On: Plus, Minus: A Gentle Introduction to the Physics ...

[sxp]

Egan also has a nice intro to real relativity: http://gregegan.customer.netspace.net.au/FOUNDATIONS/index.h...

Also, Permutation City (deals with the philosophy of uploaded minds) and Diaspora (also related to some of the philosophy of uploading) are amazing novels.

http://gregegan.customer.netspace.net.au/DIASPORA/DIASPORA.h...

http://gregegan.customer.netspace.net.au/PERMUTATION/Permuta...