Does heaven exist? Where do we go when we die? Most of us have asked ourselves these questions at some point. But without any credible evidence of an afterlife, most of us are left to ponder this question until death. Dr. Eben Alexander III, an academic and research neurosurgeon, claims an afterlife does exist. Following a near-death experience, he says there is a heaven, and that he has been there. Alexander is the author of the New York Times best-selling paperback, "Proof of Heaven: A Neurosurgeon's Journey Into The Afterlife."