'It was a place of butterflies, joy and big puffy pink clouds': The leading brain surgeon who is CONVINCED of heaven after 7-day out-of-body odyssey

• Harvard-educated Eben Alexander did not believe patients tales of out-of body experiences
• But now says he experienced a place filled with butterflies while in a coma
• Describes 'a sound like a glorious chant came down from above'
• Says he was accompanied by a young woman