Published on September 23, 2007
Communication with Extra Terrestrial Intelligence (CETI) Un-Distinguished Lecture Series Immad Naseer May 11th, 2007
SETI • Searching for and analyzing signals that could have been sent by aliens. • Proactively sending out signals into space in the hope that they will be picked up by an intelligent life form.
Received signals • In spite a lot of searching, SETI hasn’t met with any real success thus far. • The only exception was a strong narrowband radio signal detected by the Big Ear telescope of Ohio State university on August 15, 1977 • The signal lasted for 72 seconds, and wasn’t detected again in spite of a lot of searching
The WOW! signal The circled code 6EQUJ5 describes the intensity variation of the signal
Why haven’t we been contacted? • There might be no “intelligent” life out there. • They are still trying to contact us, waiting for their signals to be picked by us. • They may be way more advanced than us, and waiting for us to “grow up” before we join the cosmic society.
Sent messages • Arecibo message • Pioneer plaque • Voyager record • Encounter 2001 message • Encounter 2003 message
Arecibo message • A radio message beamed towards the globular star cluster M13 (distance: 25,000 light years) in 1974, from the Arecibo radio telescope • Created by Dr. Frank Drake and Carl Sagan • The message consisted of 1679 binary digits. 1679 = 73 * 23 (a semi prime)
Pioneer plaque • A pair of aluminums plaques placed on the Pioneer 10 & 11 spacecraft, feature a pictorial message from humanity. • The pioneer spacecrafts were the first human-built objects to leave the solar system. • The mean time for the spacecraft to come within 30 astronomical units of a star is longer than the current age of our galaxy.
Voyager golden record • A phonograph record included in the two Voyager spacecrafts launched in 1977 containing sounds and images of earth. • The cover of the record contained symbolic instructions on how to play the record.
“Communicating” with ET • Communicating anything “non-trivial” will require some sort of language. • Since they will probably not share a language with us, we will have to invent a new language for communicating with them.
Lincos – Lingua Cosmica • An artificial language for cosmic communication designed by Dr. Hans Freudanthal in 1960. • It was designed to be capable of encapsulating the whole bulk of our language. Part II of the book was promised in Part I, but never came out.
Lincos The book is divided into four sections. Mathematics Time Behavior Space, mass and motion The book follows the policy of introduction by description rather than definition.
Lincos – Mathematics > | < | = | + | - | <> | <= | => | . | . . | . . . | . . . . . . . | 1 | 10 | 11 | 111 | a | b | c | -> | ? | / | / | <-> Lincos words are presented without any context, to stress their individuality.
Lincos – Mathematics .....>... ...<..... ....=.... ....+..=...... Illustrating basic mathematical operations through ostensive numerals.
Lincos – Mathematics .=1 . . = 10 . . . = 11 . . . . = 100 Ostensive numerals replaced by algorithmic ones.
Lincos – Mathematics 100 > 10 100 + 11 > 10 + 11 100 + 1 > 10 + 1 100 + 110 > 10 + 110 100 + a > 10 + a Introduction to a variable.
Lincos – Mathematics a > 100 => a > 10 (punctuation removed) a < 111 => a< 1110 a + b = c => a = c – b a + b = c => b = c – a a = c – b => a + b = c
Lincos – Mathematics ?x . x + 10 = 111 x + 10 = 111 => x = 101 ?x . a< b ^ x + a = b a < b ^ x + a = b => x = b – a Questions and answers are introduced.
Lincos – Mathematics 1/11 = 0,01010101 Etc. 1/101 =0,0011001100110011 Etc. a0 = 1 a1 = aa0 = a a10 = aa1 = aa a11 = aa10 = aaa Etc. Introduction to “etc”
Lincos – Mathematics The book goes on to introduce propositional logic, set theory, and first-order logic.
Lincos – Time Similar to the introduction of numbers, time- signals are introduced as ostensive, ideophonetic signs. Dur ------ = Sec A
Lincos – Time Ecc ___ ----- V x.y. Fre x = A ^ Fre y = B ^ x Ant y x Ant y y Pst x The concept of ‘before’ and ‘after’
Lincos – Time After some time, a clock is installed on a particular frequency. It ticks per second through all Lincos programs onwards. The receiver is instructed on how to read the clock.
Lincos – Time Arbitrary “events” are introduced by a wild complex of radio signals. P t2 . (event) t1 T1 Usq T2 Fit P (report on event)
Lincos – Behavior • Behavior requires the presence of actors. Actors Ha, Hb and Hc are introduced, and the distinctness of each actor is stressed. • Since mathematics is the only subject we know till now, the actors start conversing about mathematics.
Lincos – Behavior Ha Inq Hb ?x. 10x = 101 Hb Inq Ha 101/10 Ha Inq Hb Ben (good) Conversations require the concept of good (Ben) and bad (Mal), in addition to true (Ver) and false (Fal)
Lincos – Behavior Ha Inq Hb ?x 100x = 1010 Hb Inq Ha 1010/100 Ha Inq Hb Mal Hb Inq Ha 1/10 Ha Inq Hb Mal Hb Inq Ha 101/10 Ha Inq Hb Ben
Lincos – Behavior Ha Inq Hb ?x. x10 = 11001 Hb Inq Ha 101x101 = 11001 Ha Inq Hb Mal Hb Inq Ha 101x101 = 11001 ∈Ver Ha Inq Hb Ver Tan Mal . x10 = 11001 => x=101 Hb Inq Ha 101 ∨ -101 Ha Inq Ha Ben True but Bad
Lincos – Behavior Ha Inq Hb ?x 10x10 = x Hb Inq Ha 10x10=10 Ha Inq Hb Mal Ha Inq Hc ?x 10x10 = x Hc Inq Ha 10x10 = 100 Ha Inq Hc Ben Hc >IQ Hb Hc has greater IQ than Hb
Lincos – Behavior • The book goes on to give more complex examples of behavior such as – Honest quoting – Animals cannot speak – Understanding as recognizing what another person said. – Polite speech – Games. Minimax principle etc.
Lincos – Space, motion and mass • So far, the actors Ha, Hb and Hc were ghosts. • Distance of place recognized by delay of signals. • Three dimensional space, volume introduced. • Movement. • Kepler’s laws of motion. Relativity etc.
Encounter 2001 & 2003 messages • Among other information, contained messages inspired from the Lincos language. • In addition to words, contains crude pictures of the solar system, mountains, male and female humans, DNA, continents etc. • Physics, chemistry and astronomy are described, but complicated human behavior is not shown.
Algorithmic languages • An algorithm can speak a thousand words! • Instead of introducing game-centric behavior of humans, why not build a game for them that they can play themselves?
CosmicOS • Inspired by Lincos, but instead of a language for conversation, introduces a programming language based on lambda calculus. • After the introduction of the basics, introduces the semantics of the Java bytecodes. • Finally, a game is described using Java’s bytecodes. The game’s logic is fully described though it is not rendered anywhere.
CosmicOS The message as a single image
Conclusion • Perhaps there should be some “understandability” studies for some of these languages. • Apart from ET, they can also be used as input for some machine learning algorithms, particularly CosmicOS. • For those interested, there are several artificially constructed messages available on the internet to decode.
References • Interstellar communication, http://www.matessa.org/~mike/inter-comm.html • Arecibo message, http://en.wikipedia.org/wiki/Arecibo_message • Pioneer plaques, http://en.wikipedia.org/wiki/Pioneer_plaque • Voyager record, http://en.wikipedia.org/wiki/Voyager_Golden_Record • Encounter 2001 message, http://www.matessa.org/~mike/2001.html • Encounter 2003 message, http://web.archive.org/web/20030705140835/teamencounter.com/missions/message.asp • LINCOS: Design of a Language for Cosmic Intercourse. Hans Freudenthal. North-Holland Publishing Company, Amsterdam, 1960. • Lincos, http://www.matessa.org/~mike/lincos.html • CosmicOS, http://cosmicos.sourceforge.net/