- Astrophysicist reevaluated Drake equation using current scientific knowledge and astrobiology literature.
- They concluded that there is substantial probability (up to 85%) that we are alone in the observable universe.
The astonishingly large number of stars in the universe suggests that somewhere in the distant galaxy an intelligent form of life could be warming itself. Yet we haven’t been able to contact them. By all appearances, it seems that humanity is flying solo in the universe.
Hundreds of theories have been proposed to solve this puzzle, one of them is Fermi Paradox, which seeks to answer the question: where are aliens? Or, to put it another way, the universe is enormous, so why can’t we see life outside the Earth?
Recently, three famous scholars at Oxford University’s Future of Humanity Institute reevaluated the paradox in such a manner that it makes it seem like humans are the only advanced civilization in the observable universe.
Optimizing Drake Equation
The team looked at the wide range of probabilities for each parameter of the Drake Equation – an equation for estimating the number of active, extraterrestrial civilization in our galaxy.
To determine the number of civilizations (N), Drake equation multiplies the following parameters:
- Average rate of formations of stars in the Milky Way galaxy (R∗)
- Fraction of stars occupied by planets (fp)
- For stars occupied by planets, the average number of planets that can actually support life (ne)
- Fraction of those planets capable of developing life (fl)
- Fraction of those planets that have developed civilized and intelligent life (fi)
- Fraction of these forms of life that have discovered a way to send detectable signals into space (fc)
- Length of time during which these civilizations transmit detectable signals (L)
Image credit: University of Rochester
This is not the first time authors have tried to solve the Fermi Paradox. In 2013, they extended this paradox to other galaxies as well, by demonstrating that traveling between galaxies is not so difficult for a star-spanning civilization, requiring modest amounts of resources and energy.
In 2017, they proposed that extraterrestrial intelligences aren’t dead, instead, they are in a hibernation state and awaiting suitable conditions in the Universe.
Dissolving the Fermi Paradox
In the latest research, authors reevaluate the parameters of the Drake Equation by introducing genetic and chemical transitions models on paths to origin of life. They showed that there is a significant amount of technical uncertainties, which change multiple orders of magnitude.
Rather than focusing on any specific value equation’s parameters might have, they figured out what the smallest and largest values these parameters could have based on present understanding about the universe.
Reference: arXiv:1806.02404
Over the years, some values have remained far dubious, while some have become well constrained, for example number of planets in the Milky Way and number of habitable exoplanets.
By integrating these uncertainties, instead of vague values that usually go into the Fermi Paradox, the researchers achieved a distribution that tells humanity is probably alone in the universe.
To get to the results, they used present scientific knowledge and astrobiology literature (as a proxy for current technical uncertainties) linked to key parameters. They found no reason to be highly confident that the observable universe consists of other civilizations
Authors never mentioned that the search for extraterrestrial intelligence is hopeless – in fact, opposite. They showed that astrobiology and the search for extraterrestrial intelligence can play a crucial role in decreasing uncertainties of Drake equation parameters.
Read: Is Time Travel Possible? A Hollow Notion or a Distant Possibility?
According to the study, there is great chance that we are alone in the Milky Way galaxy (53% to 99.6%), and perhaps even in the observable universe (39% to 85%).
So, where are the aliens? May be beyond cosmological horizon and forever unreachable.
