A 2018 paper by Gavin Schmidt of the NASA Goddard Institute for Space Studies and Adam Frank of the University of Rochester, published in the International Journal of Astrobiology, asking what geological trace an industrial civilisation would leave after tens of millions of years. Its working answer is that direct artefacts would be essentially undetectable, that the readable signal would be isotopic and sedimentary, resembling the hyperthermal events already present in the record, and that our own era will be legible mainly as a thin chemical layer. The paper is often cited in the alternative literature as licence for a lost technological civilisation, which inverts what it says: the authors state plainly that they doubt any previous industrial civilisation existed before our own, and offer the exercise as a way of calibrating what a biosignature search could and could not find on another planet. It is a useful entry precisely because it is a peer-reviewed treatment of a fringe premise that arrives at a sceptical conclusion, and because the gap between the paper and its citations is easy to check.
Connections
Lost Civilization Hypothesis · Ancient Astronaut Hypothesis · Younger Dryas Impact Hypothesis · Galileo Project · Project Hail Mary · Simulation Argument · Nick Bostrom