earliest members included noted scientists like William Crookes, and philosophers such as Henry Sidgwick and William James. Parapsychological investigation of the afterlife includes the study of haunting, apparitions of the deceased, instrumental trans-communication, electronic voice phenomena, and mediumship. A study conducted in 1901 by physician Duncan MacDougall sought to measure the weight lost by a human when the soul "departed the body" upon death. MacDougall weighed dying patients in an attempt to prove that the soul was material, tangible and thus measurable. Although MacDougall's results varied considerably from "21 grams", for some people this figure has become synonymous with the measure of a soul's mass. The title of the 2003 movie 21 Grams is a reference to MacDougall's findings. His results have never been reproduced, and are generally regarded either as meaningless or considered to have had little if any scientific merit. Frank Tipler has argued that physics can explain immortality, although such arguments are not falsifiable and, in Karl Popper's views, they do not qualify as science. After 25 years of parapsychological research Susan Blackmore came to the conclusion that, according to her experiences, there is not enough empirical evidence for many of these cases. Mediumship Mediums purportedly act as a vessel for communications from spirits in other realms. Mediumship is not specific to one culture or religion; it can be identified in several belief systems, most notably Spiritualism. While the practice gained popularity in Europe and North America in the 19th century, evidence of mediumship dates back thousands of years in Asia. Mediums who claim to have contact with deceased people include Tyler Henry and Pascal Voggenhuber. Near death research Research also includes the study of the near death experience. Scientists who have worked in this area include Elisabeth Kübler-Ross, Raymond Moody, Sam Parnia, Michael Sabom, Bruce Greyson, Peter Fenwick, Jeffrey Long, Susan Blackmore, Charles Tart, William James, Ian Stevenson, Michael Persinger, Pim van Lommel, Penny Sartori, Walter van Laack among others. Past Life Regression Past life regression is a method that uses hypnosis to recover what practitioners believe are memories of past lives or incarnations. The technique used during past-life regression involves the subject answering a series of questions while hypnotized to reveal identity and events of alleged past lives, a method similar to that used in recovered memory therapy and one that, similarly, often misrepresents memory as a faithful recording of previous events rather than a