planet’s crust is actually pretty depleted of useful metals like iron, nickel, platinum, tungsten and gold. And as with the water, it’s hard to see why aliens would bother extracting material against the gravity of the Earth when the asteroids are composed of the same basic rocky stuff,” Dartnell says.
It’s not impossible that an extraterrestrial civilization would like to colonize our planet, but we must once again consider our alien visitors advanced technological knowledge. According to Dartnell these extraterrestrial beings are most likely already familiar with the concepts of “mega-engineering” or “geoengineering” and they avoid the worst effects of global warming on Earth.
The fact that “Earth is already teeming with its own life (most of which is tenacious microbes that affect the chemistry of the atmosphere and oceans) may well be a hindrance to an alien species, with its own quirky biochemistry, looking for somewhere to colonize. It may well be easier to find a terrestrial world that hasn’t already developed life of its own, and install its own biosphere on an empty planet.”
So, finding a planet without life elsewhere would be much easier for the aliens.
Dartnell thinks that extraterrestrial may have a very different agenda than proposed in many sci-fi movies. If they come to Earth and make open contact, it may simply be because they want to meet us. “I suspect that if aliens did come to Earth, it would be as researchers: biologists, anthropologists, linguists, keen to understand the peculiar workings of life on Earth, to meet humanity and learn of our art, music, culture, languages, philosophies and religions, ” Dartnell says.
Perhaps we simply think too much in human terms when we imagine our first contact with advanced alien life-forms.