Even if we somehow manage to destroy ourselves, we’ve been sending radio signals into space (purposefully or not) for over 100 years, since Marconi sent a transatlantic radio message in 1901. Most likely, the ability of civilizations to extract the Morse code letter “s” from the background noise of the universe will effectively impossible. Still, we’ve been beaming radio, radar, and TV transmissions for quite a while.
If we destroy ourselves, our radio, TV, and some internet messages will still be traveling through space. Potentially to infect another civilization with our insanity.
From the movie Men in Black
Kay: That is a lot of fun. It’s a universal translator. We’re not even supposed to have it, and I’ll tell you why… Human thought is so primitive it’s looked upon as an infectious disease in some of the better galaxies. That kind of makes you proud, doesn’t it? huh?
The only way to prevent human insanity from spreading throughout space would be to create a black hole over 100 light years in diameter. There are 180+ notable stars with a 100 lightyear distance from Earth. We’d have to destroy all of them (and any life on planets around any of them.
Not that we could do so at this point.