ABSTRACT
The idea of"information" (Ch. 6) is becoming very important in chaos theory. As long as there is some relation between two variables, one contains information about the other. Take, for example, the Christmas season. Sales of toys are highest by far at that time of year. Looking at a list of the volume of sales throughout the year, we can immediately recognize the Christmas season, even if we're not given any associated months of the sales. Measuring just one variable (either month or sales) gives some information about the other. (Low sales indicate that it's not Christmas time, and vice versa.) Similarly, the amount of water in a river (Ch. 9) typically rises to a peak in the springtime, then recedes to an annual low in late summer (at least where I live). A few sequential measurements of just one of the variables (either time of year or streamflow) give us some information about the other.
