Reddit mentions of Worlds in Collion

Seth Lloyd -- Programming the Universe: A Quantum Computer Scientist Takes on the Cosmos

Gregory Chaitin -- How real are real numbers? -- this paper, and all of Chaitin's writing, has been hugely influential on my thinking

I haven't read it, but I have heard Nick Bostrom's Superintelligence highly recommended. Ditto for Max Tegmark's Life 3.0.

I also recommend reading anything by David Chalmers, just on general principle. The Conscious Mind is a good place to start. I find his methods of contemplating the problems of consciousness to be more robust than the standard fare. The hard problem of consciousness (as Chalmers has dubbed it) suggests that there is something fundamental about what we are that modern science has completely failed to capture, even in the most sketch outline.

To go further, I recommend reading in a mystical direction. Specifically, ask yourself why there are patterns in mystical traditions that have arisen independently? And these are not just vague, hand-wavey correlations, but very specific, detailed correlations like the anatomical descriptions of dragons as winged serpents that slither through the sky, and so on. See Immanuel Velikovsky's Worlds In Collision and subsequent works for more along these lines.

If this is getting too far afield then you can ask yourself an even more basic question: why do we experience dreams and where, exactly, are these experiences happening? If you say, "it's all just remixes of past experiences being sloshed around in your skull like those #DeepDream images", how come they are so specifically odd and out-of-character? I have had extended conversations in my dreams with people I know (and people I have never met) and the detailed character of these conversations is far beyond anything that my pathetic brain could cook up, even by remixing past experiences. In short, when I dream, I am sometimes having genuine experiences, just not the kind of experiences I have in my waking body. Anyone who has had a lucid dream (I have experienced this a handful of times) is acutely aware of the fact that dream-space is some other place than the meat-space we occupy during waking hours. Where is this other place and why does it exist? What does it really mean to have conscious experience?