In a kind of postscript, Ellie, acting upon a suggestion by the senders of the Message, works on a program which computes the digits of π to record lengths and in different bases. Very, very far from the decimal point (10^20) and in base 11, it finds that a special pattern does exist when the numbers stop varying randomly and start producing 1's and 0's in a very long string. The string's length is the product of 11 prime numbers. The 1's and 0's when organized as a square of specific dimensions form a perfect circle.

The extraterrestrials suggest that this is an unmistakably intelligent artifact, an artist's signature, woven into the fabric of space. It is another Message, one from the universe's creator. Yet the extraterrestrials are just as ignorant to its meaning as Ellie, as it could be still some sort of a statistical anomaly. They also make reference to older artifacts built from space time itself (namely the wormhole transit system) abandoned by a prior civilization. A line in the book suggests that the image is a foretaste of deeper marvels hidden even farther within Pi. This new pursuit becomes analogous to SETI; it is another search for meaningful signals in apparent noise.

This is neato.