Reports concerning the probable presence of alien life and our opportunities to identify it usually carry an optimistic tone. We frequently receive updates suggesting that a discovery could happen at any moment. The assertion that discovering life beyond our planet is “only a matter of time” was made in September 2023. Meanwhile, a headline from September 2024 declared, “We are near.”
It’s easy to understand the reasoning for this perspective. Headlines that state “We’re probably not close” or “No one knows” lack appeal. But what is the general consensus among the relevant expert community? Are optimistic forecasts prevalent or uncommon? Is there even a shared viewpoint? Our recent publication, featured in Nature Astronomy, sheds light on these questions.
From February to June 2024, we conducted four surveys on the probable presence of basic, complex, and intelligent extraterrestrial life. Our inquiries were directed towards astrobiologists (scientists focused on extraterrestrial life) as well as specialists from other fields, including biologists and physicists.
In total, there were 521 responses from astrobiologists, alongside 534 insights from non-astrobiologists. The findings indicated that 86.6% of the participating astrobiologists either “agree” or “strongly agree” that it’s probable some form of extraterrestrial life exists somewhere in the cosmos.
Less than 2% expressed disagreement, with 12% opting for a neutral response. Therefore, it may be concluded that there is a strong consensus regarding the existence of some form of extraterrestrial life in the universe.
Non-astrobiologist scientists showed similar inclinations, with an overall agreement score of 88.4%. This suggests that astrobiologists do not exhibit a bias favoring the belief in extraterrestrial life when compared to their peers.
When analyzing views on “complex” extraterrestrial life or “intelligent” beings, we found agreement rates of 67.4% and 58.2%, respectively, among astrobiologists and other scientists. This indicates a tendency among researchers to believe in the existence of alien life, even in more sophisticated forms.
The significance of these findings is heightened by the low levels of disagreement across all categories. For instance, only 10.2% of astrobiologists opposed the assertion that intelligent aliens are likely to exist.
Optimists and pessimists
Are scientists simply engaging in speculation? Normally, we should only heed a scientific consensus that is founded on evidence (and substantial evidence at that). In the absence of concrete proof, scientists may inherently be guessing. Nonetheless, they had the option to select “neutral,” which some scientists did, expressing their hesitance to speculate.
This option was chosen by only 12%. There actually exists a considerable amount of “indirect” and “theoretical” evidence supporting the existence of alien life. For instance, it is now established that habitable environments are abundant throughout the cosmos.
Within our own solar system, several such environments can be identified, including the subsurface oceans of the moons Europa and Enceladus, and possibly the conditions found a few kilometers below the Martian surface. Moreover, it is pertinent to mention that Mars was once highly hospitable, featuring lakes and rivers of liquid water along with a significant atmosphere.
It is justifiable to extrapolate from this data to an immense number of potentially habitable environments within the galaxy and beyond. Additionally, we can confirm (since our existence is evidence) that life can emerge from non-life – as evidenced by Earth’s own history. Although the origins of the first, primitive life forms remain inadequately understood, there is no persuasive rationale to assume that they necessitate exceedingly rare conditions. Even in such cases, the chances of life originating through abiogenesis are clearly non-negligible.
As the geophysicist Edward Bullard noted back in 1975 during discussions on whether all continents were ever connected, rather than making a definitive choice “it is wiser to remain silent, … take a neutral stance, and await in statesmanlike vagueness for further information.” Not only does remaining silent serve as a secure option for scientists, it indicates that the scientist can avoid deep contemplation – it is the simple choice.
Achieving the right equilibrium
What we likely desire is equilibrium. On one end, we have the absence of direct empirical proof and the hesitance of conscientious scientists to conjecture. Conversely, we have evidence of various forms, including the truly immense number of habitable conditions in the cosmos.
We recognize that the likelihood of life emerging is non-zero. Perhaps an 86.6% consensus, with 12% neutral and under 2% dissent, is a reasonable compromise, when all aspects are taken into account.
Perhaps – given the issue of satisficing – each time we present such findings, we should disclose two figures for overall consensus: one including neutral votes (86.6%), and another excluding neutral votes (97.8%). Neither outcome is the definitive, accurate figure.
Each viewpoint addresses distinct analytical requirements and aids in preventing the oversimplification of the data. In the end, reporting both values – and being open about their contexts – is the most truthful method to depict the genuine complexity of responses.