“Rather than asking how many civilisations may exist now, we ask ‘Are we the only technological species that has ever arisen?" explains coauthor Woodruff Sullivan from the University of Washington.
“This shifted focus eliminates the uncertainty of the civilisation lifetime question and allows us to address what we call the ‘cosmic archaeological question’—how often in the history of the universe has life evolved to an advanced state?”
Using the new exoplanet data that Kepler collected the Sullivan and his counterpart Adam Frank decided to take the standard model of searching for life and twist it round.
This meant that their equations were not trying to discover the probability of advanced life forming but instead asking how likely is it for us to be the ONLY civilisation that the Universe has ever produced.
What they found was that human civilisation is likely to be unique in the cosmos only if the odds of a civilisation developing on a habitable planet are less than about one in 10 billion trillion, or one part in 10 to the 22th power.
“One in 10 billion trillion is incredibly small,” says Frank. “To me, this implies that other intelligent, technology producing species very likely have evolved before us."
"Think of it this way. Before our result you’d be considered a pessimist if you imagined the probability of evolving a civilisation on a habitable planet were, say, one in a trillion. But even that guess, one chance in a trillion, implies that what has happened here on Earth with humanity has in fact happened about a 10 billion other times over cosmic history!”
There is however some bad news, which is that while alien life probably did exist in the Universe, the chances of us ever meeting them are almost never.
Why? "Even if there have been a thousand civilisations in our own galaxy, if they live only as long as we have been around—roughly ten thousand years—then all of them are likely already extinct." explains Sullivan.
"And others won’t evolve until we are long gone. For us to have much chance of success in finding another "contemporary" active technological civilisation, on average they must last much longer than our present lifetime.”
“Given the vast distances between stars and the fixed speed of light we might never really be able to have a conversation with another civilisation anyway,” said Frank. “If they were 20,000 light years away then every exchange would take 40,000 years to go back and forth.”
NASA's Most Famous Images:
Edward H. White II, pilot of the Gemini 4 spacecraft, floats in the zero gravity of space with an earth limb backdrop circa November 1965.
Kinescope images of astronaut Commander Neil Armstrong in the Apollo 11 space shuttle during the space mission to land on the moon for the first time in history on July 20, 1969
The ascent stage of Orion, the Apollo 16 Lunar Module, lifts of from its descent stage to rendezvous with the Apollo 16 Command and Service Module, Casper, with astronaut Thomas Mattingly aboard in lunar orbit on 23rd April 1972.
Five NASA astronauts aboard the Space Shuttle Atlantis look out overhead windows on the aft flight deck toward their counterparts aboard the Mir Space Station in March of 1996.
Photograph of the Milky Way Galaxy captured by NASA's Spitzer Space Telescope. Dated 2007.
The exhaust plume from space shuttle Atlantis is seen through the window of a Shuttle Training Aircraft (STA) as it launches from launch pad 39A at the Kennedy Space Center July 8, 2011 in Cape Canaveral, Florida.
A United Launch Alliance Delta 4 rocket carrying NASA's first Orion deep space exploration craft sits on its launch pad as it is prepared for a 7:05 AM launch on December 4, 2014 in Cape Canaveral, Florida.
A military pilot sits in the cockpit of an X-15 experimental rocket aircraft, wearing an astronaut's spacesuit circa 1959.
Echo 1, a spherical balloon with a metalized skin, was launched by NASA on 12th August 1960. Once in orbit the balloon was inflated until it reached its intended diameter of 30 metres and it was then used as a reflector to bounce radio signals across the oceans.
Four views of Earth rising above the lunar horizon, photographed by the crew of the Apollo 10 Lunar Module, while in lunar orbit, May 1969.
American geologist and Apollo 17 astronaut Harrison Hagan Schmitt stands next to the US flag on the surface of the moon, during a period of EVA (Extra-Vehicular Activity) at the Taurus-Littrow landing site, December 1972.
The space shuttle 'Enterprise' (NASA Orbiter Vehicle 101) makes its way along Rideout Road (Alabama State Route 255) to the Marshall Space Flight Center near Huntsville, Alabama, 15th March 1978.
A crowd of people, viewed from behind, watch the launch of the first NASA Space Shuttle mission (STS-1), with Columbia (OV-102) soaring up into the sky, leaving a trail of exhaust smoke, in the distance from the launchpad at the Kennedy Space Center, Florida, USA, 12 April 1981.
Astronaut Bruce McCandless II photographed at his maximum distance (320 ft) from the Space Shuttle Challenger during the first untethered EVA, made possible by his nitrogen jet propelled backpack (Manned Manuevering Unit or MMU) in 1984.
Aerial shot of the launch of Space Shuttle Discovery (STS-41-D) as it takes off, leaving a trail of exhaust smoke, from Kennedy Space Center, Florida, USA, 30 August 1984.
Two technicians inside a Space Shuttle external tank, circa 1985.
An astronaut's bootprint leaves a mark on the lunar surface July 20, 1969 on the moon. The 30th anniversary of the Apollo 11 Moon mission is celebrated July 20, 1999.
Astronaut Charles Moss Duke, Jr. leaves a photograph of his family on the surface of the moon during the Apollo 16 lunar landing mission, 23rd April 1972.