Recognizing a Message
As light travels through space, its intensity decreases by the square of the distance from which it came. Since radio waves are a form of light, this means that when a radio signal is detected over a large distance, it is dramatically weaker than when it was transmitted. This becomes a substantial obstacle when sending or receiving signals over the vast distances of space. In particular, the radio signal becomes so weak that it is difficult to detect the signal against background cosmic noise sources. It is like trying to hear a whispering child in a room full of shouting adults.
When creating a radio message to communicate through space,
the message should be sent over a narrow bandwidth and code information through
variations in radio frequency. When
compared to cosmic sources of radio noise, a narrow bandwidth will provide the
best chances of detection. A team at the
The optimal method for transmitting a radio message is by pulsing the signal. This way the radio energy is sent in small, concentrated bursts and is easier to pick out from background noise. Pulsed signals correspond directly to the digital way that information is stored and transmitted on FM radio stations, CDs, and computers. Just as the information stored on our computers can be large and extremely complex, an enormous amount of information can be conveyed with a sufficient number of binary elements, or bits. Each bit is a signal which is either 1 or 0, on or off. We might hope that any creature with sense receptors is aware of some version of the distinction between bright and dark, hot and cold, loud and quiet, or 1 and 0.
In order to increase our chances of successfully recognizing an extraterrestrial message, it is helpful to consider what message we would send into space. We might first think of sending an eloquent statement describing our hopes and dreams, but in doing so we risk falling into an anthropocentric trap. To transmit a universal message, the message should be as free from cultural influences as possible. Some have suggested using a language based on mathematics, arguing that it would be able to convey many universal truths. For example, artificial intelligence expert Marvin Minsky has explored the behaviors of all possible artificial processes by creating all possible computers and their programs. This is the computational equivalent of the Miller-Urey experiments — taking the simplest processes and seeing what complexity arises. Minsky created thousands of computational machines, most of which stopped without accomplishing anything. A few got trapped in circles and senselessly repeated the same steps over and over. However, a few performed a counting operation — essentially, they "invented" arithmetic! Dutch mathematician Hans Freudenthal has developed LINCOS, or Lingua Cosmica, a language designed for universal discourse. This language is designed to convey mathematics and physics in a coded form.
Have the messages we have sent so far matched the ideal of a
universal language? In 1974, we used the
If other civilizations in the universe have been as
forthcoming as ours by sending a message, we may not be able to decipher
it. However, we are fairly confident
that we will be, at the very least, able to recognize a message of alien
origin. For example, even if the alien
recipients of our
WAYS OF REPRESENTING DATA
THE ORIGIN OF LIFE ON EARTH
GALAXY DISTANCE INDICATORS
AGES OF GROUPS OF STARS