A recent study by astronomers Kipping and Lewis suggests that the existence of intelligent life in our galaxy may be an all-or-nothing proposition, with the galaxy either teeming with life or completely devoid of it. This unsettling conclusion has significant implications for the search for extraterrestrial intelligence (SETI) and our understanding of our place in the universe.
The Fine-Tuning Problem and The Jaynes Experiment
In 2013, the scientists Tom Westby and Christopher J. Conselice were commissioned to calculate exactly how many slots are left in our Milky Way Galaxy for intelligent beings who have not yet been found anywhere on Earth. The reasoning goes that in the Jaynes’ Experiment, such life will be born from a probability distribution which is either heavily biased towards abounding or scant with rarity, and that you ought not find it filling the middle of the spectrum.
For those of you who have a hunch (rather than evidence) that intelligent life is fairly widespread in the Milky Way, this leaves a challenge to SETI Optimists. The authors claim that this would only be true of the circumstances for life to evolve were fine-tuned in a similar fashion as are the fundamental constants governing our universe, which must support matter and large-scale structures. If we assume the fine-tuning problem for life itself, one can imagine probability that may be either incredibly unlikely or unjustifiable high — virtually no middle ground.
Birth-Death Model of Civilizations
To solve the puzzle, Kipping and Lewis reimagined the Drake Equation —an attempt to estimate that number of extra-terrestrial civilizations (ETCs) in our galaxy. Their framework deserves careful attention, however because of its simplicity relative to the Drake Equation which has many input parameters.
This simplification then yielded the S-shaped distribution of probabilities for ETCs to exist in Milky Way. This implies life in the galaxy could be very common or extremely rare but with little middle ground. The authors argue that this conclusion is unavoidably plausible, stemming from basic principles of population growth and ecology.
Conclusion
Kipping and Lewis paint a truly dire picture. If they are right scientists may have an uphill battle in simply trying to locate any extraterrestrial intelligence with the odds against doing so apparently being quite poor. Although ”The Formula for a Forbidden Signature of Extra-Terrestrial Civilization” discourages false alarm to be raised, the paper stresses that SETI is still relevant and valuable as discovering even an improbable alien civilization would constitute one o\t biggest scientific discovery ever. They also indicate that a search through extra-galactic sources might be worthwhile, as it is possible that the Milky Way galaxy we occupy is an odd place where things are relatively peaceful. As a result, this work becomes yet another startling perspective point in our literature regarding the prevalence of life in the cosmos and it is definitely one that will feed into future discussions on cosmological anthropic principles.
