Looking back over the advance of physics over the last two hundred years, it's staggering to realize how much our world view has changed. As a science fiction writer, I'm always trying to imagine how much more things might change in the coming two centuries. The really hard thing to anticipate is the completely game-changing advances that occur every so often.
My sense is that, for one thing, we won't be using chip-based computers in two hundred years—any more than we use mechanical calculators now. That's why, in my recent novels Postsingular and Hylozoic, I've been speculating about a world in which our computations escape from our machines and filter into our ordinary matter.
Nick Herbert is one of my favorite offbeat physicists. One of his papers in particular is something I've thought about a lot over the years: "Holistic Physics, or, An Introduction to Quantum Tantra." Here Nick argues that our conscious minds display some of the same features as quantum mechanics. When we're not thinking about anything in particular, our thoughts evolve in a continuous, multi-universe kind of way—but when we focus on something, we carry out something like the quantum collapse that characterizes the process of measurement.
[Brain models from the Collection of Historical Scientific Instruments at Harvard University.]
As I've been saying, I think it's at least in principle possible that the quantum computations in ordinary matter might be capable of carrying out these same kinds of processes—which we normally associate with living, conscious minds. And Nick's paper helps you to think about this idea.
David Deutsch wrote a deep and technical paper about the topic of computation in arbitrary pieces of matter, called "Quantum theory, the Church-Turing principle and the universal quantum computer."
The basic idea is that quantum mechanical systems can act as universal computers, and it's generally believed that any universal computer can emulate a human mind (given the right program, and, aye, there's the rub).
One of our big problems is that we still have such an imperfect notion of how to build a software system that's like a human mind. The best idea along these lines that I've seen in the last few years is in the book On Intelligence, by Jeff Hawkins and Sandra Blakeslee.
Two more rich sources for futuristic ideas.
(1) The arXiv.org site—for instance look at their New Papers on Cosmology and Extragalactic Physics page. It blows my mind that you can so easily access all these wild new papers, easily readable in PDF form. Even if, for the average person, a lot of the writing is incomprehensible gibberish (like the backwards neon sign shown above), you can skate through and pick up some great concepts and buzzwords.
(2) The physicist John Baez's pages. Baez is a deep thinker and a gifted popularizer, adept at imparting the true strangeness of this world.
It's liberating to realize that, as always, we're very much on the edge of knowing what's really going on.