A new study has proposed the latest in a long line of bleak solutions to why we haven’t yet found signs of intelligent life out there in the universe.
The universe is a big place. With 200 billion trillion (ish) stars in the universe and 13.7 billion years that have elapsed since it all began, you might be wondering where all the alien civilizations are at. This is the basic question behind the Fermi paradox, the tension between our suspicions of the potential for life in the universe (given planets found in habitable zones, etc) and the fact that we have only found one planet with an intelligent (ish) species inhabiting it.
All sorts of solutions have been proposed for the Fermi Paradox, from the simple – life could be rare, and the differences in time and space too far to communicate – to aliens keeping us isolated in a sort of galactic zoo. Several claim that aliens simply wipe out other species rather than compete with them for resources and so everybody else tries to stay quiet, while other, equally bleak scenarios suggest that aliens don’t need much help wiping themselves out, thank you very much.
The new paper is in the latter camp, suggesting that alien civilizations meet their ends long before they have a chance to get chatty with fellow intelligent life. According to the preprint paper, which has yet to be peer-reviewed, intelligent civilizations likely meet their end due to climate change on whatever planet they inhabit, on astronomically very short timetables.
In this universe we obey the laws of thermodynamics. Everything moves towards disorder, and no matter how efficient we try to make power generation, we will always produce waste heat. Technological civilizations will likely always encounter the problems humanity faces at the moment; a planet that is increasingly uninhabitable to it, and whatever creatures it shares the planet with.
“Our analysis suggests that, if the energy growth rate is of order 1 percent per year, the maximal lifetime of such putative technospheres is ephemeral compared to stellar evolution,” the team writes in their paper. “The upper bound on the lifetime of technospheres is relatively insensitive to stellar spectral type, and is merely hundreds of years in duration.”
If civilizations last just a thousand years at most, and are relatively rare, detecting their presence would be unlikely, and would offer a partial solution to the Fermi Paradox. According to the team, “we have not encountered technological species because they are rare at any given moment in time”.
This isn’t to say that we couldn’t pick up signals from such civilizations, but it might mean that by the time we receive them they are likely dead, or long dead. Detecting alien life, they suggest, may come from seeing the lasting damage a civilization did to their planet before they promptly destroyed themselves.
Before you add “alien ghosts” to your lists of things to worry about, the authors do suggest other possible trajectories for advanced civilizations. The team briefly considers options available to advanced and ever-expanding civilizations to combat this excess heat generation, such as altering the atmosphere with aerosols, altering their star, or nudging their planet into a preferable orbit. However, they suggest that civilizations can drastically increase their longevity by learning to live within their means, and reducing their energy consumption.
“If a species has opted for equilibrium, has learned to live in harmony with its surroundings, that species and its descendants could survive maybe up to a billion years,” astrophysicist Manasvi Lingam, and co-author of the study, told Live Science.
Maybe we should try that, instead of becoming a space ghost for some similarly doomed intelligent alien species to detect.
The study is posted to preprint server arXiv.
Source Link: We May Only Ever Detect Signals From Long-Dead Alien Civilizations
