The Silurian hypothesis is a thought experiment which assesses modern science's ability to detect evidence of a prior advanced civilization, perhaps several million years ago. The most probable cues for such a civilization could be carbon, radioactive elements or temperature variation. The name "Silurian" derives from the eponymous sentient species from the BBC science fiction series Doctor Who, who in the series established an advanced civilization prior to humanity.
Astrophysicists Adam Frank and Gavin Schmidt proposed the "Silurian Hypothesis" in a 2018 paper, exploring the possibility of detecting an advanced civilization before humans in the geological record. They argued that there has been sufficient fossil carbon to fuel an industrial civilization since the Carboniferous era (~350 million years ago). However, finding direct evidence, such as technological artifacts, is unlikely due to the rarity of fossilization and Earth's exposed surface. Instead, researchers might find indirect evidence, such as climate changes, anomalies in sediment, or traces of nuclear waste. The hypothesis also speculates that artifacts from past civilizations could be found on the Moon and Mars, where erosion and tectonic activity are less likely to erase evidence. The concept of pre-human civilizations has been explored in popular culture, including novels, television shows, and short stories.
According to Frank and Schmidt, since fossilization is relatively rare and little of Earth's exposed surface is from before the Quaternary time period (~2.5 million years ago), there is low probability of finding direct evidence of such a civilization, such as technological artifacts. After a great time span, the researchers concluded, contemporary humans would be more likely to find indirect evidence such as rapid changes in temperature or climate (as occurred during the Paleocene–Eocene Thermal Maximum ~55 million years ago); evidence of tapping geothermal power sources; or anomalies in sediment such as their chemical composition (e.g., evidence of artificial fertilizers) or isotope ratios (e.g., there is no naturally occurring plutonium-244 outside a supernova, so evidence of this isotope could indicate a technologically advanced civilization). Objects that could indicate possible evidence of past civilizations include plastics and nuclear wastes residues buried deep underground or on the ocean floor.
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Astrophysicists Adam Frank and Gavin Schmidt proposed the "Silurian Hypothesis" in a 2018 paper, exploring the possibility of detecting an advanced civilization before humans in the geological record. They argued that there has been sufficient fossil carbon to fuel an industrial civilization since the Carboniferous era (~350 million years ago). However, finding direct evidence, such as technological artifacts, is unlikely due to the rarity of fossilization and Earth's exposed surface. Instead, researchers might find indirect evidence, such as climate changes, anomalies in sediment, or traces of nuclear waste. The hypothesis also speculates that artifacts from past civilizations could be found on the Moon and Mars, where erosion and tectonic activity are less likely to erase evidence. The concept of pre-human civilizations has been explored in popular culture, including novels, television shows, and short stories.
According to Frank and Schmidt, since fossilization is relatively rare and little of Earth's exposed surface is from before the Quaternary time period (~2.5 million years ago), there is low probability of finding direct evidence of such a civilization, such as technological artifacts. After a great time span, the researchers concluded, contemporary humans would be more likely to find indirect evidence such as rapid changes in temperature or climate (as occurred during the Paleocene–Eocene Thermal Maximum ~55 million years ago); evidence of tapping geothermal power sources; or anomalies in sediment such as their chemical composition (e.g., evidence of artificial fertilizers) or isotope ratios (e.g., there is no naturally occurring plutonium-244 outside a supernova, so evidence of this isotope could indicate a technologically advanced civilization). Objects that could indicate possible evidence of past civilizations include plastics and nuclear wastes residues buried deep underground or on the ocean floor.
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