A Russian entrepreneur has launched the biggest and most expensive search for alien life ever, backed by famous scientists including Stephen Hawking and Frank Drake.

Yuri Milner, who funds a range of science prizes, has launched a $100 million project called Breakthrough Listen that will give scientists some of the most promising chances to find human life in the universe.

He will also launch another project called Breakthrough Message, which will work together to create a message that can be sent to aliens. The best messages will share a reward of $1 million.

The mission to decide exactly what to say has been a difficult one — some cosmologists have worried that plans to beam messages could spell doom for humanity.

The project will give those scientists that are looking for life elsewhere in the universe better access than ever to telescopes and computing power, which will be used to try and find life elsewhere in the universe.

Hawking said that it differentiated itself from previous initiatives because of its increased resources — including extra time with telescopes and more data processing capabilities.

He also warned against getting in touch with any extraterrestrial life that is found. Confrontations between more and less advanced civilisations have often gone wrong, and aliens could be billions of years ahead of us and so see us as no more valuable than we see bacteria.

Other members of the group of high-profile scientists backing the mission said that they didn't want to send a message for fear of upsetting people who worry that aliens might become enraged by our doing so. Using funds to send messages would also be a waste of limited funds, said Frank Drake.

But Ann Druyan, who is leading the work on Breakthrough Message, said that the work to decide what to say to aliens is valuable even if it doesn't actually get sent. It will help humanity think about itself and work out its place in the universe, she said.

Milner said his motivation is his belief that other civilizations could teach us how to handle challenges such as allocating natural resources — and that we might learn from finding that there is no other life.

"If we're alone, we need to cherish what we have," he said. "The message is, the universe has no backup."

The only previous major search for life was known as the Search for ExtraTerrestrial Intelligence, or SETI. Globally, less than $2 million annually is spent on SETI, said Dan Werthimer, an adviser to Milner's project and the astrophysicist who directs the SETI@home project affiliated with the University of California in Berkeley.

Today, due to improvements in technology, including in computing power and telescope sensitivity, $100 million will go much farther than in the early 1990s, the last time SETI had significant funding, scientists said.

In one day, the project will collect more data than a year of any previous search, Milner said.

All of the data will be made available to the public, and all of the software developed during the search will be made open source so that anybody can use it. “More data will be open than ever in the history of science,” Milner said.

As such, it will join up with SETI@Home, which hooks personal computers together so that their spare computing power can be contributed to the search through data.

The advances allow scientists to monitor several billion radio frequencies at a time, instead of several million, and to search 10 times more sky than in the early 1990s.

But any signals the scientists detect will likely have been created years ago, perhaps even centuries or millennia earlier. Radio signals take four years simply to travel between Earth and the nearest star outside our solar system.

The advances allow scientists to monitor several billion radio frequencies at a time, instead of several million, and to search 10 times more sky than in the early 1990s.

But any signals the scientists detect will likely have been created years ago, perhaps even centuries or millennia earlier. Radio signals take four years simply to travel between Earth and the nearest star outside our solar system.

In 10 years, with his $100 million, Milner figures scientists can listen for radio transmissions in the Milky Way galaxy, plus the 100 nearest galaxies.

One of the biggest costs lies in booking time at radio telescopes, including at Australia's Parkes Observatory in New South Wales and the Radio Astronomy Observatory in Green Bank, West Virginia. Milner plans to book about two months a year at each site, a boon to scientists who normally might get two days a year on the telescopes.

The team, led by scientists such as Peter Worden, who until earlier this year directed the NASA Ames Research Center, will organize the radio signals they find, make the data public, and examine the data for patterns.

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The goal lies less in understanding the signals than in establishing whether they were created by intelligent life rather than natural phenomena.

Scientists say the fact that humans have developed radio signaling makes it a good bet that others may use it as well.

"It doesn't tell you anything about the civilization, but it tells you a civilization is there," said Frank Drake, who with Carl Sagan sent the first physical message into space in 1972, the Pioneer plaques on board the Pioneer 10 US spacecraft. An adviser to Breakthrough Listen, Drake is also chairman emeritus of the SETI Institute.

In addition to checking for radio signals, Breakthrough Listen will hunt for light-based signals using a telescope at the Lick Observatory in California.

Milner announced the initiative in London accompanied by scientists such as Stephen Hawking, the physicist and author. Hawking holds an advisory role on the project.

A physicist by training, Milner joins many successful entrepreneurs and investors with an interest in space, notably SpaceX Chief Executive Elon Musk, who has said he would like to colonize Mars one day.

Milner made his fortune through a series of early investments in successful startups, like Facebook. He has used some of that money to fund science prizes including the Breakthrough Prize — a set of awards that recognise achievement in life sciences, fundamental physics and maths.

"It's the most interesting technological question of our day," Milner said in an interview, noting that he became fascinated by the notion of extra-terrestrial life after reading astrophysicist Carl Sagan's Intelligent Life in the Universe as a 10-year-old in Moscow.