More than 100 years ago, an American doctor conducted a peculiar study: he attempted to weigh the human soul.
The Enduring Concept of the Soul
An eternal soul is a powerful concept. Many religions center around it, and many people find profound comfort in the belief in a soul when facing loss. Perhaps that’s why some are not content to merely associate the soul with faith, but seek scientific explanations to prove its actual existence. If you’ve ever heard that the soul weighs 21 grams, it’s not just a cinematic or literary trope; it’s the result of one of history’s most unusual experiments.
So, how much does the soul
Dr. Duncan MacDougall’s Peculiar Experiment
This unique experiment was conducted on six terminally ill patients. These patients were placed on special Fairbanks industrial scales before their deaths. Dr. MacDougall intended to measure each person’s body mass before and after their passing to determine any change in weight recorded by the highly accurate scale. The selected patients were all in critical condition, comprising five men and one woman, two of whom suffered from tuberculosis.
Alongside four other doctors, Dr. MacDougall carefully measured the patients’ weights before they died. When they took their last breath, an interesting event occurred.
“Suddenly, immediately after death, the scale’s pointer dropped abruptly and showed no sign of returning. The lost mass was about ¾ of an ounce (approximately 21 grams),” Dr. MacDougall wrote.
The experiment was conducted on the next patient and yielded similar results. Dr. MacDougall felt he had discovered something extraordinary. A news report in The New York Times on March 11, 1907, recorded the historical moment: “As life ceased, the scale’s pointer suddenly dropped, and the result was astonishing; something seemed to have just detached from the body. Immediate calculations were made for normal post-mortem weight loss, but we were still missing 1 ounce.”
All five doctors conducted measurements and compared their results. Not every patient lost the same amount of body mass, but a decrease in mass did occur. Unfortunately, only four patients’ results could be measured due to technical errors; two patients passed away before the doctors could set up the equipment.
So, what caused the weight loss? The doctors calculated all possible losses, such as air in the lungs or bodily fluids, but still couldn’t explain the missing 1 ounce. In the third patient, an interesting variation occurred: the body mass didn’t change immediately after death, but one minute later, the body’s weight dropped by 1 ounce. Dr. MacDougall explained this difference as follows:
“I believe that in this case, the man’s soul lingered in his body for a minute after death before it was set free. There’s no way to calculate it; I assume the difference is due to the individual’s differing temperament.”
After testing and consulting with the other participating doctors, it was determined that the average weight loss for each person was ¾ of an ounce. Dr. MacDougall concluded that the human soul weighs 21 grams.
Experiments on Animals and Later Developments
Dr. MacDougall conducted similar experiments on 15 dogs. The experiments showed no change in weight after their deaths. MacDougall concluded that this might indicate that only humans possess a soul.
H.LAV.Twining, a physics teacher at Los Angeles Polytechnic High School, attempted a similar experiment on mice in 1917. His conclusion was consistent with Dr. MacDougall’s: there was no weight deviation when the mice died.
Dr. MacDougall was a respected physician from Haverhill and the head of the Society for Psychical Research in his field for six years before the official experiment. Although this experiment is considered unethical in modern times, it remains a unique study that has attracted much criticism from various religious perspectives.
Dr. MacDougall admitted that more research was needed to verify the results, but after these experiments, he shifted his research to the possibility of capturing images of the soul through a camera as a person died. Unfortunately, Dr. MacDougall’s career did not achieve any further memorable accomplishments after his experiment on the weight of the soul. Dr. Duncan MacDougall passed away in 1920.
Unanswered Questions
Dr. MacDougall’s study had a very small sample size, so even at the time, many people were skeptical of his findings. He himself acknowledged that more experiments were needed to confirm that the soul has mass. But no one conducted further experiments, partly for ethical reasons and partly because these experiments were considered somewhat bizarre.
In the early 2000s, an Oregon farmer in the US attempted to replicate the soul-weighing experiments with 12 sheep and found that most of their mass increased by 30 to 200 grams, but after only a few seconds, their mass returned to normal. This event was documented in Mary Roach’s 2005 book, Spook: Science Tackles the Afterlife.
The author also noted that Dr. Gerry Nahum, a chemical engineer and physician at Duke University at the time, developed a hypothesis that the soul, or at least consciousness, must be linked to information, meaning it corresponds to a certain amount of energy. Since the equation E=mc2 (Einstein’s formula) dictates that energy equals mass multiplied by the speed of light squared, this energy could, in principle, be weighed with sufficiently sensitive electromagnetic instruments. As of 2007, Dr. Nahum had not received funding for experiments to prove or disprove his assertion.
In short, science has not determined the weight of the soul, nor whether the soul exists, and the explanation remains within the realm of religious faith.
