There are two ways things handle time. First, there is aging and perishability: things die because they have a biological clock, what we call senescence. Second, there is hazard, the rate of accidents. What we witness in physical life is the combination of the two: when you are old and fragile, you don’t handle accidents very well. These accidents don’t have to be external, like falling from a ladder or being attacked by a bear; they can also be internal, from random malfunctioning of your organs or circulation.

