I have to second this. It took me years to thoroughly grasp some of its parts (and I have a math background) but Diaspora is without a doubt my favorite book of fiction.

The first chapter of the novel is particularly approachable & worthwhile. It's titled Orphanogenesis and is a beautiful, detailed (~30 page) account of the digital birth of a new AI consciousness, from embryo to newborn to gaining self-awareness.

Next year several Greg Egan's books will be reprinted. Diaspora comes out January 6, 2015!

http://www.amazon.com/Diaspora-A-Novel-Greg-Egan/dp/15978054...

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If you want a softer approach to Egan's fiction, check out his short stories. Reasons to be Cheerful is my favorite one as well as Egan's. It's part of the Luminous collection, available as a $3 kindle ebook:

http://www.amazon.com/Luminous-Greg-Egan-ebook/dp/B00E84BABW...

Alas no. I read a range of sci-fi but am not aware of other authors who write such amazing speculative fiction. He really takes sci-fi ideas to unpredictable yet believable conclusions. It is real hard sci-fi.

If you do discover similar authors, please let me know.

Recommended reading:

All his short stories are amazing. I'd highly recommend them:

http://www.amazon.com/Luminous-Greg-Egan-ebook/dp/B00E84BABW

http://www.amazon.com/Axiomatic-Greg-Egan-ebook/dp/B00FDWOBZ...

Some of his novels are hit and miss, but certainly worth checking out. This is probably my favourite:

http://www.amazon.com/Permutation-City-Greg-Egan-ebook/dp/B0...