Statistically speaking, there is every chance that life could exist somewhere other than Earth, although it is still very difficult to define the shape, according to a science conference Monday in London.

“There is no official evidence that life exists elsewhere, but there is a very high probability that it exists,” said Baruch Bloomberg, an astrobiologist at Fox Chance Cancer Center in Philadelphia.

“I am convinced that the present generations have an excellent opportunity to witness the discovery of life outside Earth during their lifetime,” said Martin Dominic, an astronomer at the University of St Andrews in Scotland.

Life may have started on Earth thanks to carbon particles and dust coming from interstellar space, recalls Pascal Erinfrond, an astrochemist at George Washington University in the US capital.

If so, then “the first building blocks of life – as we showed us to Earth, ought to be widespread in other planetary systems in the Milky Way and in other galaxies,” this scientist suggests.

The British Royal Society, one of the cradles of modern science, took the matter seriously enough to dedicate a two-day symposium to it on the occasion of its 350th anniversary.

It was not so much about giving a definitive answer to the existence or non-existence of aliens as it was about painting a picture of our pursuit of another life, and asking about the impact of such a discovery on humanity.

The President of the Royal Society, Lord Reese, stressed that we must admit our ignorance at this time. “We don’t even know how life arose on Earth, let alone whether we think it is widespread (elsewhere) or not, or where to look for it,” he said in an interview.

Thanks to increasingly sophisticated observation tools, in particular the Hubble Space Telescope, since 1995 astronomers have discovered more than 400 exoplanets outside of our solar system.

One of these planets could host life, but none has been discovered that benefit from the favorable conditions of our blue planet.

Earth is actually at a sufficient distance but not too far from the sun that water can be found in abundance in liquid form.

If life forms exist anywhere other than Earth, they are unlikely to come close to what science fiction films, which always resemble their human creatures, are unlikely to come close.

For Albert Harrison, a psychologist at the University of California, Davis, the first alien discovered was likely to be microscopic in size.

Even within our solar system, bacteria can be detected in the vault of Mars, on Jupiter’s satellite Europa or even on Saturn’s moon, Enceladus. These last two stars can host oceans under thick ice caps.

However, other scholars believe that the emergence of life is a combination of conditions that are not about to be repeated.

“In my opinion, the origin of life is pure luck,” said Simon Conway Morris, professor of paleontology at Cambridge University.

“I fear we are completely alone … nothing at all,” explains this scientist.

And if aliens had to contact us, there was nothing to say that they would have the beautiful eyes of ET, the charming antics from Steven Spielberg: they might as well be “aggressive and unpleasant,” he notes.