Having just finished a magical realism novel I need some hard Science fiction - The hardest!

Per this thread I just finished"Little, Big" by John Crowley and need some hard science fiction to get me straight. What’s the best, hardest science fiction novel you can think of? Hard like ebony wood, hard like tungsten carbide. Hard edged characters, focused plots, maybe some sex. Hard no regrets sex.

Done any Alastair Reynolds? I’d say easily an 8-9 on the Mohs scale.

Oh, and I just picked up Rainbows End by Vinge. Also recommended.

Greg Egan. From wikipedia

You could take a look at Schild’s Ladder

I highly recommend Diaspora by Greg Egan. In the first few chapters all biological life on earth is destroyed by a gamma ray burst. Then the story begins…