893: 65 Years
In this comic, over 65 years, Randall is projecting the number of living humans who have walked on another world, which seems to include the moon as well. He is using actuarial tables or life tables which shows for each age the probability that a certain person will be alive by their next birthday.
This comic assumes that no one else is going to walk on another world going forward into the future which, as is mentioned in the image text, is a terrible idea for the future of the human race. If the human race only exists on one planet - one disaster can destroy the whole race. However, if humans extend their society to other planets, they lessen the risk of complete extinction.
- [A graph titled 'Number of Living Humans Who Have Walked on Another World' -- its y-axis is numbered 5, 10, 15, it's x-axis increments every ten years from 1960-2040. The line of the graph has a bracket above it that says '65 Years', starting at 1969, ending in 2034.
- The line starts at 1969 and increases steeply to 12 by 1972. It then plateaus until the early nineties declines gradually to 8 between 1991-1999, and then plateaus again.
- From 2020-2035, which is labeled 'Projected Actuarial Tables', the line branches into three and begins to decline more steeply to zero. The area between the first and second branch is shaded and labeled '5th percentile' and the area between the second and third branch is shaded and labeled '95th percentile.']