21 Grams: The Weight of The Soul

What is a soul? Can it be touched? Does it have mass? These questions tormented Duncan MacDougall, a physician from Haverhill, Massachusetts, so much that he devised an experiment to determine whether souls have physical weight.  “The soul leaving the body” by Luigi Schiavonetti, circa 1810. MacDougall postulated that the soul was material and therefore, there should be a measurable drop in the weight of a person when the soul departed the body. In 1901, MacDougall selected six terminally ill patients from a nursing home, four suffering from tuberculosis, one from diabetes, and one from unspecified causes. MacDougall specifically chose people who were suffering from conditions that caused physical exhaustion, as he needed the patients to remain still when they died to measure them accurately. MacDougall then rigged a special bed in his office that sat upon an industrial sized platform beam scale sensitive to two-tenths of an ounce, or about 5.6 grams. Upon this bed he placed, in succession, the six patients, and observed them before, during, and after their death, measuring any corresponding changes in weight. MacDougall meticulously recorded his observations: The patient’s comfort was looked after in every way, although he was practically moribund when placed upon the bed. He lost weight slowly at the rate of one ounce per hour due to evaporation of moisture in respiration and evaporation of sweat. During all three hours and forty minutes I kept the beam end slightly above balance near the upper limiting bar in order to make the test more decisive if it should come. At the end of three hours and forty minutes he expired and suddenly coincident with death the beam end dropped with an audible stroke hitting against the lower limiting bar and remaining there with no rebound. The loss was ascertained to be three-fourths of an ounce.