Universal Cellular Automata Machine (UCAM)

Ed Fredkin, a Physicist from Massachusetts Institute of Technology, has proposed that the worlds we experience directly through intuition and indirectly through science, are programs running on a Universal Cellular Automata Machine. Like the cellular automata (CA) simulations that we write in class, local interaction and knowledge lead to global interaction and knowledge at progressively higher scales of abstraction. For Fredkin, the smallest lengths and smallest timesteps in physics constitute the "grid spacing" and "frames" on which successive states of the world are computed. According to Fredkin, this grain size is the Planck length and this time interval is the Planck time. All phenomena in the universe are emergent properties of this UCAM including the so-called "scientific laws."

Because the programs that we write can run on any computer, not just a PC or a Mac, but all those other kinds of "computers" that Danny Hillis mentions in his book, Pattern in the Stone, it follows as a corollary that the objects in the program have no knowledge of the medium of the underlying machine. Fredkin extends that idea to the UCAM, saying that we can we can have no knowledge of the ultimate underlying structure of the Universe. This claim places new epistemological challenges and limitations on science.

Can a program come to understand the machine on which it runs? If the Universe is a UCAM, can we come to understand its underlying structure?