Which 2015 initiative to search for extraterrestrial intelligence did Stephen Hawking help launch?

Stephen Hawking helped launch Breakthrough Listen in 2015.

The initiative was announced on 20 July 2015 at the Royal Society in London by internet investor Yuri Milner, with Hawking and other scientists supporting the project. Backed by $100 million and planned as a ten-year effort, Breakthrough Listen was designed to search for technological signals from intelligent life beyond Earth rather than merely look for signs of simple biology.

Its observing program uses major facilities including the Green Bank Telescope in West Virginia, the Parkes Observatory in Australia and the Automated Planet Finder in California. The project surveys nearby stars and selected galaxies, collecting enormous quantities of radio and optical data for analysis. Its science program is based at the Berkeley SETI Research Center.

A common mix-up is SETI@home: that is a volunteer-computing project that has helped analyze some SETI data, not the 2015 initiative itself. Breakthrough Starshot is another related Breakthrough project, announced in 2016, focused on sending ultra-fast probes toward nearby stars.