Physicist Stephen Hawking has teamed up with a Russian billionaire to launch a new quest to discover life on other planets.
The celebrated scientist has given his backing to Yuri Milner's Breakthrough Initiatives project, which will provide 100 million dollars (£64 million) over the next decade to those searching for extraterrestrial intelligence.
Mr Milner, an entrepreneur who made his fortune through investments in technology companies such as Facebook, said he will harness the innovation of Silicon Valley to scan the skies for signs of life, including searching the entire Milky Way and 100 nearby galaxies
The Breakthrough Listen branch of the project will use the world's finest telescopes to carry out state-of-the-art radio and optical surveys.
Mr Milner called it the "most comprehensive search programme ever", and claimed the project would gather more information in one day than in a year of previous research.
Announcing his support for the project, Professor Hawking said: "I am here today because I believe the Breakthrough Initiatives are critically important.
"To understand the universe you must know about atoms. About the forces that bind them, the contours of space and time. The birth and death of stars, the dance of galaxies, the secrets of black holes.
"But that is not enough. These ideas cannot explain everything. They can explain the light of stars, but not the lights that shine from Planet Earth.
"To understand these lights you must know about life, about minds. We believe that life arose spontaneously on Earth so in an infinite universe there must be other occurrences of life.
"Somewhere in the cosmos, perhaps, intelligent life may be watching these lights of ours aware of what they mean. Or do our lights wander a lifeless cosmos, unseen beacons announcing that here on our rock, the universe discovered its existence?
"Either way, there is no bigger question. It is time to commit to finding the answer to search for life beyond Earth. The Breakthrough Initiatives are making that commitment. We are life, we are intelligent, we must know."
Mr Milner, who was named after the first man in space, Russian cosmonaut Yuri Gagarin, said that all the information gathered by Breakthrough Listen would be open to the public.
As well as using some of the world's most powerful telescopes, he announced that the project would also harness the power of nine million personal computers around the world via the SETI (Search for Extraterrestrial Intelligence) network.
Launching Breakthrough Listen, Mr Milner said: "Today we are launching the most comprehensive search programme ever. Just in one day Breakthrough Listen will collect more data than a year of any previous search.
"The scope of our search will be unprecedented - a million nearby stars, the galactic centre, the entire plane of the Milky Way and 100 nearby galaxies."
The project will use and develop new, powerful software, which will be open-source, while the approach to data would be "transparent, innovative and that uses the problem-solving power of social networks".
Explaining his project, Mr Milner said mankind had only begun to explore the possibility of extraterrestrial life.
He said: "Thanks to Kepler mission it is now estimated that there are billions of potential habitable planets in our galaxy alone.
"As another leader of the search, Jill Tarter, said, if you dip the drinking glass into the sea once and came out without a fish, would you conclude that there are no fish in the sea?
"Breakthrough Listen will dip much more than a glass in the sea, by bringing a completely different scale of technology to the problem."
He added: "Breakthrough Listen takes the search for intelligent life in the universe to a completely new level.
"It is the most comprehensive in scope, it is faster and more sensitive than any previous search and will cover the broadest ever spectrum."