Death is inevitable.

It is the single unerring truth in this world and a journey which we all must take. But, what is it exactly and when does it occur? When are we here, and when are we not?

The answer is not as simple as you think.

Far from being just one single event, it appears to be more of a slow, drawn-out process in which some cells continue to survive even after death.

But how, and why is this the case?

Dr Peter Noble of the University of Washington in Seattle joins Jonathan to discuss how we define death, not just in medical terms, but as a society.