I saw recently from twitter that the mass of a soul was once claimed to be 21 grams. This claim was made by a Dr. Duncan MacDougall in 1907 but the measurements he undertook were not very rigorous and so have no validity at all.
Still I thought it would be fun to work out just how much mass this would amount to, considering the amount lost by all people who had ever lived if it had have been true.
I’m lazy so I looked online and found a reference to Keyfitz’s calculation.(http://www.math.hawaii.edu/~ramsey/People.html) So let’s assume the figure 96,100,000,000 people have lived on the earth. That’s 2.02 x 10^9 grams or 2.02 x 10^6 Kg. To give this some perspective, assuming an adult bull elephant is 5000Kg thats about 400 bull elephants worth of souls.
So that’s a lot of bull.