Final answer:
In Physics, objects or entities like trains and magnetic field lines, moving in opposite or divergent directions will never intersect, as they would have to have different directions at the same point, which cannot occur in physical space.
Step-by-step explanation:
The question refers to the concept of motion and directions, which is a key topic in Physics, particularly when discussing trains or any other bodies in motion. In the physical world, two objects moving in the same way will always have the possibility to intersect or cross paths. However, if they move in parallel but opposite directions, or on pathways angled in such a way that they diverge, they will never intersect. Similarly, when discussing magnetic field lines, it's stated that they cannot cross because at the point of intersection, the magnetic field would have two different directions, which is not possible given that the field at any point in space has a single unique direction.