That's actually a really good question because there's no way, even with 100% of the sun's mass going into the effort, that we could actually zap everything in the galaxy to death. We'd have to instead have a signal so depressing that, as soon as a species decodes it, they'd be guaranteed to start sending out a similar signal and destroy all life within zapping range. A sort of interstellar bird box, written and directed by Todd Solondz.