Contacting extraterrestrials may be better done with X-rays than by radio

OPINION IS DIVIDED on whether Homo sapiens should announce its presence to the universe by broadcasting messages to any putative extraterrestrials who may be listening, or should keep schtum, for fear of attracting unwanted attention. But if attempts at contact are to be made at all, then they might as well be done properly. Past efforts, including one in the 1970s to a star cluster 25,000 light-years away and another in 2017 to a planet a mere 12 light-years away, have used radio. Hang Shuang a...