Suppose you are in a vessel traveling at relativistic or near relativistic speed relative to your local galaxy--whatever is physically reasonable, and won't get rapidly torn apart by high energy collisions.
A couple of things should probably happen, right:
- The background glow and light of the galaxy should blueshift in the direction you are travelling.
- Any hydrogen, dust, or small particles that you hit will have large energies
With that in mind, what would the apparent exterior "temperature" be in front of the ship, the nature of the "frictional" force involved (given the vessel is about building sized), and how much force would be involved; further, would this be a force as we think of it at non-relativistic speeds, or a degrading wind that has an acid-like vaporizing impact on the matter of the ship due to the properties of high energy particle collisions?
On the brighter side, is there some lower speed where there exists a balance between the incident energy and the material integrity of the ship such that the people on board could actually have access to an energy source: e.g. the "frictional heat" (particle collisions) or increase in the frequency component of the energy of incident photons that they experience on the leading surfaces of their vessel?