Should we send messages into space in an effort to contact intelligent extra-terrestrial civilizations? Or should be fear them attacking us and transmit nothing? Two conflicting and oft-heard questions, but it turns out we may overlooking something rather important and completely obvious— it’s probably us that are the malicious aliens.
When I read that we’ve got more chance of being struck by a planet-killer asteroid than being invaded by aliens, I was intrigued.
So I got in touch with Alberto Caballero, the author of the though experiment-style paper published this week, to find out more. His paper is an attempt to determine how many malicious extraterrestrial civilizations there could be, and how likely it is that they would invade us.
The figure he comes up with is staggeringly small. By extrapolating data on the world’s history of invasions in the last century, the military capabilities of the countries involved, and the global growth rate of energy consumption, there’s a 0.0014% chance of Earth being invaded by a technologically advanced civilization.
That figure is largely based on the fact that the more advanced a civilization the less likely it is to revert to attack. for “more advanced” read “consumes more energy.” That, after all is the driving forces behind the classical division of space-faring civilizations known as the Kardashev Scale:
- Type 1 or “planetary” civilization: has harnessed all major forms of energy available from its home planet and also includes the energy received by the home world from its parent star.
- Type 2 or “stellar” civilization: can obtain and store all the energy its parent star releases, probably through things like Dyson spheres. Power consumption is ten orders of magnitude more than a Type 1 civilization.
- Type 3 or “galactic” civilization: can access and control much of the energy the entire galaxy generates.
Wait. Why would technologically advanced Type 1/Type 2 civilizations that consume more energy be less likely to invade? “Data from last century shows that the frequency of invasions between countries have gradually decreased as time goes by,” said Caballero in an email this week. “Based on that data a civilization like humanity would be more likely to invade than a Type-1 civilization, but they would not have the means to travel to an extraterrestrial planet.”
There will be no aliens attacking each other, at least for now. So why the fear about attempts to make contact (known as messaging extraterrestrial intelligence or METI)? “For the general public, the fear probably comes from all the decades of Hollywood movies about alien invasions,” said Caballero. Only in a very few movies – such as 2016’s Arrival – are extraterrestrial invaders peaceful.
“For the scientific community it’s is considered as something that does not guarantee benefit and, therefore, it is not worth the shot,” said Caballero, who thinks a similar thing happens with the search for extraterrestrial intelligence (SETI), which does not have any public financial support.
Caballero also thinks there haven’t been any studies that estimate the prevalence of malicious civilizations or the probability of extraterrestrial invasion, hence his own effort. “It has not been possible to contrast the potential benefits versus the risks of sending a serious message,” he said.
In other words … calm down, look up, and think about something you might want to say to another intelligent civilization thousands of light-years distant. After all, according to Caballero’s calculations we’ve got 18,000 radio signals to send potentially habitable planets before the probability of one of them being malicious is as the same as the probability of Earth colliding with a massive asteroid that would kill a quarter of all humans.
Wishing you clear skies and wide eyes.