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Understanding our world(s)... For a great look at the history of the scientific revolution, make sure to read The Invention of Science, by David Wooten. To try and get your mind around theoretical physics, astrophysics and even time travel, read anything by Micheo Kaku. For a head-trip look at both science and spirituality, check out Rupert Sheldrake's Science and Spiritual Practices.
But really, any of these books will illuminate, identify and analyze many aspects of the universe.