The idea wasn't Cixin's. E.g., https://www.researchgate.net/profile/Alan-Penny/publication/235358985_The_SETI_Episode_in_the_1967_Discovery_of_Pulsars/links/00

The idea wasn't Cixin's. E.g., https://www.researchgate.net/profile/Alan-Penny/publication/235358985_The_SETI_Episode_in_the_1967_Discovery_of_Pulsars/links/00b7d536a2475d414d000000/The-SETI-Episode-in-the-1967-Discovery-of-Pulsars.pdf https://www.researchgate.net/profile/Alan-Penny/publication/... refers to speculation as early as 1967 that it might not be a good idea to answer that particular phone. Here's a later article from 2010: https://www.sciencedirect.com/science/article/abs/pii/S0094576510000779 https://www.sciencedirect.com/science/article/abs/pii/S00945...