Much has been written about the structure of the universe, of nature, of matter itself. And a lot focuses too on the nature of life and whether it exists outside the earth we know and love. Through all these discussions and debates, it's pretty remarkable how our theories are tinged with a self-righteous sense of arrogance.
Early religious cosmologies held that the earth was the center of the universe, because what arrangement could be more perfect? It was religious heresy to argue otherwise. Copernicus, who suggested that a heliocentric solar system made sense with our observations as opposed to a geocentric system, published his ideas in secret. Galileo, who used a telescope to observe that moons orbit other planets (and not the earth), was forced to publicly recant his theories. Kepler was luckier and supported heliocentrism openly, though he was careful not to step on too many religious toes. Through all this, note the intense resistance to the idea that we are not at the center of the solar system and the universe.
We dropped this idea and replaced it with the general theory of relativity. And the next hot topic is who else exists in the world with us. It's a topic that has gained a lot of treatment in movies, TV shows, comics, cartoons, novels and short stories. And incredibly, we see the same arrogance in all these media, wherever the idea is expressed.
One prime example of this arrogance is how all these creatures are depicted as being humanoid, with human attributes. Why would we ever assume that alien creatures will be humanoid? Probably because we think that life elsewhere in the universe would develop the way it did on earth. Is this reasonable? Maybe. There is an inherent bias towards the idea, because it's the only way of developing life that we know of. But how probable is this?
How did
life develop on earth? It started with the primeval soup, from which
arose self-replicating organisms, which diversified and consolidated to form the several
kingdoms of life we see today. Conditions had to be just right for life to rise and survive - distance from the sun, composition of the atmosphere, the presence of water, the speed of light, laws of physics, so on and so forth. With
the billions of stars and star systems that exist in the known
universe, it's quite feasible that one of them will have conditions
exactly like our primeval soup, with all the right conditions to produce
life. But why assume this is the only initial state that will lead to
life? If there is a different initial state that can lead to life, that life form could be very different from what we (carbon-based and self-replicating) are.
Even if a primeval soup
existed elsewhere which gave rise to self-duplicating creatures like we
are, why assume that the "humans" on that planet are the ones who will
ultimately survive? Through the ages, an incredibly wide variety of species have developed within each kingdom. Our species wasn't even the top dog
until between 2 and 3 million years ago (compared with 4.6 billion years of
earth's existence). Reptiles dominated for a long time, chiefly the
large-boned, muscular variety whose brains couldn't develop much beyond
"eat food, catch meat". They were mostly killed off 65 million years ago, which paved the way for mammals to diversify and become dominant.
If aliens are humanoid, are we trying to say that whatever planet they come from also went through all these developments? That they too had dinosaurs who died out and allowed humans to flourish? For all you know, it could be the fish or the mushrooms who are the
dominant species.
The next
idea is of course, such humanoids exist, and they have developed
technology far more sophisticated that what we've produced. And that these alien humanoids will want to kill us and take over our planet.
Of all the thousands of species that have lived and
died out through the history of earth, only one has developed enough
self-awareness to study the laws of physics. How likely is
this to have happened on some other planet? Remember, they have to first survive ice ages, dinosaurs and asteroids.
The fear of conquest by aliens arises, I think, from our observations of our own species. Human civilizations have battled each
other, conquered one another, with devastating consequences for the
losers of the war. Hence we imagine that an alien civilization would
want to do the same with us, if they won the war against us. This is essentially us attributing human tendencies to aliens, who may or may not have developed the capacity for such things. Bacteria don't have emotions. Why would aliens?
An alternate idea suggests aliens are among us, shape shifting to blend into the crowd, mating with our kind, essentially mingling in. How this might actually work is never discussed. There is also a huge market for horror movies showing humans as incubatory vessels for alien babies.
Our earth produced carbon-based life-forms. Carbon works because with a valency of four, it is tempted neither to gain nor to lose electrons, but to form perfectly covalent bonds between atoms. Structure-wise, the tetrahedral shape formed by the four bonds per atom is pretty stable. Silicon has the same general properties, being just below carbon in the periodic table, which is why it works well for artificial body parts and implants, with the added advantage that it's easier to manipulate than carbon. It would make sense that alien civilizations are either carbon or silicon-based, but why would they have the exact same anatomy as us, allowing for mating or incubation? We can't even mate with other primates from earth.
My personal opinion? Any aliens that come to earth will probably be some kind of virus. They will probably be as weird as, if not weirder than, mushrooms. And they will probably end up killing us, but not because they want to; it will just be a by-product of their existence.
