At least 15 million American adults say they have had a near-death experience, according to a 1997 survey -- and the number is thought to be rising with increasingly sophisticated resuscitation techniques. In addition to floating above their bodies, people often describe moving down a dark tunnel toward a bright light, feeling intense peace and joy, reviewing life events and seeing long-deceased relatives-only to be told that it's not time yet and land abruptly back in an ailing body. There are always skeptics, but there are millions of 'experiencers' who know what happened to them, and they don't care what anybody else says," says Diane Corcoran, president of the International Association for Near-Death Studies, a nonprofit group in Durham, N.C. The organization publishes the Journal of Near-Death Studies and maintains support groups in 47 states. In his new book, Evidence of the Afterlife, Jeffrey Long, a radiation oncologist in Louisiana, analyzes 613 cases reported on the website of his Near Death Research Foundation and concludes there is only one plausible explanation: "that people have survived death and traveled to another [mode of existence]." "The self, the soul, the psyche - throughout history, we've never managed to figure out what it is and how it relates to the body," [said Sam Parnia, a critical-care physician]. "This is a very important for science and fascinating for humankind."