What are the best free software options for visualizing relativity concepts?

[ehrenfest]

Does anyone know of a good, free special and general relativity software package that would allow me to do things like visualize spacetime warping or length contractions or lightcones?

 

[cesiumfrog]

Could you give some more detailed examples of the typical types of thing you would like to do with the software, please?

 

[robphy]

Are you trying to visualize spacetime diagrams?
or visualize graphical plots of relevant subspaces?
or visualize optical effects?

 

[ehrenfest]

I don't really know what the software is capable of. But for a start, it would be nice to visualize spacetime diagrams.

 

[neutrino]

But for a start, it would be nice to visualize spacetime diagrams.

I'd like that too. :)

 

[robphy]

One package that might be worth looking at is
http://www.opensourcephysics.org/apps/gr_programs/special_relativity/index.html
which is Java based... and can probably be customized.
However, there might be some setup required.

For simple viewing and interaction:
www.its.caltech.edu/~phys1/java/phys1/Einstein/Einstein.html
http://physics.syr.edu/courses/modules/LIGHTCONE/java/TwinParadox.html (my ancient applet)

There are some other relativity applets around... but they don't draw spacetime diagrams... but rather spatial diagrams, which have some but only limited use.

The visualizations I do are in Python and in Java... but they're not ready for general usage by others [i.e. they work for me to some extent, but isn't friendly enough for others to use for their own purposes yet].