The "21 Grams" Experiment (1907) In the early 20th century, Dr. Duncan MacDougall attempted to measure the soul using the most modern tech of his time: industrial beam scales.  • The Metric: He placed six terminally ill patients on beds equipped with sensitive scales. He claimed that at the exact moment of death, one patient lost three-fourths of an ounce—roughly 21 grams.  • The Myth: Although his science was flawed (likely just sweat or air leaving the lungs), the number 21g became the global "standard" for the weight of a soul.