I realize you can just answer, “mysterious aliens beyond our understanding,” but why would a space probe have a mandate of either talk to a whale for 30 seconds or destroy Earth and disable everything in its path on the way to Earth?
Why? What does that achieve?
Yeah, even Wikipedia goes with “probably extinct.” How sad.
Anyway, it’s an amazing book. There was also a radio series which is decent (I believe you can get it on the Internet Archive) and Stephen Fry did a follow-up TV series around 15 years go.