[patentatt]

The precision it would take to launch an unguided rock from one solar system to another and hit a particular target makes that seem unlikely. Just imagine how many different gravitational forces you’d have to account for over such a long period of time! Depending on how fast you can throw it, you probably have to account for gravitational masses that don’t yet exist or would change significantly before your rock got close. It would be truly impressive. But any civilization worth bombarding like that would also probably be able to protect against that threat model, right? It seems that detection and mitigation are at least theoretically within our grasp already (I’m going to cite the movie Armageddon here), and we pose absolutely zero threat to a civilization in a distant solar system.