The Arecibo message was a signal emitted through a radio telescope in 1974. It was transmitted as an exercise to show technological advances of humanity and how difficult communication with other civilizations would be. This Demonstration lets you:
• view the representation of the signal,
• hear how the signal would sound if transformed into sound waves, and
• create other messages compatible with the structure of the Arecibo message.
Open up and slow down the "bit position" slider to about half the original speed, then press the play button.
Arecibo's message is composed by arranging 1679 bits into a rectangle of 23 rows by 73 columns. This arrangement was selected because 1679 is the product of two primes, so it might be natural to lay the bits out as a rectangle. The message contains information on the components of nucleotides, the DNA double helix, the planets of the solar system, the Arecibo telescope, and an image of a human.
This Demonstration lets you encode not only the original Arecibo message but other messages, such as Euler's equation, a pretty generic building, a face (worried about an upcoming alien invasion), and the legendary Sputnik satellite.
The Demonstration resizes the input image (in the case of the Arecibo message, the image remains the same size) to fit the 23×73 dimensions and then binarizes it so that the remaining image is an array of ones and zeros. This new image is then transformed into an array of musical notes ("C" is used for a zero while "A" is used for a one) and then it is converted into a binary sound.