A mature civilization could probably perform a kinetic bombardment with masses accelerated to a significant value of c. There would be waiting, but there would

A mature civilization could probably perform a kinetic bombardment with masses accelerated to a significant value of c. There would be waiting, but there would be no need to travel here personally. That said, I'm not particularly worried about it either. I suspect we will either have scientific value (independently evolve intelligence, which appears rare) or never pose a real threat to them, assuming learning curves remain exponential for civilizations.