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Forum » SpaceEngine » Feedback and Suggestions » Relativistic Effects Discussion
Relativistic Effects Discussion
SpaceEngineerDate: Saturday, 06.12.2014, 22:31 | Message # 31
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Stars spectrum is modelled analytically already, so it would be easy to redshift or blueshift it. You may already do that in the edit mode (Shift-Home or Shift-PgUp, don't remember). Galaxies and planets are much more complex, but procedural ones could be done relatively easy. The most hard thing is real objects - M31, Earth etc. We could use a set of real textures for some wavelengths, but smooth transition between them must be faked in some way (simple blending?)

But the most complex thing, what probably cannot be solved, is time travel to millions and billions of years. Modelling of galaxies collision is impossible in procedural engine, galaxy rotation is almost impossible, stars and planets evolution is almost impossible, taking into account requirement of REAL TIME makes all this impossible.

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.

PS: this thread and all other ones about this subject must be merged together.





 
DoctorOfSpaceDate: Sunday, 07.12.2014, 01:05 | Message # 32
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Merged old threads about this into 1 and renamed thread to Relativistic Effects Discussion




Why not use the 3D anaglyph system from 0.9.7.2 for color shifting?



If you could automate the process of the shifting it would look fairly convincing alongside the visual distortions.





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HarbingerDawnDate: Sunday, 07.12.2014, 06:08 | Message # 33
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Quote DoctorOfSpace ()
Why not use the 3D anaglyph system from 0.9.7.2 for color shifting?

It's very cheap and quite unrealistic. People who know what relativistic effects look like would be unsatisfied, and people who don't would be misled.





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FastFourierTransformDate: Sunday, 07.12.2014, 23:31 | Message # 34
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Quote DoctorOfSpace ()
First you could do it with color changes and not have to have UV or IR and still pull it off (semi-)realistically

Quote
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:

Quote
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.

Quote
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.

Quote DoctorOfSpace ()
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.
 
DoctorOfSpaceDate: Monday, 08.12.2014, 00:05 | Message # 35
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Quote FastFourierTransform ()
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.


All of which is incredibly complex and not required to represent the basic effects of relativistic travel like what is seen in A Slower Speed of Light.

What I have suggested is a way to represent relativity within the currently limited program. What you are suggesting would take at least another decade of straight coding and development and a near 1:1 representation of physical laws. SE does not need rotating galaxies, aging stars, and planetary evolution to implement relativistic effects. All of those things are not required to represent relativistic spaceflight, visual distortions, color shifting, or physics/time acceleration. Sure it isn't perfect, but most of the features in SE aren't perfect either.

SpaceEngine is currently a single player first person experience only, which means my suggestion for basic relativistic implementation would work fairly well.





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WatsisnameDate: Monday, 08.12.2014, 06:57 | Message # 36
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Quote FastFourierTransform ()
I don't quite understand this, in the A Slower Speed of Light the darkness dosen't arrive even at close light speeds.


This is because in Slower Speed of Light's standard gameplay, you are not going close enough to the speed of light to see this effect (called relativistic beaming). The Doppler shift effects become apparent at lower speeds than the beaming does. Once you beat the game by collecting all the things, the fraction of c that you can achieve is boosted significantly so that you can experience the beaming more clearly. (I think they also disable the doppler shift at the same time.)

Hence this actually serves to emphasize the point that SpaceEngineer was making: when you're going at extremely large fractions of c, the beaming effects are so severe that you can barely even tell what's happening and navigation becomes nearly impossible. At speeds necessary to do interstellar or intergalactic flights in seconds or even minutes (99.99etc percent of c), your field of view would be only pixels across.





 
CesrateDate: Monday, 08.12.2014, 09:04 | Message # 37
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Well, can any structures survive under the impacts of small meteoroids at 0.01c?
 
WatsisnameDate: Monday, 08.12.2014, 09:50 | Message # 38
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The way your question is worded (you have four ambiguities), the answer will always be yes. The answer to the question I think you mean to ask is "Impacts with particles at relativistic speeds would be a serious issue."

For speeds that aren't too close to the speed of light (0.01c isn't that close), you can fairly safely use the approximation that KE=1/2mv2, which implies that impact with a grain of sand would deliver on the order of megajoules to the target area. This would easily punch a hole through most materials.





 
CesrateDate: Monday, 08.12.2014, 15:36 | Message # 39
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Watsisname, first I don't think it should be moved to this thread, as it's not on a relativistic velocity; then I would like to question about the possible shielding of spaceship to endure an impact of dusts or small meteoroids.
 
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