Given that our galaxy has a volume of approximately 8 × 10¹² ly³, what would be the average minimum amount of time to exchange messages between civilizations if there are currently 125,000 intelligent civilizations in our galaxy? A) 800 years B) 1,200 years C) 200 years D) 400 years

Question

Quizplus · Accepted Answer

The average distance between civilizations is (8 × 10^12 ly^3 / 125,000)^(1/3) = 4 × 10^4 ly. At the speed of light, it would take 4 × 10^4 ly / (3 × 10^8 km/s) / (3.15 × 10^7 s/yr) = 400 years to send a message.

Given That Our Galaxy Has a Volume of Approximately 8