Assuming there is prolific amount of extraterrestrial life out there, alien invasion is still very very unlikely.
Civilizations that have a tendency to be violent/imperialistic will also be likely to be fighting constant battles for power on their own planet and remain balkanized and uninterested in space emigration.
Space travel is super expensive, monetarily yes, but also inherently in terms of resources and being power. It’s very unlikely that space emigration would be more cost effective than whatever it takes to fix any kind of domestic problem aliens might otherwise try to escape.
Generally any quality that would be needed for an alien invasion to occur would make it less likely that the alien civilization would resort to such. It would just require way too many unlikely coinciding set of qualities/circumstances to make such a thing a likelihood. Such as a really random and specific religious cult. Or a biology than happens to be friendly to interstellar spore travel.
We have no way of really knowing the true capabilities and motivations of an alien society which had the ability to make it to our planet.
We can’t say we wouldn’t be “out of the loop” to the extent that dogs watching television are with regard to the politics behind network TV advertising.
Well, if it is that expensive, sooner or later it will be the ultimate way of showing the whole universe how filthly rich someone is. And there’ll be a wealth muscle competition about who gets there first. We’re doomed!
Strange debate, I’d have thought that the premise that being invaded by aliens is pretty unlikely would have been the default position myself, with little need of explanation. Though there is a bit of scope for interpretation there, since your premise is so vague.
Is Earth getting invaded by aliens pretty unlikely? All the data would point to yes, and by ‘data’ I mean the fact that there hasn’t been a single alien invasion (excluding Jesus) in the whole of recorded history. That’s makes the chance of it hapenning next week pretty small IMO. Being wiped out by a large asteroid is much more likely.
But you don’t actually specify that it would be us that has to be invaded. Somebody, somewhere, in the whole of the universe over many trillions of years conducting an invasion of a non-native terrestrial body currently inhabited by a different sentient species is a near certainty. The most obvious scenario would be two planets in a single solar system evolving with different sentient species with similar environmental requirements. In this case an invasion would be relatively inexpensive compared to the benefits of gaining a second planet, especially if there is a technological disparity (which is nearly guaranteed I would think).
Is this scenario unlikely? Yes. But the universe is a big place.
I think that aliens have been to Earth, but to quickly look around, check us out and leave. They now not to fuck with human beings. If I see a little Green Man, I am going to kill it. If a flying saucer came to Earth, the military would try to shoot it out of the sky. The human race is full of war, violence, greed, insanity, religiousity and stupidity. If we weren’t, we would be in deep space by now. Our true enlightment hasn’t come and may never will.
Second point, I believe that the Earth is in a vast unpopulated area of space. Very isolated with no other habitable planets for numerous light years. Like a small town in the middle of a vast desert, Earth is the Baker, California of the Universe. Earth is also an insignificant planet in the grand scheme of things, revolving around a dinky star we call the Sun.
Humanity is the only data you have to go on. We’re on the verge (perhaps within the next 1000 years) of interstellar space travel, and I don’t see any indication that we’d not invade an alien planet. Probably we’d convince ourselves it will be for their own good.
Or we just wouldn’t care. After all we already know that we care a lot less about people suffering in foreign countries that don’t look like us or speak our language. An alien will look nothing like us and won’t trigger our empathy/sympathy emotions at all, unless they’re extremely lucky and look like cuddly kittens.
And on another level, why should we care? Are we morally impelled to look after all scentient life or just look after our own species? How can we take the gamble that a currently friend species might not turn around later and eliminate us? Shouldn’t we just kill everyone else as soon as possible?
Why does it have to be super expensive to invade a planet? Beyond getting there you don’t need much really. Just drop a few asteroids on them. If you have the tech to get to another planet nudging a few asteroids on to them shouldn’t be too difficult. Once the dust settles you can invade with a handful of people and put your flag in the ground.
This is the least convincing point. Are imperialistic countries here more likely to break up due to civil war? What if one empire conquers the entire planet and sets its sights elsewhere? Why can’t they get along fine and direct their violence outwards? Like space locusts.
I agree that getting resources from the Earth would be more expensive than elsewhere. If you need water or metal there are much easier targets. Here are reasons why they would bother, as far as I can see: our type of atmosphere / temperature range is in high demand for colonization, they have a religious streak and want to convert/kill us, or their attitude toward other sentient life is to shoot first and ask questions later.
Unless your view of nearby is extremely limited, then this is something you don’t know. And in fact, there might yet also be simple alien life forms on Mars. Some people have argued that if that is the case then we should stay completely away for fear that they should be wiped out by Earth-based forms. I find it unlikely that the all nations and private individuals could agree to such a policy for the next many centuries. And actually I see no reason to assume that an alien civilization would be any more ordered than human. I imagine an alien intervention on Earth would begin with individual aliens on their own initiative starting to harvest resources or go here and do whatever they find interesting.
I didn’t say civil war as a specific method of break up, but of all the great empires Earth has seen, all have inevitably broken up. The only lasting unifications we’ve seen have been for peaceful reasons, not through conquering.
This and extreme patriotism (which is essentially also a fanatic religion) are the only reasons I could see for alien aggression.
Regarding the OP, only # 2 matters at all. The vast expanse of space is the only barrier we have that has prevented alien invasion. Fortunately, it is a major barrier. A huge barrier.
I will say though, that while an alien invation is extremely unlikely -
the chance of an alien invation = the chance of an alien encounter.
No alien is going to fly to earth to say hello and then be on their way. If they come here it will be to inhabit the planet, displacing/killing humans and anything in their way. It will be a one way trip for them, since it will probably have takens them hundreds or thousands of years to make that trip.
Similarily, if humans fly to another planet someday it will be to colonize it. Two points to this:
Either the aliens are advanced enough they are a possible threat and must be eliminated.
The creatures are not as advanced as us and we won’t care about their culture/language/feelings. Similar to how we treat dolphins today.