system
Given the following post, respond as if you're commenting on Reddit:
human
[sci fi in general] Why is it always assumed that if belligerent aliens could reach earth we wouldn't have a chance?

I can get behind the idea of Aliens devloping FTL technology but what if that's what they put their entire planets resources into and kinda just left their weaponry at lets say, just above chemical-projectile weaponry level - sure, they're not like an adversary we have ever fought before, but why do we instantly assume they have laser death rays and stuff?
gpt
Interstellar travel requires solutions to problems that are far, far beyond our capabilities; a civilization that is able to do that would have technology that outpaces is in every imaginable way, by necessity.

For example, space debris. One of the bigger issues with putting something in orbit around Earth is that there's a bunch of stuff floating around, moving at very fast speeds, and if one of those things crashes into your vehicle, it could very well cause a catastrophe.

Now imagine that you're traveling at a considerable fraction of the speed of light. Now, a single grain of sand is a doomsday weapon to your vessel, just because of the speeds involved. An interstellar vessel needs to solve for that, which means they will have durability that makes our weapons look like squirt guns.

The ability to accelerate something to a high fraction of the speed of light also allows for some very high-impact weaponry. They don't need laser guns and death rays when they can just throw a rock at us at six-hundred million miles per hour. They could cause an extinction-level event trivially.