How long do the traces of a civilization last? A thousand years? A hundred thousand? A million? And if they vanish completely—does that mean the civilization never existed?

We assume we would know if advanced societies had preceded us on Earth. We assume the geological record would preserve their footprint. We assume that silence from the deep past means emptiness. But these assumptions have never been tested with mathematical rigor—until now.

Searching for Lost Civilizations takes listeners on a journey from the ruins of Troy and the startling temples of Göbekli Tepe to the submerged coastlines of the last Ice Age, the AI-scanned jungles of the Amazon, and the silent lava tubes of the Moon. Drawing on a groundbreaking quantitative framework developed in the peer-reviewed article “Searching for Lost Civilizations: A Quantitative Framework” (Kriger, 2026), this book introduces the concept of the epistemic horizon—a calculable boundary in time beyond which our current observations carry no information whatsoever about whether civilizations existed.

The answer is not what you might expect. We can confidently rule out civilizations comparable to ours within the last fifty thousand years. But beyond a few hundred thousand years, we are epistemically blind—not because such civilizations didn’t exist, but because we lack the tools to see that far back. And on the Moon, where nothing erodes and nothing subducts, artifacts could survive for the remaining lifetime of the solar system.