Plus, Minus: A Gentle Introduction to the Physics of Orthogonal

For those of you who aren't familiar with Egan's work, I can't recommend it enough. All good scifi indulges in world-building, but Egan's is the most scientifically well-thought-out I've seen, as well as containing some very plausible depictions of post-humanity.

Many of his works are available in their entirety on his (delightfully 90's) website, http://www.gregegan.net.

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...

I'm actually a bit miffed because I bought the first two books of the Orthogonal series from BaenEBooks [ http://www.baenebooks.com/s-164-greg-egan.aspx ], then discovered that due to problems with Night Shade Books, I couldn't get "The Arrows of Time" as an ebook too.

Unfortunately, other ebook vendors like Google Play are not selling a DRM-free version of that book.