posted on Jun, 4 2023 @ 08:23 AM
Now let's go the other way...
If there were only 2 people in the year 1 AD, and each person died at the age of 40, and each couple had one child at the age of 30, let's calculate
the number of people who would be alive today.
Considering a generation span of 30 years, we can calculate the number of generations that have passed from the year 1 AD to the present day.
2023 years (current year) / 30 years per generation ≈ 67.43 generations
Since we cannot have a fraction of a generation, let's round down to 67 generations. Therefore, it would have taken 67 generations to reach the
present day from the year 1 AD.
Now, let's calculate the number of people alive today. We start with the original couple (2 people) and each subsequent generation doubles in size.
However, since each person dies at the age of 40, we need to account for the decrease in the number of living individuals after that age.
Generation 1: 2 people (the original couple)
Generation 2: 2^1 = 2 people (1 child of the original couple)
Generation 3: 2^2 = 4 people (2 grandchildren of the original couple)
...
To account for the decrease in the number of living individuals after the age of 40, we divide the number of people in each generation by 2. This
assumes that half of the individuals are still alive at any given time until they reach the age of 40.
The number of people alive today can be calculated by summing up the number of people in each generation up to the 67th generation, while taking into
account the decrease in the number of individuals after the age of 40:
(2 + 2^1/2 + 2^2/2 + 2^3/2 + ... + 2^66/2)
Using the formula for the sum of a geometric series, the total number of people alive today would be:
(2^(67+1)/2 - 2) = 2^68/2 - 2 ≈ 5.53767779 × 10^20
Therefore, if there were only 2 people in the year 1 AD, and each person died at the age of 40, and each couple had one child at the age of 30, there
would be approximately 5.53767779 × 10^20 people alive today.