 You can find a more detailed discussion of the nature of time elsewhere in this encyclopedia (see the separate entry on  time).  The most relevant debate for our purposes turns on whether distant times are like distant places. For example, people, objects and places in Antarctica exist, even though they are far away (if you are reading this in Antarctica, please adjust the example). It can be difficult to communicate with distant places, and they may be less important to us than our immediate surroundings, but they exist nevertheless. What about eighteenth-century people, objects and times? Does David Hume exist, despite being far away in time? Or is it more reasonable to say that Hume used to exist, but now does not exist?  Eternalists believe that past and future things exist, just like present things. Presentists, in contrast, believe that distant times are not like distant places: things in distant places exist, but things at distant times do not. According to the intermediate ‘growing universe’ theory, past and present things exist, but future things do not.