The Milky Way has millions of potentially liveable planets, with about four of them harbouring evil alien civilisations that would conquer Earth if they could, states a new study. The study, which hasn’t been peer-reviewed yet, asks an intriguing question — what are the chances that humans may one day come into touch with a hostile alien civilisation capable of invading our planet? Alberto Caballero, the study’s author and a PhD student in conflict resolution at the University of Vigo in Spain, began by looking back at human history before gazing out to the stars in order to find the answer.
For that, Caballero first started counting the number of countries that invaded others nations from 1915 to 2022. During that time, he discovered that 51 of the world’s 195 countries have conducted some type of invasion. Then, he calculated the chance of each country launching an invasion based on its share of global military spending.
Caballero added each country’s individual probability of inciting an invasion by the total number of countries on Earth, arriving at the current human probability of invasion of an extra-terrestrial civilisation.
The study was published in the arXiv preprint database.
Caballero noted that the paper sought to provide an evaluation of the prevalence of hostile extra-terrestrial civilisations “through an extrapolation of the probability that we, as the human civilisation, would attack or invade an inhabited exoplanet.”
The current probability of humans invading another inhabited planet, according to this estimate, is 0.028 percent. That probability, however, applies to the current stage of human civilisation, according to Caballero, since humans aren’t capable of interstellar travel yet.
Using the Kardashev scale — a metric that categorises how evolved society is based on its energy expenditure — he predicted that interplanetary travel won’t be achievable for another 259 years if current rates of technological improvement remain the same.
If the frequency of human invasions continues to decline at the same rate as it has over the last 50 years — an average of minus 1.15 percent per year — the human race will have a 0.0014 percent chance of invading another planet when it becomes an interstellar civilisation 259 years from now.
Caballero based his final figure on a 2012 paper published in the journal Mathematical SETI, in which researchers predicted that up to 15,785 alien civilizations might theoretically co-exist with humans in the cosmos.
The researcher came to the conclusion that just 0.22 of the interstellar civilisations would be hostile to humans if they came into contact with them. When civilisations that are not yet capable of interplanetary travel, such as modern humans, are included, the number of evil neighbours rises to 4.42.
It doesn’t seem like there’s anything to be concerned about with 4.42 hostile alien powers. Caballero said that the chances of humanity contacting one of these hostile civilisations — and subsequently being overrun by them — are vanishingly unlikely.