Aliens
Okay, so you don’t wear a tin foil hat, but bear with us. Most scientists agree that the probability of extra terrestrial life is pretty high. Also, it’s most likely more advanced than us. It is for precisely this reason that people like Stephen Hawking and Elon Musk have advocated against sending messages into space via the SETI program (Search for Extraterrestrial Intelligence). If they’re smart enough to understand our message, they’re either as smart as us…or a lot, lot smarter. The more probable scenario being the latter.