This thought experiment and its conclusions were described by its authors, Adam Frank and Gavin Schmidt, in an article published in the International Journal of Astrobiology.
What does the Silurian hypothesis say?
The hypothesis is born from a question. How do we really know that there were no earlier civilizations on our planet that rose and fell long before humans appeared? Researchers Adam Frank of the University of Rochester and Gavin Schmidt of NASA’s Goddard Institute for Space Studies started their thought experiment on this question.
“We haven’t seen any evidence of another industrial civilization,” says Frank. “But looking at the deep past in the right way brings up a whole new set of questions about civilizations and the planet: What geological footprints do civilizations leave behind? Is it possible to detect an industrial civilization in the geological record once it disappears from the face of its host planet? “These questions make us think about the future and the past in a very different way, including how any civilization on a planetary scale could rise and fall.”
geological signatures
We could speculate that it is possible that civilizations – before humanity – have completely died out and that their relics have been buried under our feet for hundreds of years. Would it be possible to find “geological fingerprints” of a past civilization that expired millions of years ago?
The researchers considered defining a civilization by its use of energy. Humans began burning fossil fuels more than 300 years ago, ushering in industrialization, for example. It is a way of leaving a geological footprint on the planet. So would global warming, through the release of carbon dioxide and disturbances of the nitrogen cycle from fertilizers; agriculture, through greatly increased rates of erosion and sedimentation; plastics, synthetic pollutants that will be geochemically detectable for millions or a nuclear war, if it occurs, that would leave behind unusual radioactive isotopes.
Both scientists are quick to explain that they don’t actually believe the hypothesis. There is not the slightest evidence of it. But, as they say, “you can’t know until you look, and you can’t look until you know what to look for”.
The Silurian hypothesis in fiction
As a curiosity, it is no coincidence that in the long-running science fiction series “Doctor Who” appears an alien species called the Silurians : technologically advanced humanoid reptiles that lived long before humans, hiding and being basically unknown until our time-traveling alien favorite appeared in his phone booth. This pre- human civilization would have been awakened by nuclear tests after 400 million years of hibernation (Doctor Who refers to them as Homo reptilia).
If the universe is so vast, with so many habitable planets, why haven’t we found any signs of intelligent life? This question leads us directly to the Italian physicist Enrico Fermi and the Fermi paradox, which we have discussed at length before.
Since the publication of the Silurian hypothesis, the authors have unsurprisingly attracted eccentrics and scholars alike . In the same way, as with the Fermi paradox, the hypothesis is also related to the famous Drake equation, used to calculate the number of active civilizations in the Milky Way galaxy.
As well as being an interesting hypothesis to ponder, trying to answer the question could also help us look for signs of advanced civilizations on exoplanets. It is plausible to think that the longer human civilization lasts, the greater the mark one would expect in the geological record, but if that civilization lasts long enough, it goes without saying that its practices will be very sustainable, and thus the smaller the mark on the earth. rest of the planet.
“If a civilization can find a more sustainable way to produce energy without damaging its host planet, it will leave less evidence that it was there. You want to have a good, large-scale civilization that does wonderful things but doesn’t push the planet into realms that are dangerous to itself, the civilization. We need to find a way to produce and use energy that doesn’t put us at risk,” Frank concludes.
Referencia: Gavin A. Schmidt & Adam Frank. The Silurian Hypothesis: Would it be possible to detect an industrial civilization in the geological record? International Journal of Astrobiology, published online April 16, 2018; doi: 10.1017/S1473550418000095
