Open source relativistic game engine by MIT game lab

[azorni]

Check this out:
http://gamelab.mit.edu/games/a-slower-speed-of-light/

Wouldn't it be cool if we could travel in Celestia at relativistic speed and see accurate relativistic effects?

[Chuft-Captain]

I like the idea as a demonstration, although it would be more applicable if seen in Celestia at truly relativistic speeds.

I would think that Fridger would be interested if it truly was open-source.
They make some claims in their video that it's open source, but I saw no links to source code (unless it's included in the download?)
Also, their EULA prohibits derivative works, which seems a little in-consistent with the principles of open-source.
They seem to be taking a "LOOK but don't USE" stance, which sort of makes you wonder why they would publish the code at all?

In any case, I suspect Fridger may have something similar in the pipeline for his Celestia.Sci (Correct me if I'm wrong Fridger )

[t00fri]

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In any case, I suspect Fridger may have something similar in the pipeline for his Celestia.Sci

YES!

and in addition general relativity for cosmological visualisation.

Here is a nice academic site from Prof. Ute Kraus and her group @ Univ. Hildesheim/Germany about visualizations of special and general relativity.

http://www.spacetimetravel.org/

Have a look at the many videos they have done. Unfortunately the German site is more up-to-date.

Fridger

[azorni]

http://www.spacetimetravel.org/

Have a look at the many videos they have done. Unfortunately the German site is more up-to-date.

Well I'm kind of disapointed by what I see there. I don't remember where I read that, but I once read that when travelling at a relativistic speed, stars in the sky gather in a narrow angle in front of the traveler, just in the motion axis. This is due to the fact that waves coming from asides or even behind seem to be coming from the front (I once managed to understand why, but I forgot later. It's not easy to understand).

In this video for instance it doesn't seem to be so.

Apart from the doppler effect, doesn't the sky look different at near light speed?

PS. I remember now.

Say a traveler travels at v in the x direction. A star very far away in the y direction emits a plane wave exp j(ky - t) [c=1]

In the reference frame of the traveler, we have y' = y, t' = gamma*(t - vx), so the plane wave becomes:

exp j(ky' - (t'/gamma + vx')) = exp j( (ky' + vx' ) - t'/gamma )

and it's clear that the propagation vector of the wave is now slightly pointing towards the x' direction. (Also, the angle seems to depend on the wave length of the light, which is weird)

PS#2. Ok found a simulation including it: http://apod.nasa.gov/apod/ap111018.html
It's called angular compression.

[t00fri]

Well I'm kind of disapointed by what I see there.

azorni,

I can assure you that the research group around Prof. Ute Kraus knows exactly what they are doing! Certainly, they didn't forget the basic and familiar angular compression. Since the Poincare group of transformations does NOT include the conformal symmetry group, angles change under Lorentz transformations.

I think the starting picture of the video you quoted displays a considerably enhanced star density in a small angular region around the target (the Sun), which may well be the effect (assuming that the actual star density was isotropic). Unfortunately, I cannot watch that video for now since I am basically offline until tomorrow. I only have a slow mobile connection right now. The NASA video you quoted is blocked for people from Germany, sigh...

I like the visualizations by that Univ. Hildesheim group that are academic in spirit, mainly addressing to (astro)physics students. Instead of presenting mere "eye candy", the approach is to visualize separately (as much as possible) the three basic effects of relativistic spacetime travel:

rotation
distortion
color & brightness changes

and make the students UNDERSTAND their origin. I think the extended explanations going with the various videos are quite insructive.

Fridger