Length of time such civilizations release detectable signals into space, L, pre-1961
This chapter is an overview of the prehistory of L, how people across the globe from our earliest sources to 1961 have tried to understand the beginning and end of history, and the rise and fall of civilizations. Factor L is put into a longer historical context of human conceptions about history, time, and civilization. In focus is the question of how it was possible to formulate L in its modern v
