It's a question that constantly plagues humanity: are we alone? Scientists now say that, yes, it's likely the galaxy is devoid of other intelligent life.

The Fermi Paradox

Named after Italian physicist Enrico Fermi, the Fermi paradox is basically another question: where are the aliens?

After all, considering all the billions of stars in the universe — a handful are even very similar to the sun — it's likely intelligent life exists in another galaxy system somewhere out there. Like humans, they might have developed advanced technology and interstellar travel. Since a lot of the stars and galaxies in the universe are billions of years older than Earth, the civilizations should have been able to get here by now.

So why haven't we found a sign of extraterrestrial life?

The Answer To The Paradox

In a new study titled "Dissolving the Fermi Paradox" released online, three famous scientists from the Future of Humanity Institute in Oxford University have clapped back at the question, saying that the reason we haven't found intelligent life outside of Earth is because it's likely that they do not exist.

The three scientists who conducted the study are Anders Sandberg, Research Fellow at FHI and Martin Senior Fellow at the university; engineer Eric Drexler, who popularized nanotechnology; and Tod Ord, an acclaimed moral philosopher.

Together, the trio sought to provide a more realistic picture of life outside Earth.

One of the tools that is often used to demonstrate the existence of aliens is the Drake equation, which suggests that even if there's a miniscule probability of intelligent life getting to develop at a specific site, the sheer number of potential sites will still produce a high amount of other potentially observable civilizations.

The equation — expressed mathematically as N = R* x fp x ne x fl x fi x fc x L — assumes certainty on uncertain parameters, assigning single numbers to these unknown variables, the three scientists point out in the recent paper.

The trio worked on the equation by using models of chemical and genetic transitions on the paths to the origin of life, which reveals many uncertain parameters spanning multiple orders of magnitude. They also use uncertainty ranges in the equation, focusing on the smallest and largest values possible given scientific knowledge instead of using a single value.

In an email to Universe Today, Sandberg explains that the Drake equation is based on uncertain parameters and estimates and is also sensitive to personal bias.

The Conclusion

Using their new model, the scientists find that it's likely no other intelligent life exists in the observable universe. Specifically, the figures show that there's a 53 to 99 percent probability that humanity is the only living civilization in the whole galaxy and a 39 to 85 percent probability that humanity is even alone in the observable universe.

"'Where are they?' — probably extremely far away, and quite possibly beyond the cosmological horizon and forever unreachable," the paper concludes.

The new study reveals that it should not be surprising to find the galaxy devoid of intelligent life outside of Earth. However, it stresses most of all how uncertain the scientific knowledge still is on extraterrestrial life.

"There is a tremendous level of uncertainty to reduce," Sandberg explains. "The paper shows that astrobiology and SETI can play a big role in reducing the uncertainty about some of the parameters. Even terrestrial biology may give us important information about the probability of life emerging and the conditions leading to intelligence."