One man’s obsessive quest to weigh the human soul
Get the Popular Science daily newsletterđź’ˇ Breakthroughs, discoveries, and DIY tips sent six days a week. Can you measure the weight of a human soul? No, but that didn’t stop Duncan MacDougall from trying. In the early 20th century, MacDougall put dying patients on a scale to try and prove the existence of a soul. One of MacDougall’s first test subjects was a tuberculosis patient. He was placed on the bed as he neared death. With doctors watching over, the man died, and MacDougall noticed the scale’s counterweight dropped with surprising quickness. The scales displayed the weight that had been lost upon death: Âľ of an ounce, or 21 grams. Had MacDougall solved a mystery that had plagued philosophers, theologians, and medical professionals for millennia? Not exactly. The “21 Grams Experiment,” as it’s come to be known, is the fascinating topic for our latest Popular Science video. While MacDougall’s experiment was deeply flawed, the idea behind it remains so appealing, more than a century later. We keep coming back to the 21 grams experiment because …









