If I drive one kilometer along a straight road from A to B in a car that is a simple path.
If I was smaller though (say ant-size) I would have to traverse the road following all the contours in the asphalt. From A to B would be a much greater distance for an ant.
If I was even smaller though I would have to begin navigating the space between particles to get from A to B. At this scale would atoms exert gravitational forces on me and would I be able to enter a nucleus or would electrons prevent me from doing so?