Stephen Hawking, Britain's most eminent scientist, says a belief in a heaven or an afterlife is a "fairy story" for people afraid of death.
In a rejection of religious comforts, Hawking said there is nothing beyond the moment when the brain dies.
Hawking has suffered since the age of 21 from motor neuron disease, an incurable illness that was expected to kill Hawking within a few years of its symptoms arising.
"I have lived with the prospect of an early death for the last 49 years," Hawking told The Guardian. "I'm not afraid of death, but I'm in no hurry to die. I have so much I want to do first.
"I regard the brain as a computer which will stop working when its components fail. There is no heaven or afterlife for broken down computers; that is a fairy story for people afraid of the dark," he said.
Hawking's latest comments follow those laid out in his 2010 book, "The Grand Design," in which he said there is no need for a creator to explain the existence of the universe.
The book provoked outrage from some religious leaders.