The Great Filter is the idea that, in the development of life from the earliest stages of abiogenesis to reaching the highest levels of development on the Kardashev scale, there is a barrier to development that makes detectable extraterrestrial life exceedingly rare. The Great Filter is one possible resolution of the Fermi paradox.
https://en.wikipedia.org/wiki/Great_Filter
The Fermi paradox is the discrepancy between the lack of conclusive evidence of advanced extraterrestrial life and the apparently high likelihood of its existence. As a 2015 article put it, “If life is so easy, someone from somewhere must have come calling by now.”
https://en.wikipedia.org/wiki/Fermi_paradox
Personally I think it’s photosynthesis. Life itself developed and spread but photosynthesis started an inevitable chain of ever-greater and more-efficient life. I think a random chain of mutations that turns carbon-based proto-life into something that can harvest light energy is wildly unlikely, even after the wildly unlikely event of life beginning in the first place.
I have no data to back that up, just a guess.
Well, “relatively cheaply” is a hard standard to nail down. I would say “no”, though. Antimatter is very expensive to manufacture and store and you’re going to need a lot of it. All of the energy that comes out of an RKV hitting its target has to be put into it in the first place, probably several times over given the inefficiencies likely inherent in the process.
Fair enough, guess it depends on how many resources they’re willing to sink into first strike capability. Maybe a strongly expansionist civilization would have such a more efficient use of resources it would quickly catch up to a dark forest predator trying to wipe them out. Like a swarm of piranha eating a shark.