In 2008, neurosurgeon Dr. Eben Alexander contracted a rare form of bacterial meningitis that shut down parts of his brain, put him in a coma and nearly killed him. During this time, he says, he saw heaven. As he came out of the coma, Dr. Alexander didn't recognize anyone -- even his own son. "The only... really truly terrifying moment of that whole journey and coma was seeing [my son's] face," he says. Oprah's "Super Soul Sunday" interview with Dr. Alexander airs Dec. 2 at 11:00 a.m. ET on OWN.