I think that this really is just a matter of being vauge. You CAN say hey! that train has a good billionth of an inch befor collision! but the only way to get anywhere like this is to realize that theoreticaly you can fit an infinit amount in a finite space. For example, the Merlov(I think it was him) set. IT starts with a regular triangle(equelateral) and in the middle of each side you place another triangle 1/3 of the size. Then halfway on the new triangles you make one thats 1/3 of the second one ad infinity. But it will never cross the paremeter of a circle drawn around the origenal triangle. Also you can measure a coastline forever by taking smaller and more precise measurements each time. This also goes for time(in my opinion), If you told a friend to tell you when it was exactly 3 pm you would be in the same fix.