LogFAQs > #936113865

As long as we are thinking up reasons for an invasion/anti-human campaign/attacking earth, though, lets see...

-Something just bad is out there. Like maybe someone with interstellar ability eventually went and got into Hollywood's favorite AI scenario and then lost, leaving an automated AI war machine capable of keeping itself functional and everything, but also lacking any sort of ability to have or gain logical circuitry that emulate empathy (such as even "this stuff is interesting and could prove to teach us something useful, so we should leave it be to see what we can learn from it"). You know, automated, cold, self-maintaining and replicating AI death fleets that don't really make new technology much, if at all. They might not need a reason to attack a planet with life on it, especially if they are effectively just malfunctioning warbots on a galactic scale. They find a weird radio source? They flag it is enemy, and attack.

-They don't want the planet. They actually want humanity in some way. We can imagine various versions of this scenario, from it being a small fleet of slave traders that perform raiding warfare attacking and kidnapping humans to sell, to a civilization that outright just needs the population of earth because it has some issue that it desperately needs humans for. This could be anything from needing a sudden and very large population of slave labor to them just being a dwindling race who wants their civilization to persist even if the last of they themselves eventually die off, and forcefully "recruiting" a new race to continue "holding the torch," and deciding that humanity can/should do it (or that we are just the only ones they found nearby). To other reasons, really. You can imagine lots of things.

-Basically the Zerg or Tyranid, except more realistic. I.e. some sort of alien life who has interstellar technology, but whose general mindset is one of consuming other life like the afforementioned fictional threats, and may potentially even have some degree of hive mind aspect to them. For this scenario, the radio waves don't help, as they would also be looking for planets that show oddities and thus likely have life. So the fact that our planet has an atmosphere with oxygen in it would be the bigger beacon to them than our radio waves. As such, this scenario would tend to require that they are still somewhat a fledgeling interstellar race, as they haven't already found the planet and come to consume it.

-They have idealogical reasons that deem humans as dangerous or something that must be destroyed. They don't care about the planet, and can just lob a big rock at it to clean it out and purge the galaxy of whatever they don't like about humanity. In this scenario, we might not even know the truth behind our incoming demise, as we don't have full tracking of all dangerous objects yet anyway and would assume we just missed it. As for why they don't like humanity, there are plenty of possible reasons, ranging from them learning enough about us to decide we are dangerous in some way, to them just having a xenophobic society to where they just don't WANT other aliens around.

-A more "gentle" reason. They want to induct us into their empire or other such thing. And decide that an invasion or show of force is necessary rather than diplomacy. In this scenario, we could expect anything from a bloody war that doesn't care how many people die as long as the rest surrender, to a civil conflict where they show up and demand some form of surrender, swatting away the military and then leadership until we (or they) put someone in charge who does so.

-They appear hostile but are trying to save Earth's life. They have FTL, but something they DON'T have the technology to stop is going to hit the Earth (like the polar pulse from a star going supernova fairly "nearby" or a reasonably large black hole that will enter the solar system shortly and destroy all the orbits), and they care enough about life to try to forcefully relocate as much of it as possible to another planet that is not about to get sterilized. Maybe they don't have enough time to try and learn enough to be diplomatic, and so they are just doing it forcefully.

These are just a few ideas, mind you. I'm sure there are plenty of other various ideas one can imagine for something to want or "want" to attack earth.
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