Diaspora.

Another interesting "explore an idea" novel from Greg Egan around physically embodied versus reality simulating virtual versus no bounds virtual living. But this one didn't engage me as strongly as Egan's books usually do. Mainly I think because the discussion of the differences between the two virtual modes of living went on to long for me. I understand why that length and depth was needed for reasons critical to the plot, but it was too much for me.

Neutron stars, gamma rays, curvature, multiverse, Euler, Planck, six-dimensional space and the gang are at it again! This time in a story which, despite not being exactly original, is challenging and captivating. Had to do a ton of googling while reading, physics is not my cup of tea, and have enjoyed myself. Cannot but recommend.

I've seen it described as "diamond-hard SciFi", it might even be an understatement. It starts off being confusingly abstract. After ~15% it gets more coherent, slightly more corporeal, though never entirely so.

Even through its abstract and detached universe, it revolves around modern issues of reality, subjectivity of perception and even memetic reality bubbles.

There's a lot to get from this, provided you can keep your mind clear enough to absorb the weirdness of it all.