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?
Let’s assume there is some advanced civilization that doesn’t want competition and kills any aliens it finds. Would it make more sense for them to wait for an alien race to develop technology and be on the edge of being a threat before they take action, or would they just destroy the biosphere of any planet they find that could eventually evolve intelligence? My bet is they wouldn’t wait around for a threat to appear, they would prevent it from forming in the first place. With that in mind, we are on the verge of being able to detect if nearby exoplanets could support life. A much more advanced race should be able to do this for every star in a wide area around it, if not the entire galaxy.
Earth has had life for about 3.7 BILLION years. It should have been detectable for most of that. The Milky Way is about 100,000 light years across which means an advanced civilization anywhere in our galaxy should have known that earth supports life for basically its entire existence.
So we are left with three possibilities: Advanced aliens exist and don’t care Advanced aliens exist but are waiting for us to be a threat before doing anything Or advanced aliens don’t exist.
I find option two to be very unlikely.
This isn’t the only problem with dark forest theory though. If life is common enough that intelligence pops up everywhere and competition for resources ensues then no matter what kind of FTL travel you may or may not develop it is inevitable that you will eventually run into a civilization more advanced than you are. Unless you can instantly occupy the entire universe at once, someone somewhere will have been far enough away to develop more than you by the time you met then. In such a case you want to be seen as a nice neighbor, and not a locust, or you risk extermination.
As to your point of not being able to look for life across the galaxy from a single solar system, I think you vastly underestimate the power of technology. We already have plans for how to survey every star system in the galaxy. The telescopes required are just several orders of magnitude bigger than our current best. Making them would be an economics problem, not a physics or engineering problem. But if a race is at the point where they can destroy a biosphere from light years away they are necessarily at the point they can build those telescopes.
Option 4: Advanced aliens killed the dinosaurs, and they’ll kill us once they notice us. But maybe they only check once each galactic year?
Option 5: Advanced aliens killed the dinosaurs, but their civilization fell into ruin.
Option 6. The dinosaurs destroyed the advanced aliens, but one rock got through and fatally damaged their society as well
Ha, I love it!
You might like Deathworlders, specifically the “Salvage” portion of the story
Given the size of the rock that killed the dinosaurs it seems pretty far fetched that aliens would have done that. It’s too small. They would have had to specifically wanted to kill most life but not all of it. When you’re talking about eliminating threats from interstellar distances you go with overkill. You hit somewhere hard enough to rip off the crust and make the planet molten again.
Now if you want to say aliens saw dinosaurs as a dead end path for evolution and hit the reset button that would at least make some sense.
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?
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.
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.