Lazs, if scientists sent such messages out into the universe, I can absolutely and unequivocably say that only humans would hear it, and probably be pissed off too.
There is no evidence of there being anything other than what we know here on Earth, far as what's out there. When men first stepped on the moon surface, NASA scientists didn't really know what would happen, they didn't trust Earth physics to behave there as it does here. There was genuine concern of anti matter possibilities happening there where man was involved, going to an alien lunar surface (even it being our own Moon.) No one knew for sure. They didn't take anything for granted.
Les