In 1901, experiments were carried out in Boston, Massachusetts by Dr Duncan MacDougall and fellow scientists to establish whether or not the “soul” of a human body had mass. MacDougall had theorised that upon the death of an individual, their soul would leave the body, and thus to measure the weight of the person moments before and again moments after their death could ascertain any variances. Using highly sensitive industrial scales, the readings of six terminal patients were recorded. Two of the outcomes were dismissed due to technical issues, but the remaining four extraordinarily revealed a reduction in the weight of the body at the time of death. Dr MacDougall concluded that this change must account for the soul, and calculated its mass to be three-quarters of an ounce or (as it is better known now) twenty-one grams.
The findings of the experiment were published by the New York Times in March, 1907, and immediately became the subject of much scientific scrutiny. MacDougall was criticised for his methods as his equipment and conditions were not satisfactory, his sample size was too small, and he had presented the recordings which best suited his hypothesis rather than providing a full and unbiased paper. Other theories were later proposed to explain the phenomenon, including the fluctuations in body temperature upon death, but the experiment was never replicated, partly due to its ethical and religious implications. Instead, the findings have long since been regarded by professionals as inconclusive at best, and the question as to whether or not the human soul truly does have a mass remains unanswered.