Geometry in Space

I wonder if the first sailors expected vast stretches of nothingness when contemplating an ocean crossing - especially the ones who went just to see what might be on the other side. Whenever I contemplate writing the space flight portions of books I find I have to constantly challenge my assumption that traveling through interstellar space would entail vast stretches of nothing but vacuum. Recent photos from a series of new telescopes the world (and orbiting said world) over provide terrific views of the galaxy as a dynamic, living system which sometimes defies explanation. The 'impossible star', a star forming in the constellation of Scorpius, apparently exceeds the theoretical limit for a star's mass. What a thing for characters to see while tooling around interstellar space - phenomena that challenge the known laws of physics.