Individually doing atmospheric analysis for every planet in the galaxy is probably an impossible task for a civilisation confined to a single solar system. Listening for signals is something our civilisation already does. If we discover radio signals from a primitive civilisation in the next star system over there’s a non-zero chance we’d panic and try to wipe them out.
That’s the risk that dark forest theory is talking about. Maybe the threat comes from a civilisation dedicated to wiping out intelligent life that just hasn’t found you yet, maybe it just comes from your nearest neighbor. Maybe there’s no threat at all. The risk of interplanetary war is still too great to turn on a light in the forest and risk a bullet from the dark.
And while knowing this, why do we still not choose to just observe and be as quiet/ non existant as possible?
Yeah, that’s a fair point about using a larger meteor. Unless the alien assigned to the task screwed up? Unlikely, yes, but that’s the problem with this kind of speculation. There isn’t really any evidence to examine. Maybe there weren’t any aliens. Maybe there were, and they screwed up! Maybe there were, and they thought what they used would be enough, but a quirk of Earth biology let small mammals survive. Maybe there were two groups of aliens, and the second group interfered enough to prevent full overkill.
Alien shepherds could def be Option 6. These could all be fun sci-fi story prompts!
Able to detect life from a different solar system. Able to send a meteor to exactly hit a specific planet light years away. Yet they screwed up the math on the size?
Screwed up the math, or made a typo when entering the parameters into their computer, or the being in charge was in a hurry and eyeballed it “eh…close enough, let’s do this and go home!”. We’re talking about hypothetical aliens with technology, not gods.
More likely is that there were no aliens, but that’s the boring theory.
Meh, Bob was having a bad day when he was assigned to grabbing an asteroid out of the Kuiper Belt and sending it to destroy life on a planet.
He grabbed the most convenient one that seemed big enough, so he could check the box, and get back to playing Missile Command.
Besides, it’ll take millions of years for any life to recover on that planet, wtf does he care, he’ll be long dead.