Stephen Hawking has long made his concerns about the search for extraterrestrial life clear. But after his appearance with Russian billionaire Yuri Milner on Monday to announce Breakthrough Listen, the new $100 million initiative looking for signs of intelligent life, the famous physicist seems to have at least partially reconsidered.

Hawking famously revealed his worry that any aliens advanced enough to contact earth would be “looking to conquer and colonize whatever planets they could reach” during a 2010 episode of the miniseries Into the Universe with Stephen Hawking. And he clearly hasn’t changed his mind completely. “If you look at history, contact between humans and less intelligent organisms have often been disastrous from their point of view, and encounters between civilizations with advanced versus primitive technologies have gone badly for the less advanced,” he told reporters at the Breakthrough announcement. “A civilization reading one of our messages could be billions of years ahead of us. If so, they will be vastly more powerful, and may not see us as any more valuable than we see bacteria.”

Still, he said, the initiative is of special importance in a moment when humanity’s achievements in space are in the spotlight. “We are alive. We are intelligent. We must know,” he said of the search for life beyond earth.

Breakthrough Listen will provide funding explicitly for the search for extraterrestrial life, scanning the million stars closes to Earth and portions of 100 neighboring galaxies but not for sending messages or signals to communicate with that life, an important distinction for scientists like Hawking, who are concerned with the possible consequences of contact. Instead, a second program, Breakthrough Message, will host a competition in which anyone can submit ideas for potential interplanetary messages.

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