But as rain poured from the heavens outdoors, scientists, astronomers, artists and musicians hunkered down in the warm sitting room of the private home to swap ideas on how to chat with E.T. -- if he ever calls. And what, if anything, to say.
Seemingly fulfilling every possible cliche -- from a young computer whiz, to a softly-spoken NASA scientist, a professor with a shock of white hair and an excitable Russian -- the group of respectable professionals were earnest in their arcane endeavors.
Mathematical equations filled overhead projection slides, exotic Indonesian gong music rang out and the talk was of complex scientific phenomena and deeply philosophical questions about the nature of human beings and their relationships.
"We are not trying to find the best message or even the most intelligible," said Douglas Vakoch, who led the Paris workshop. In his other incarnation, Vakoch runs the interstellar message group at the Search for Extraterrestrial Intelligence (SETI) institute in the United States.
"I think we should construct thousands of messages in the hope one of them could be understood ... I think there is a reasonable chance we can overcome the barriers between human and extraterrestrial worlds, but maybe we can't."
"Maybe, even if we get a signal from them, their way of conceptualizing will be so alien to us that we just can't."
SETI, a private nonprofit organization sponsored by the U.S. government, NASA and technology giants such as Sun Microsystems, has been monitoring radio signals for the past 40 years in the hope of picking up a transmission from outer space.
"We have to use the tools that we have right now to search for signs of alien life. We are very hopeful," Vakoch said, as he sat in the kitchen of the Paris house.
"We are looking for signals by radio ... but we can't rule out that they may already be trying to contact us and we can't detect them."
But, with computer and other technologies making advances all the time, Vakoch argues it is time to get serious about working out what, if anything, humanity would want to say to an alien civilization.
The assumption is that any signals picked up by SETI will be in radio form and therefore the alien sending the message will likely have similar technology and share our language of physics and maths -- making possible a conversation, of sorts.
And that is where the Paris meeting comes in.
In the house of the late Frank Malina, a U.S. pioneer in jet propulsion, and in the very rooms that some of the early Russian cosmonauts spent time learning English, the assembled artists and scientists put their heads together to brainstorm possible messages.
"Today the focus has been on whether we can explain something about our aesthetic sensibilities. Is there something about art that is either universal or that can be taught, step by step, to another intelligence?" Vakoch said.
Surrounded by walls covered in Malina's kinetic art -- pulses of electric light shining through moving elements -- people from six nations discussed what aspects of the human understanding of art and beauty could be revealed to other beings.
A professor of theoretical computer science suggested using music as a teaching aid to help aliens learn a coded language for cosmic conversations. He suggested employing the strange sounds of Indonesian gongs and gave a demonstration -- once he had worked out how to switch on the tape recorder.
An artist suggested using a rainbow as a metaphor for mankind's unity through diversity; a symbol of peace and a bridge. He would like to transmit the mathematical formula for color wavelengths so that alien beings could create rainbows for themselves.
"Imagine how amazing it would be if we introduced color into an alien species' life for the first time," he said.
Others talked of algorithmic communication or computer systems that mimic human responses.
For Vakoch, all the theorizing serves another useful purpose.
"The truth is we don't know if there is alien life out there, but in thinking about how we would communicate something about our sense of beauty or who we are, we are forced to reflect differently on ourselves and question our basic assumptions," he says.
In discussing alien life and how it may or may not differ from our own, Vakoch says, the differences here on Earth between cultures, ethnic groups, nationalities and the sexes are put into a context which renders them less significant.