Is there life after death? Radiation oncologist Dr. Jeffrey Long says if you look at the scientific evidence, the answer is unequivocally yes. He makes the case for that controversial conclusion in a new book, Evidence of the Afterlife. He talked to TIME about the nature of near-death experience. [TIME:] How do you respond to skeptics who say there must be some biological or physiological basis for that kind of experience, which you say in the book is medically inexplicable? [Dr. Long:] There have been over 20 alternative, skeptical "explanations" for near-death experience. The reason is very clear: no one or several skeptical explanations make sense, even to the skeptics themselves. Or [else] there wouldn't be so many. [TIME:] You say this research has affected you a lot on a personal level. How? [Dr. Long:] I'm a physician who fights cancer. My absolute understanding that there is an afterlife for all of us - and a wonderful afterlife - helps me face cancer, this terribly frightening and threatening disease, with more courage than I've ever faced it with before. I can be a better physician for my patients.