Ask HN: Good books on computation

I've been mulling the notion of computation. I'm familiar with the lambda calculus and Turing machines. For example I understand insofar that beta reduction is computation. Or the movement of tape is computation. Or the common analogy that information is steady state in the energy space and computation is the work done in changing these energy states.

However, the more I try to pin down an exact definition of a computation the more it slips away like star systems in Tarkin's grip. I seem to be missing some subtle understanding of computation.

I want recommendation on books that will help me understand computation in the way Jürgen Schmidhuber or Stephen Wolfram does. Some math is preferred, but without it being text-book dense would be nice.

I've thumbed through Sipser but it seems a bit obsessed over computational complexity. What I'm looking for is slightly more towards the pancompuationalist works.

Any recommendations is welcome