Gelernter's wonderful book is perceptively subtitled, "Or the Day Software Puts the Universe in a Shoebox: How It Will Happen and What It Will Mean."
Here's an excerpt from Sohodojo's book recommendation of 'Mirror Worlds':
Theodore Kaczynski, convicted Unabomber, was willing to kill to keep David Gelernter from writing another book as good and important as this one. Mirror Worlds is the most important book about the Internet that you can read. What is even more amazing? Mirror Worlds isn't supposed to be about the Internet.
Ten years after its publication, the really impressive thing about Mirror Worlds is what Gelernter and all the rest of us didn't foresee. The Mirror World is a magical Looking Glass; a transforming two-way mirror. The rapid growth of the Internet and its associated impact on the emerging global economy means that the model has become the system itself. The outside world is changing to reflect our lives inside the wired, network world we live in... not the other way around.
We've recommended that Jelal read this book at the beginning of his internship because it makes such a powerful case for the remarkably simple yet profound idea that something qualitatively special happens when you take a simulation of something and hook up its input and output feeds to the actual system the simulation simulates! You get the Big Bang birth of a Mirror World!