Artificial And Natural

- Prithwis Mukerjee

QUANTUM MECHANICS IS a subject that has the strange property of simultaneously being logically rigorous and yet completely counter-intuitive. So much so, that even a towering intellect like Einstein could never bring himself to accept its principles even though products based on the same exist all around us. The earliest oddity, identified by Schrodinger, one of the founders of quantum mechanics, is about a hypothetical cat that is neither dead nor alive until someone actually observes it. A similar oddity is that of quantum entanglement, where the behaviour of one particle is instantly affected by the behaviour of another particle, however distant it may be—an example of “spooky” action-at-a-distance. Explaining these phenomena is beyond the scope and temerity of this article and so the reader would have to accept them here in good, almost religious, faith and carry on with the belief that such phenomena have been observed and explained by scientists under the most rigorous experimental circumstances.

Any programmable digital computer that we use—the desktop, the smartphone or the ones at Google—is based on a finite state machine (FSM). It can, at any instant of time, be in one of a large, but finite, number of well defined states. The state of an FSM is defined by the value stored in each of its memory locations and we know that these can either be 0 or 1. So an FSM with, say, 16 bits of memory could in principle be in any one of 216 states. Any instruction to the FSM changes the value of one or more bits and the FSM moves to a different state. An FSM along with the ability to read binary input, from an infinite tape, and write back on the same tape, is the Turing machine that is the theoretical basis of any modern computer.