Probably the MOST difficult factor to estimate in the Drake equation is:

Question

Quizplus · Accepted Answer

While all factors in the Drake equation are difficult to estimate with certainty, the lifetime of a technologically advanced civilization (L) is particularly challenging because it requires us to make assumptions about the longevity of technological progress, the sustainability of a civilization, and the potential for catastrophic events that could destroy a civilization (e.g. nuclear war, environmental collapse, etc.). Thus, many scientists consider L to be the most uncertain and speculative factor in the equation.

Probably the MOST Difficult Factor to Estimate in the Drake