In theory, the Milky Way could be a 'galactic transport system'
Based on the latest evidence and theories our galaxy could be a huge wormhole (or space-time tunnel, have you seen "Interstellar?") and, if that were true, it would be "stable and navigable". This is the ...
The Wild West of physics
Call it macro-micro physics: the study of the huge paired with the study of the very, very small.