## Mathematical and Computing Sciences Faculty/Staff Publications

Book Chapter

2012

#### Abstract

In my classes on the nature of scientific thought, I have often used the movie The Matrix (1999) to illustrate how evidence shapes the reality we perceive (or think we perceive). As a mathematician and self-confessed science fiction fan, I usually field questions related to the movie whenever the subject of linear algebra arises, since this field is the study of matrices and their properties. So it is natural to ask, why does the movie title reference a mathematical object?

Of course, there are many possible explanations for this, each of which probably contributed a little to the naming decision. First off, it sounds cool and mysterious. That much is clear, and it may be that this reason is the most heavily weighted of them all. However, a quick look at the definitions of the word reveals deeper possibilities for the meaning of the movie’s title. Consider the following definitions related to different fields of study taken from Wikipedia on January 4, 2010:

• Matrix (mathematics), a mathematical object generally represented as an array of numbers.

• Matrix (biology), with numerous meanings, often referring to a biological material where specialized structures are formed or embedded.

• Matrix (archeology), the soil or sediment surrounding a dig site.

• Matrix (geology), the fine grains between larger grains in igneous or sedimentary rocks.

• Matrix (chemistry), a continuous solid phase in which particles (atoms, molecules, ions, etc.) are embedded.

All of these point to an essential commonality: a matrix is an underlying structure in which other objects are embedded. This is to be expected, I suppose, given that the word is derived from the Latin word referring to the womb — something in which all of us are embedded at the beginning of our existence. And so mathematicians, being the Latin scholars we are, have adapted the term: a mathematical matrix has quantities (usually numbers, but they could be almost anything) embedded in it. A biological matrix has cell components embedded in it. A geological matrix has grains of rock embedded in it. And so on. So a second reason for the cool name is that we are talking, in the movie, about a computer system generating a virtual reality in which human beings are embedded (literally, since they are lying down in pods). Thus, the computer program forms a literal matrix, one that bears an intentional likeness to a womb.

However, there are other ways to connect the idea of a matrix to the film’s premise. These explanations operate on a higher level and are explicitly relevant to the mathematical definition of a matrix as well as to the events in the trilogy of Matrix movies. They are related to computer graphics, Markov chains, and network theory. This essay will explore each of these in turn, and discuss their application to either the events in the film’s story-line or to the making of the movie itself.