Linux NetMag #3
Titel: Theory of Relativity with Lightspeed!
URL: http://www.linuxnetmag.de/de/issue3/m3lightspeed1.html

spaceship
What would it look like to you if a car passed you at nearly light speed?
This incredible experiment can be simulated with your computer!

Curious Space-Time

With high (very high) velocity things happen that are not obvious at first thought. The best known effect is the Doppler effect:
Objects moving away from us appear more red than a resting object and objects coming nearer appear more blue. Stars that are far away fly away from us and their spectrum moved or shifted a little bit into the red.
The classical analogy is the change of sound like an orchestra playing on a train. While the train moves toward your position, you hear them playing a higher sound than they are and if the train passes you the sound will be deeper. (The apparent change of sound and light are analogous in their phenomenon, but have completely different physical equations since sound needs a medium to propagate and light does not.)

Another effect is the Lorenz contraction. A fast moving object looks squeezed in the direction it moves in. This contraction increases with an increase in velocity. For a fast moving visitor the surrounding looks contracted.
Similar effect happens to the time scale when comparing the moved and fixed system. This is also shorter or longer depending on the system in that you are. This effect is called time dilation and cannot be simulated by computers, only calculated.

The frontlight effect causes a lighter or darker appearance of the object depending on the direction you are looking. The brightness changes because the object moves nearly as fast as the light.

Maybe the most unknown but very impressive effect is the optical aberration of an object. This causes a rotation and distortion of the object and it can be possible to see more objects than usual.

This is the way a cubic

normal velocity

looks different with 0.995c:

velocity = 0.995c


Lightspeed!

Lightspeed simulates all these effects in real-time using imported objects saved in the 3ds (3D-studio) format. A cubic with its 12 connections and 8 balls (one in each corner) has already been included. Many more objects can be downloaded at the author's homepage like a Chevy or a Hover. These objects have many polygons and need much more time for calculation to show a smooth slideshow.
If you have chosen an object, you are able to enter a velocity in the units m/s, km/s or c (c = light speed) and look at what changes. You are also able to deactivate the effects separately (Lorenz contraction, frontlight effect, optical aberration) to see the influence. The intuitive GTK frontend should make it possible to everyone to handle this program even if you did not have any knowledge about the Theory of Relativity.

This is a very nice program that invites you to play with its many options.

Links:

Lightspeed homepage: http://fox.mit.edu/skunk/soft/lightspeed/