Is the following logic correct? When spacetime is flat, we say that light travels in a straight line. A planet also would travel in a straight line because that would take the shortest travel time between two points. Does light seek out the shortest time to travel between two points, or the shortest distance? Which one is more fundamental? Now if spacetime is curved, would I say light travels on the curved path because that curved path represents the shortest time it takes light to travel between two points, but not necessarily the shortest distance? And same thing with a planet orbiting a star. Is this logic correct? --> the orbit of the planet represents the shortest time a planet can go from one coordinate to another.