THIRTY-FIVE years ago, a gold-plated record was lofted into the cosmos with a greeting card for the first extraterrestrials who found it. The golden plaque, attached to the Voyager spacecraft, was etched with a medley of Earth sounds, from a baby’s cry to musical selections ranging from a Bach fugue to Chuck Berry’s upbeat “Johnny B. Goode.” Not long after the probe was launched, a psychic played by Steve Martin on “Saturday Night Live” revealed that aliens had promptly delivered this urgent four-word response: “Send more Chuck Berry.”

The news last week that a concerted scientific search for extraterrestrial intelligence by the SETI Institute in California has resumed raises fundamental questions: If we made contact, what would we say? And what answers would we anticipate?

The first words of a conversation initiated by aliens were immortalized in a 1953 New Yorker cartoon by Alex Graham: “Kindly take us to your President!” Our own greetings have already been inadvertently transmitted, if not delivered, in random radio broadcasts that are just now reaching roughly 100 light-years away. Among the first images that escaped the earth’s atmosphere was a 1936 telecast of the Nazi-produced Olympics.

If intelligent life exists elsewhere in the universe, two giant hurdles would have to be overcome to have a conversation. Dialogue would probably be intergenerational — a response to a message sent by us would likely be delivered to a distant descendant. “You should think of METI messages” — referring to messaging to extraterrestrial intelligence rather than searching — “as being like time capsules, rather than like telephone calls,” said Michael W. Busch of the National Radio Astronomy Observatory at the University of California, Los Angeles.