The great Italian physicist, Enrico Fermi, called it a paradox. If life is not unique to Earth, and with billions of stars in just our own galaxy, then there must be many millions of Earth-like planets out there populated by intelligent beings. So why haven’t we seen them?
Some of the finest minds in science – and science fiction – have since tried to solve the “Fermi paradox”, but as experts in extraterrestrial life gathered this week at the Royal Society, the greatest question of all remains unanswered: are we alone?
It is one thing of course to be able to detect alien lifeforms on another planet and another to find that there is intelligent life that can travel or communicate through the vast distances of interstellar space.
The two-day conference brings together experts in the various scientific disciplines involved in assessing whether alien lifeforms could exist, what they might look like and how we should attempt to communicate with them if they ever make contact with us.
Frank Drake, the veteran American astronomer who was one of the first to conceive of the idea of a coordinated search for extraterrestrial life (SETI), will today [tuesday] present an upbeat assessment of the chances of finding a signal from space that indicates the existence of intelligent aliens.
Professor Drake famously devised an equation nearly 50 years ago for calculating the potential number of planets in the Milky Way galaxy suitable for life, but he now believes we may have seriously underestimated the potential places in space where life may exist.
“The number of habitable planets in the Milky Way is very probably much larger than we have believed in the past. A realistic picture should include the contributions to habitability of deep atmospheres, thick ice layers, even the solid surface itself, all of which can lead to life-supporting near-surface temperatures,” said Professor Drake.
“Even the very numerous red dwarf star planets may be rendered habitable by a substantial atmosphere or by an eccentric orbit…almost all of the Milky Way becomes a suitable search target,” he said.
The fact that we have not detected any extraterrestrial signals of intelligent life after nearly half a century of listening with powerful radio telescopes should not dissuade us from further searches with more sophisticated instruments than we have used so far, perhaps basing these new tools from space itself, he said.
“This demands a very powerful search system which can search many stars at the same time, at many radio frequencies, and is continuously available, if possible,” Professor Drake said.
“Looking to the future, SETI projects would be far more sensitive and comprehensive if carried out from the far side of the Moon, and ultimately at a gravitational focal point [midway to] the Sun,” he said.
If we do detect signals of extraterrestrial intelligence, one question posed by scientist attending the conference is how to cope with the public response. Will it result in fear, mass panic and riots?
Professor Albert Harrison of the University of California, Davis, believes this is unlikely, based on what he calls “historical prototypes”. In any case, social policies could be used to ease humanity into the “postcontact” era, he said.
“Many people already believe that extraterrestrial intelligence exists and are confident of their own ability to withstand the discovery but doubt other peoples’ abilities to cope,” Professor Harrison said.
“It is easy to imagine scenarios resulting in widespread psychological disintegration and social chaos, but historical prototypes, reactions to false alarms and survey results suggest that the predominant response to the discovery of microwave transmission from light years away is likely to be equanimity, perhaps even delight,” he said.
ET might of course by simple microbes, in which case we will have to go out looking for them, using much the same tools that we have used to search for fossilied microbial lifeforms on Earth.
Professor Colin Pillinger of the Open University, who was the inspiration for the ill-fated Beagle 2 probe to Mars, said that it will not be enough to rely on what we know about life on Earth if we are serious about the search for extraterrestrial lifeforms on other planets.
“More than 70 years ago it was recognised that certain biologically derived molecules survive processing in the geosphere, after the demise of their host, so that features of their structure are little or unchanged after millions of years,” Professor Pillinger said.
“These compounds are thus indicators of the existence of living organisms in Earth’s early history. Such observations led to the idea that ‘carbon skeletons’ as ‘chemical fossils’ could answer questions regarding when life on our planet began,” he said.
“If we are to detect life beyond Earth by comparable methods it will be necessary to delve more deeply into the makeup of organic matter found in space. Chemical methods will need to be more subtle,” Professor Pillinger said.
And then there is the question of what ET will look like. Darwinists believe that alien life on another planet will be subject to the same evolutionary rules that have shaped life on here Earth. This means they might look surprisingly similar to us, according to Professor Simon Conway Morris of Cambridge University.
“It is difficult to imagine evolution in alien biospheres operating in any manner other than Darwinian. Yet, it is also widely assumed that alien life-forms will be just that, alien, strange, un-nerving and probably repulsive. I suggest two opposites, both of which make our blood run cold,” Professor Conway Morris said.
“The first, and actually extremely unlikely, is that alien biospheres will be strikingly similar to the terrestrial equivalent and that in such biospheres intelligence will inevitably emerge,” he said.
“The reasons for this revolve around the ubiquity of evolutionary convergence, the determinate structure of the Tree of Life, and molecular inherency. In reality Darwin only explained the mechanism but failed to grasp the predictability.
“But if something like a human is an inevitability why do I also claim that the first possibility is extremely unlikely? Simply, because the other possibility is actually the correct answer. We and our biosphere are completely alone. So which is worse? Meeting ourselves or meeting nobody?” he said.