Are We Too Late? Astronomers Look for Ruins of Ancient Space Civilizations

Over half a century ago, Dr. Frank Drake, a radio astronomer at the National Radio Astronomy Observatory in Green Bank, West Virginia, developed an approach to estimating the number of technologically advanced civilizations that exist in our galaxy.

Back in 1961 he came up with a formula which has become known as Drake Equation, which allows one to calculate the number of extraterrestrial civilizations in the Milky Way galaxy by looking at the probability of specific factors arising which are thought to play a role in the development of such civilizations.

Since then, the Search for Extraterrestrial Intelligence (SETI) has owed a great deal of its observational and theoretical framework to the Drake Equation.

However, SETI has also been strongly influenced by what has become known as Fermi’s Paradox, put forward by Italian physicist Enrico Fermi. It asks why humanity has no observational evidence for other intelligent civilizations, despite there being an apparent abundance of potential habitats for life and intelligence and ample time for civilizations to make their presence felt either via interstellar communication at light speed or exploration via physical probes sent at speeds comparable to those achieved by humanity’s spacecraft.

There have been a number of solutions to Fermi’s Paradox.

Current SETI searches rely on detecting intentional or unintentional signals at a variety of wavelengths. These searches generally set upper limits on the population and broadcast strength of communicating civilizations, but with only one civilization in our sample (humanity), predicting which proposed solution to Fermi’s Paradox holds true is extremely difficult.

British astronomers have recently offered a new solution to the paradox.

What if the extraterrestrial civilizations annihilated themselves long before we actually started attempting to find them?

Adam Stevens, Duncan Forgan and Jack O’Malley James used the Earth as a test case in order to categorize the potential scenarios for complete civilizational destruction, quantify the observable signatures that these scenarios might leave behind, and determine whether these would be observable with the current technology or technology which might be available in the near future.

The results of their research have been published by the Cornell University Library.

“The variety of potential apocalyptic scenarios are essentially only limited in scope by imagination and in plausibility according to our current understanding of science,” they say in the article. “However, the scenarios considered here are limited to those that: are self-inflicted (and therefore imply the development of intelligence and sufficient technology), technologically plausible (even if the technology does not currently exist), (in the test case)  and that totally eliminate the human civilization (in the test case).”

The astronomers therefore analyzed various ways that humanity could destroy its own civilization, and the observational signatures these events may produce.

Those ways include: i) complete nuclear, mutually-assured destruction ii) a biological or chemical agent designed to kill either the human species, all animals, all eukaryotes, or all living things iii) a technological disaster such as the “grey goo” scenario, or iv) excessive pollution of the star, planet or interplanetary environment.

The researchers also discussed the timescales on which these signatures might persist, and prospects for their detection by present and future observations.