Understanding Penrose Diagrams - Insight & Explanation

[benk99nenm312]

Hey. I was hoping that someone(s) could give me some explanation and insight into the Penrose Diagram shown below. Any links to good sites would be great, as I have not found what I am looking for.

I guess, one of the things I am really wondering is: why is there a circular like distortion in the center? But in order to understand that, I assume I would need to understand the whole premise of the idea, so..

Thanks in advance.

 

[robphy]

Try
www.pitt.edu/~jdnorton/teaching/HPS_0410/chapters/black_holes_picture/