US neuroscientist David Eagleman's book Sum, about the fictional possibilities of the afterlife, has been turned into a production at the Royal Opera House.

The bestseller is based on Eagleman's idea that we should be open to the fictional possibilities of what consciousness could be like after death.

David Eagleman talked to the BBC's Tom Bateman about the various theories of what forms consciousness - whether it is a property of the human brain or a "property of the universe".

He said that thinking about the afterlife in new terms leads to thoughts about what it means to be alive, saying that for some people the book was "a call to arms" to look at their actions during their lifetime and how we they do them better.

The director of the play, Wayne McGregor, told the Today programme's Tom Bateman that he found the book "haunting" and explained that it made him think differently about the very meaning of consciousness.

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