Communication with Extraterrestrial Intelligence

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CETI (Communication with Extraterrestrial Intelligence, or METI, Messaging to Extraterrestrial Intelligence) is a branch of SETI research that focuses on composing and deciphering messages that could theoretically be understood by another technological civilization. The best-known CETI experiment was the 1974 Arecibo message composed by Frank Drake and Carl Sagan.

CETI research has focused on three broad areas: mathematical languages, pictorial systems such as the Arecibo message, and algorithmic communication systems (ACETI).

Contents

[edit] History

In the nineteenth century there were a lot of books and articles about the possible inhabitants of other planets. Many people believed that intelligent beings might live on the moon, Mars, and Venus; but since travel to other planets was not yet possible, but some people suggested ways to signal the extraterrestrials even before radio was discovered.

Karl Gauss suggested that a giant triangle and three squares, the Pythagoras, could be drawn on the Siberian tundra. The outlines of the shapes would have been ten-mile wide strips of pine forest, the interiors could be rye or wheat.

The Pythagorus.
The Pythagorus.

Joseph Johann Littrow proposed using the Sahara as a blackboard. Giant trenches several hundred yards wide could delineate twenty-mile wide shapes. Then the trenches would be filled with water, and then enough kerosene could be poured on top of the water to burn for six hours. Using this method, a different signal could be sent every night.

Meanwhile, other astronomers were looking for signs of life on other planets. In 1822, Franz von Gruithuisen thought he saw a giant city and evidence of agriculture on the moon, but astronomers using more powerful instruments refuted his claims. Gruithuisen also believed he saw evidence of life on Venus. "Ashen light" had been observed on Venus, and he postulated that it was caused by a great fire festival put on by the inhabitants to celebrate their new emperor. Later he revised his position, stating that the Venusians could be burning their rainforest to make more farmland.

By the late 1800s, the possibility of life on the moon was put to rest. Astronomers at that time believed in the Kant-Laplace hypothesis, which stated that the farthest planets from the sun are the oldest--therefore Mars was more likely to have advanced civilizations than Venus. It was evident that Venus was perpetually shrouded in clouds, so the Venusians probably wouldn't be very good astronomers. Subsequent investigations focused on contacting Martians. In 1877 Giovanni Schiaparelli announced he had discovered canals on Mars--this was followed by thirty years of Mars enthusiasm.

The inventor Charles Cros was convinced that pinpoints of light observed on Mars and Venus were the lights of large cities. He spent years of his life trying to get funding for a giant mirror to signal the Martians with. The mirror would be focused on the martian desert, where the intense reflected sunlight could be used to burn figures into the martian sand.

In 1899, the inventor Nikola Tesla "recorded" signals of what he believed were Extraterrestrial radio signals, but the scientific community rejected these announcements and his data. Tesla spent the latter part of his life trying to signal Mars.

Around 1900, The Guzman Prize was created; the first person to establish interplanetary communication would be awarded 100,000 francs under one stipulation: Mars was excluded because Madame Guzman thought communicating with Mars would be too easy to deserve a prize. [1]

When the Martian canals proved illusory, it seemed that man was alone in the solar system.

[edit] Mathematical and scientific languages

[edit] Astraglossa

Published in 1953 by Lancelot Hogben describes a system for combining numbers and operators in a series of short and long pulses. In Hogben's system, short pulses represent numbers, while trains of long pulses represent symbols for addition, subtraction, etc.

[edit] Lincos (Lingua cosmica)

Lincos: Design of a Language for Cosmic Intercourse, published in 1960 by Hans Freudenthal, expands upon Astraglossa to create a general-purpose language derived from basic math and logic symbols.

[edit] Carl Sagan

The science fiction novel Contact by Carl Sagan explored in some depth how a message might be constructed to allow communication with an alien civilization, using the prime numbers as a starting point, followed by various universal principles and facts of mathematics and science. Sagan also authored a non-fiction book on the subject.[2]

[edit] A language based on the fundamental facts of science

Published in 1992 by Carl Devito and Richard Oehrle, is similar in syntax to Astraglossa and Lincos but builds its vocabulary around known physical properties.

[edit] Pictorial messages

Pictorial communication systems seek to describe fundamental mathematical or physical concepts via simplified diagrams sent as bitmaps. These messages assume that the recipient has similar visual capabilities (weak assumption) and can understand basic math and geometry (strong assumption because both are prerequisites for building the optimal shape for a radio or optical telescope). A common critique of these systems is that they assume a shared understanding of special shapes, which may not be the case with a species with substantially different vision, and therefore a different way of interpreting visual information.

[edit] Pioneer probes

The two Pioneer plaques were launched on Pioneer 10 and Pioneer 11 in 1972 and 1973, depicting the location of the Earth in the galaxy and the solar system, and the form of the human body.

[edit] Voyager probes

Launched in 1977, the Voyager probes carried two golden records that were inscribed with diagrams depicting the human form, our solar system and its location. Also included were recordings of pictures and sounds from Earth.

[edit] The Arecibo message

The Arecibo message, transmitted in 1974, was a 1679 pixel image with 73 rows and 23 columns. It shows the numbers one through ten, the atomic numbers of hydrogen, carbon, nitrogen, oxygen, and phosphorus, the formulas for the sugars and bases in the nucleotides of DNA, the number of nucleotides in DNA, the double helix structure of DNA, a figure of a human being and its height, the population of Earth, our solar system, and an image of the Arecibo telescope with its diameter.

[edit] Cosmic Call messages

The Cosmic Call messages consisted of few digital sections - "Rosetta Stone", copy of Arecibo Message, Bilingual Image Glossary, the Braastad message, as well as text, audio, video and other image files submitted for transmission by everyday people around the world. The "Rosetta Stone" was composed by Stephane Dumas and Yvan Dutil and represents a multi-page bitmap that builds a vocabulary of symbols representing numbers and mathematical operations. The message proceeds from basic math to progressively more complex concepts, including physical processes and objects (such as a hydrogen atom). The message is designed with noise resistant format and characters, which make it resistant to alteration by noise. These Messages were transmitted in 1999 and 2003 from Evpatoria Planetary Radar under scientific guidance of Alexander Zaitsev. Richard Braastad coordinated the overall project.

[edit] Multi-modal messages

[edit] Teen-Age Message

The Teen-Age Message, composed by Russian scientists (Zaitsev, Gindilis, Pshenichner, Filippova) and teens, was transmitted from the 70-m dish of Evpatoria Deep Space Center to six Sun-like stars on August 29 and September 3 and 4, 2001. The message consists of three parts:

Section 1 represents coherent sounding radio signal with slow Doppler wavelength tuning to imitate transmission from Sun's center. This signal was transmitted in order to help Extraterrestrials detect the TAM and diagnose the radio propagation effect of interstellar medium.

Section 2 is analog information and represents musical melodies, performed on the Theremin. This electric musical instrument produces quasi-monochromatic signal, which is easily detectable across interstellar distances. There were seven musical compositions in the 1st Theremin Concert for Aliens.

Section 3 represents a well-known Arecibo-like binary digital information: Logotype of TAM, bilingual Russian and English Greeting to Aliens and Image Glossary.

[edit] Cosmic Call 2003 message

The Cosmic Call 2003 message contained text, images, video, music, the Dutil/Dumas message, a copy of the 1974 Arecibo message, BIG = Bilingual Image Glossary, the AI program Ella, and the Braastad message.

[edit] Algorithmic messages

Algorithmic communication systems are a relatively new field within CETI. In these systems, which build upon early work on mathematical languages, the sender describes a small set of math and logic symbols that form the basis for a rudimentary programming language that the recipient can run on a virtual machine. Algorithmic communication has a number of advantages over static pictorial and mathematical messages, including: localized communication (the recipient can probe and interact with the programs within a message, without transmitting a reply to the sender and then waiting years for a response), forward error correction (the message might contain algorithms that process data elsewhere in the message), and the ability to embed proxy agents within the message. In principle, a sophisticated program when run on a fast enough computing substrate, may exhibit complex behavior and perhaps intelligence.

[edit] CosmicOS

CosmicOS, designed by Paul Fitzpatrick at MIT, describes a virtual machine that is derived from lambda calculus.

[edit] Logic Gate Matrices

Logic Gate Matrices (aka LGM), developed by Brian McConnell, describes a universal virtual machine that is constructed by connecting coordinates in an n-dimensional space via math and logic operations, for example: (1,0,0) <-- (OR (0,0,1) (0,0,2)). Using this method, one can describe an arbitrarily complex computing substrate as well as the instructions to be executed on it.

[edit] CETI researchers

  • Frank Drake (SETI Institute) : SETI pioneer, composed the Arecibo message with Carl Sagan
  • Laurence Doyle (SETI Institute) : studies animal communication, and has developed statistical measures of complexity in animal utterances as well as human language.
  • Stephane Dumas : developed Cosmic Call messages, as well as a general technique for generating 2-D symbols that remain recognizable even if corrupted by noise.
  • Yvan Dutil : developed Cosmic Call messages with Stephane Dumas.
  • Paul Fitzpatrick (MIT) : developed CosmicOS system based on lambda calculus
  • Brian McConnell : developed framework for algorithmic communication systems (ACETI) from 2000-2002.
  • Marvin Minsky (MIT AI researcher) : first proposed the idea of including algorithms within an interstellar message.
  • Carl Sagan (deceased) : co-authored the Arecibo message, and was heavily involved in SETI throughout his life.
  • Douglas Vakoch (SETI Institute) : studies CETI and has published numerous articles, as well as an upcoming book from MIT Press about interstellar communication.
  • Alexander Zaitsev (IRE, Russia) : composed Teen Age Message with Boris Pshenichner, Lev Gindilis, Lilia Filippova, et al., composed Bilingual Image Glossary for Cosmic Call 2003 Message, Scientific Manager of transmitting from Evpatoria Planetary Radar the Cosmic Call 1999, the Teen Age Message 2001, and the Cosmic Call 2003.

[edit] See also

[edit] References

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