First you could do it with color changes and not have to have UV or IR and still pull it off (semi-)realistically
Why not use the 3D anaglyph system from 0.9.7.2 for color shifting?
I agree that this kind of trick would be quite usefull. But I agree much more with SpaceEngineer when he says:
We could use a set of real textures for some wavelengths, but smooth transition between them must be faked in some way (simple blending?)
I find this reasonable because it is not a matter of color changes what is important is a matter of what structures you actually see. Different wavelenght vision can make objects that are invisible in the sky outshining the rest and gas cloud structure could become transparent in infrared ect... so IR and UV textures (or textures for near IR, far IR and the same for UV) would be quite usefull. For planets you wouldn't need to add different textures (it would be suffient with the DoctorOfSpace's solution) because at relativistic speeds the details of the planets would appear and dissapear in less than a second or two in the screen. In stars Vladimir have said that is easy to perform so the real issue here is to add this textures only at galactic scale (a bit of work but maybe not so much).
Maybe with that we could see a colorfull galactic differentiated structure while moving across the stars (that would change also). And maybe we could add two or more things to simulate preliminary this kind of spectacle: for example, the thin accretion disks around black holes that Vladimir is working on emit powerfully in X-rays. If you exit at high relativistic speeds the galaxy, then looking backwards (from the direction of motion) you could see bright dots revealing the black hole's redshifted X-rays.
Also, at usable speeds (interstellar travel within few seconds => 0.999..999c) the "field of view" will collapse in few pixels in front of user, so no relativistic effects could be observable.
I don't quite understand this, in the A Slower Speed of Light the darkness dosen't arrive even at close light speeds. As I understand it, the light coming directly from where you are moving towards experiences a blueshift making you to loose the visible spectrum there but permiting to see in the visible the infrared frequencies. At the oposite side you will see the redshifted spectrum of UV in your visible frequencies. Watching at the sides of your motion you will see the visible everyday sources because the component of your motion in that direction is zero. The rest of angles is a gradient across the frequencies. That as I have learned it. Maybe there are more subtle effects that I don't remember. Perhaps at far UV the spectral band of visible is to short to show many sources and thus all things become black except for small dots (but for gamma rays and x rays chandra shows quite awesome things), or maybe the at far infrared or microwaves the sources have very little power, I don't know if this quiet zones of the EM spectrum could generate that darkness you are mentioning.
The issue about clocks is also a moot issue as the engine supports speeds greater than c and time acceleration which is perfect.
Think of it like this
As you accelerate closer to c in SE the relativistic effects would kick in and the engine time would accelerate. This way you could speed things up locally as it would be perceived by the user and in engine it would be treated like normal time acceleration. At 1c all journeys would be instant but the engine would adjust the global time by however far you traveled. At 0.99c you would have all those crazy colors and distorted view and engine time would accelerate to match what you would experience on board a craft going that fast. This way if you flew to alpha centauri at 0.99c as you accelerate you would get the full distortion effect, engine clocks would speed up, physics would speed up, and you would arrive in a few weeks/months from your perspective or if you pushed to 1c the trip would be instant and the engine clocks would jump to 4.3 years in the future.
This issue is complicated. I don't know if I'm wrong but I don't agree with your perspective. The problem is not the relativity of time but the simultaneity of events. There could be a universal time clock (like that we have now) from where all procedurall and non procedurall events could have their time-coordinate and then clocks in every corner of the universe that would shift acoording to your motion. It's not as simple as you arrive to another point of the universe changing the speed of the flow of time only. The fact is that the traveler would see events happening (galaxy collisions, supernovae, and other things) in different directions around it and would experience (depending on what direction you are watching, on speed and motion vector) this events happening in different moments relative to one and other. For example, maybe you are moving with a galaxy at cero relative velocity and you see supernova A happening and then supernova B but if you where traveling at relativistic speeds, depending on where the sources are ect... you could even see supernova B happening before supernova A. Maybe you could see the shadow of an eclipse without the object occulting the star because the events could be separated in time from your relativistic perspective. So different clocks have to be placed in different parts of the procedural universe and they should change their flow acoording to location and relative orientation of your motion.
Am I right? maybe I'm a bit confused also. Relativity is something I'm going to do with true maths the next year at university so maybe my theoretical basis is a bit missleading.