If we imagine that 1 in 10 million stars would eventually give rise to a civilization on an orbiting planet and assuming that there are 100 billion stars in our Milky Way galaxy, how often should a civilization randomly appear over a 5 billion year period?
A) once every 50 million years
B) once every 50,000 years
C) once every 500,000 years
D) once every 5 million years

Question

Quizplus · Accepted Answer

If 1 in 10 million stars gives rise to a civilization, then there are approximately 10,000 civilizations in our galaxy. Over a 5 billion year period, this would result in a potential appearance of a civilization every 500,000 years. Therefore, the best answer is C.

If We Imagine That 1 in 10 Million Stars Would