http://en.wikipedia.org/wiki/Minkowski_diagram [2]
http://www.astro.ucla.edu/~wright/st_diags.htm [3]
http://www.phy.syr.edu/courses/modules/LIGHTCONE/events.html [4]
http://arxiv.org/ftp/physics/papers/0703/0703002.pdf [5]
http://www.physics.byu.edu/faculty/allred/222%2011/minkowski%2011.pdf [6]
http://www.trell.org/div/minkowski.html [7]
Links
[1] https://hootsgo.org/?q=node/6417
[2] http://en.wikipedia.org/wiki/Minkowski_diagram
[3] http://www.astro.ucla.edu/~wright/st_diags.htm
[4] http://www.phy.syr.edu/courses/modules/LIGHTCONE/events.html
[5] http://arxiv.org/ftp/physics/papers/0703/0703002.pdf
[6] http://www.physics.byu.edu/faculty/allred/222%2011/minkowski%2011.pdf
[7] http://www.trell.org/div/minkowski.html