Re: Dyson sphere protection
OK, let's assume they're actually a threat. I still say that they're not and that Michael is correct above, but let's just assume they are.
So: I'll build a bunch of telescopes and "lasers" on the outer layer of my swarm, and I'll use about 0.000001% of my available power to continually scan the entire sky using automated systems, looking for threats. As a bonus, this system also gives me super awesome astronomy capabilities because it means I'm doing a continual full-sky survey. And I'm not even going to notice the resources it uses. So I'm actually really happy to do this even though I don't consider these objects a threat.
And if I find any threats, I'll use 0.001% of my available power to vapourise them with my "lasers" before they get within a few AU of any of my important stuff.
And to deal with the really big once-in-a-million-year rogue planets, I'll start working on the infrastructure for a stellaser so that I can put 10% or 20% of my available energy into vapourising stuff if I need to.
Biting the hand that feeds IT
