Assignment 4
CETI
Due: September 2, 2010

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The Search for Extraterrestrial Intelligence (SETI) is a passive attempt to search for extraterrestrials. It involves listening. SETI has as its nonpassive counterpart Communication with Extraterrestrial Intelligence (CETI). The issue for SETI is simply knowing whether or not extraterrestrials have communicated with us. Later, we determine what the extraterrestrials are saying. For CETI, the key is to devise a message which can be beamed into space and which an extraterrestrial would have a fighting chance of understanding. This task is not so simple. Below is a trial message made by Frank Drake (using a method he believed to be promising) which could be sent to an extraterrestrial civilization.

1. Thinking up an understandable message is very difficult. Consider a message constructed by Frank Drake, which he envisioned could be beamed into space. The radio signal was composed of a string of 551 bits of information, each bit either a "zero" or a "one." The sequence of 0sand 1s is shown below. It is actually a single string of numbers running in rows from left to right. The string is only divided into rows to make its presentation easier.

Imagine you are an extraterrestrial who received this message and determined, firstly, that the message was sent from the Earth, the third planet from the star in our little Solar System, and the the message was from an intelligent civilization. You next want to transform the radio transmission's sequence of zeroes and ones into a picture (message) which you can interpret. Your first task is to figure out how to divide your sequence of ones and zeroes into a two-dimensional grid (using the graph paper below). How should you divide up the string? How many rows and how many colums should there be in your grid? Is there a best way? How did you finally choose to divide up the string of bits?

2. After you decide how to divide the string of bits, transfer the message to the grid (graph paper below) to form a picture. For the squares which contain ones, blacken the box. For the squares which contain zeroes, leave the box white.

2. What do you make of the message? What information is being transmitted in the message?

3. Was this a sensible attempt? If you were asked to improve this attempt to communicate, what would you suggest?