The silurian hypothesis is not a theory, but rather a thought experiment: what if a civilization had existed on Earth millions of years ago? After such a long time, could it have left any trace, taking into account the natural decay of all materials, sedimentation and plate tectonics? This video is not about an actual ancient civilization of which we have zero evidence. It is about how long the remains of a technically advanced civilization such as ours could last, and testify of our existence. This means looking into things such as the durabily of the materials we use and the things we build, the time it takes for our waste to disappear, geology, erosion... And also what kind of physical evidence of their existence different civilizations may leave behind them.