Arecibo message
The Arecibo message is a message from Earth to possible extraterrestrials in the form of a radio wave signal. It was broadcast once on November 16, 1974 at 1 a.m. AST ( Atlantic Standard Time ) from the Arecibo Observatory , the world's second largest radio telescope near Arecibo , Puerto Rico . The main author of the message is the astronomer and astrophysicist Frank Drake .
Target point of the signal
The possible destinations of the signal were limited by the radio telescope used. Its orientation cannot be changed, so that the target region has to “walk through” the radiation area of the telescope.
The target of the signal is the globular cluster M13 in the constellation Hercules . This is about 25,000 light years from Earth and consists of more than 300,000 individual stars. It could be reached with the telescope and was chosen because many stars are gathered here in a relatively small space. Because of this, a higher chance of encountering an inhabited world was seen here .
The signal
content
The message contains binary coded information about human biology as well as about the human population and the origin of the signal. In the adjacent graphics, the zeros and ones transmitted with the signal are grouped in color to show the related objects. This color information is not available to a potential recipient.
Coding
The message consists of a total of 1679 bits . A receiver would have to decompose this number into its prime factors 23 and 73 and then arrange the sequence of bits in a (width × height) 23 × 73 matrix as pixels of a black and white image . In order to recognize the objects contained in the message, a recipient would then have to identify empty lines as paragraphs and empty columns as lateral separations of neighboring objects.
The arrangement here is in the write-read direction from left to right and line by line downwards. The direction of writing to the left is equivalent, while a line sequence upwards would represent the figure of the person - on the vertically erect picture - falling, upside down.
The arrangement in a 73 × 23 matrix, which is also possible, does not make a meaningful representation.
The first paragraph - numbers
The first part of the message, shown in white in the graphic, shows ten objects that represent the numbers 1 to 10 in binary coding . A colored square represents a one, a black square represents a zero. The bottom line does not count towards the binary coding, but indicates the position of the least significant bit. The ten objects are laterally separated by empty columns. The first part is to be interpreted as follows:
0 0 0 1 1 1 1 00 00 00 0 1 1 0 0 1 1 00 00 10 1 0 1 0 1 0 1 01 11 01 X X X X X X X X X X ← markiert die Informationseinheit mit der kleinsten Wertigkeit
To be read - from left to right - the binary codes (decimal codes in brackets) 001 (1) , 010 (2) , 011 (3) , 100 (4) , 101 (5) , 110 (6) , 111 (7) , 001000 (8) , 001001 (9) , 001010 (10) .
In order to understand the meaning of this paragraph, a recipient would have to decode it as a binary code and would have the reading instructions to read binary numbers from a base point.
The second paragraph - chemical elements
The second part of the message, colored purple in the graphic opposite, is a reading guide for the third part of the message that follows it.
It consists of an object that measures 5 × 5 fields. According to the reading instructions in the first section, the five columns result in the sequence of numbers "1 6 7 8 15" from left to right. These are to be decoded as the atomic numbers or proton numbers of the chemical elements hydrogen , carbon , nitrogen , oxygen and phosphorus . All five substances are important elements of biochemistry and are the elements that make up DNA .
The third paragraph - nucleotides
According to the previous reading instructions, the third part - colored green in the graphic opposite - results in four nucleotides , the building blocks of human DNA . Each of the twelve objects indicates the number of elements it contains from left to right. The first column shows the number of hydrogen atoms contained (atomic number 1), the second the number of carbon atoms (atomic number 6) etc.
The twelve objects thus represent the following substances:
| Deoxyribose (C 5 OH 7 ) | Adenine (C 5 H 4 N 5 ) 1 | Thymine (C 5 H 5 N 2 O 2 ) 1 | Deoxyribose (C 5 OH 7 ) |
| Phosphate (PO 4 ) | Phosphate (PO 4 ) | ||
| Deoxyribose (C 5 OH 7 ) | Cytosine (C 4 H 4 N 3 O) 1 | Guanine (C 5 H 4 N 5 O) 1 | Deoxyribose (C 5 OH 7 ) |
| Phosphate (PO 4 ) | Phosphate (PO 4 ) |
In the form shown, the twelve objects build two rungs of DNA . The four heterocyclic nucleobases adenine, thymine, guanine and cytosine in the middle form the crossbars of the ladder and the objects on the sides form the DN backbone. This part of the message informs a recipient of the structure of the DNS.
The fourth paragraph - structure of the DNS
The two-column stripe in the middle of the fourth part of the message, colored white in the graphic opposite, represents the number 4,294,441,822. This is supposed to represent the approximate number of nucleotides in the human genome , which is only about 3,000,000,000.
The double helix surrounding the stripe, which is colored blue in the figure, shows the spatial structure of the DNA , the double helix in side view.
The fifth paragraph - humanity
After information about biochemistry including that of humans has been coded in the first four parts of the message , the fifth part deals with human anatomy and humanity with a total of three objects .
The first object, colored blue and white in the graphic, shows the size of the person. The part colored white shows the number 14 (binary 1110, read from right to left in the graphic) in the middle of a vertical bar as a dimension line. The vertical bar, colored blue in the graphic, indicates that this is a dimension for the size of the human figure next to it. The height is calculated from the number 14 multiplied by the wavelength of the message, 12.6 cm. The result is 176.4 cm, the approximate height of a person.
The middle, red-colored object shows the rough sketch of the human figure. Thus, with the first two objects it is coded that the human is a bipedal 1.76 meters high. The stick figure's head is surrounded by the double helix of the fourth paragraph for reference.
The right object shows the number 4,292,853,750 (binary 11111111110111111011111111110110, read from right to left and from bottom to top in the graphic), the approximate number of the world's population at the time the message was sent (1974).
The sixth paragraph - planet earth
The sixth part of the message, colored yellow in the graphic opposite, represents our solar system and the position of planet earth in it.
The size of the objects represents the approximate proportions of the celestial bodies. The sun is a total of 3 × 3, i.e. nine fields, the fifth and sixth planets, the gas giants Jupiter and Saturn , are three fields each, Uranus and Neptune are two fields and all other planets ( Mercury , Venus , Earth , Mars and Pluto , which was still officially a planet at the time of the Arecibo message) one field each.
To mark the home planet of mankind, the object representing the earth is located directly below the stick figure of the fifth paragraph and is shifted up one space.
The seventh paragraph - telescope or transmitter
The seventh and last part shows information about the transmitting observatory, the Arecibo observatory . Exactly below the earth of the sixth part of the message, there is a sketch of the observatory, colored purple in the graphic. What can be seen - centered with the earth and turned away from it - the spherical mirror and the beam path of the electromagnetic waves emitted from the focal point.
The part colored white shows the binary coded number 2430 (binary 100101111110, read from left to right and from top to bottom in the graphic) in the middle of a horizontal bar. This bar - colored blue in the graphic - indicates that it is a matter of width. The width is calculated from the number 2430 shown multiplied by the wavelength of the message, 12.6 cm. The result is approximately 306 m, the approximate diameter of the antenna (actually 304.8 m). The dimension line here has the same principle as the one that stands on humans: With a distance of one pixel from the dimension number, it consists of two terminal parts, each 4 pixels long.
technology
The signal was transmitted with a transmission power of 1 MW on a carrier frequency of 2.388 GHz (gigahertz), corresponding to a wavelength of 12.6 cm. The data bits of the message are transmitted one after the other on the carrier frequency by means of binary frequency shift keying (FSK) and a frequency deviation of 75 Hz. The data transmission by means of binary frequency shift keying corresponds to the procedure that was also common in the 1970s and early 1980s with acoustic couplers over telephone lines with frequencies adapted to the telephone system.
The base frequency of exactly 2.388 GHz was chosen to ensure good transmission conditions. The ideal frequency range for interstellar radio transmission is between 1 GHz and 10 GHz. Higher frequencies are absorbed by the water vapor in the atmosphere of a planet, lower frequencies would be drowned out in the noisy background of radio emissions from our galaxy.
The data transmission rate chosen was 10 bit / s. This transmission rate was chosen to be low in order to keep transmission errors to a minimum, but on the other hand not too low in order not to make the entire transmission of the message at the ceremonial opening of the observatory too long for the guests. Since the entire message has a length of 1679 bits, the one-time transmission took exactly 167.9 seconds, i.e. about 2 minutes and 48 seconds.
Messier 13 was chosen because a lot of stars are concentrated there in very dense space. However, it must be assumed that globular clusters are unlikely candidates for the evolution of life because they largely lack the heavy elements that are unique to Population I stars . Because of the great distance to Messier 13, very large receiving antennas with effective areas of at least a few 10 km² are required.
Target accuracy requirements
If, in almost 25,000 years, the message would have reached the globular cluster M13, it will be many light years away from the destination calculated at the time, as the self-rotation of the Milky Way was insufficiently taken into account before it was sent.
Requirements for interpretability
Critics find the message too difficult to understand as it takes a lot of mathematical tricks to decode the message . Imagine if a comparable message had come to earth 150 years ago - it could not have been received or understood.
requirements
A decryption of the message requires, among other things, the following conditions:
Complete reception
In order to decipher the content, the recipient must absolutely receive the transmission in full, i.e. from the first bit. If only a few bits are missing at the beginning of the received transmission, the whole thing cannot be deciphered. However, it is extremely unlikely that a receiver was set to this frequency by pure chance.
To increase your chances, you would have had to repeat the show often, preferably for several days.
Rectangular shape
The recipient has to interpret the contained prime numbers as length and width information of a rectangle. Should he not know any rectangles, but z. B. not deviate from the honeycomb shape common in the insect kingdom, no information needs to be decoded. A prerequisite for decryption is that the recipient has our level of knowledge in algebra and geometry .
The number 1679 can only be broken down into the prime factors 23 and 73 - in every number system. The rectangle as a basic shape in two dimensions and the right angle due to the property of orthogonality are obvious with a fundamental understanding of the geometry. The orientation of the rectangle alone is not a matter of course. From the possible arrangements, horizontal or vertical rectangle, the right one would have to be deduced.
Representation as a binary image
Once the rectangle is recognized, the binary number system must be used to read the encrypted information. Now the receiver has to display the signal or the rectangle optically and recognize the objects it contains .
Test of interpretability
After the message was drafted, Frank Drake presented it to his colleague Carl Sagan , who deciphered the message almost completely. Allegedly, the message was presented to other people, of whom those scientists who are active in the field could have correctly interpreted the message in many parts. There are no reliable sources for these tests.
Fundamental criticism of messages of this kind
Several scientists criticized the message for the ability to alert hostile aliens to humanity who might invade Earth to plunder its resources and subjugate or annihilate humanity. The astronomer Martin Ryle therefore lodged a complaint with the IAU and demanded that all further messages be omitted. The evolutionary biologist Jared Diamond compared the message in his book The Third Chimpanzee with the "suicidal folly of the last Inca ruler Atahualpa , who described the wealth of his capital to the gold-greedy Spaniards who captured him and gave them guides for the journey there." The astrophysicist, too Stephen Hawking expressed this view and referred to the discovery of America by Christopher Columbus , which had not turned out positive for the Native Americans.
In 2018, Michael Hippke from the Sonneberg Observatory and John G. Learned from the University of Hawaii warned that longer messages from aliens could contain malware or even hostile artificial intelligence . The authors assume that a longer message would have to be processed by IT systems which are susceptible to the malware it contains.
More extraterrestrial communication
- The Pioneer badge was installed on the Pioneer 10 and Pioneer 11 space probes (launched on March 3, 1972 and April 6, 1973, respectively) . It graphically contains basic information about our solar system.
- The space probes Voyager 1 and Voyager 2 (launched on September 5 and August 20, 1977 respectively) carry the Voyager Golden Record . It also contains engraved graphics and it also contains analogue coded audio and video recordings.
Other interstellar message projects were: Cosmic Call 1999 & 2003 , Teen Age Message 2001 , A Message From Earth 2008 and others.
See also
literature
- Frank Drake, Dava Sobel: Signals from other worlds. Searching for alien intelligences with the NASA SETI project. Bettendorf, Essen u. a. 1994, ISBN 3-88498-065-3 .
- The Staff at the National Astronomy and Ionosphere Center: The Arecibo message of November, 1974. In: Icarus , Vol. 26, No. 4, December 1975, pp. 462-466, doi: 10.1016 / 0019-1035 (75) 90116- 5
Web links
- naic.edu/ - Arecibo Observatory website
- Signals.de - Private website with detailed information on reading the message
- GoogleWatchBlog.de - Information about the Google Doodle version of the Arecibo message from 2018
Individual evidence
- ^ It's the 25th anniversary of Earth's first attempt to phone ET In: Cornell Chronicle . ( cornell.edu [accessed November 16, 2018]).
- ^ "Ryle brought a formal complaint to the International Astronomical Union. He asked the union to halt all further attempts by astronomers to contact other civilizations because of the possible harmful consequences to the human race. Ryle worried that terrestrial contact with intelligent aliens might lead to invade the Earth with the intention of colonizing us or stealing our mineral resources. " In: George Basalla: Civilized life in the universe - scientists on intelligent extraterrestrials. Oxford University Press, New York 2006, ISBN 0-19-517181-0 , p. 123.
- ↑ Should Mankind Hide? In: New York Times , November 22, 1976. bibcode : 1980qel..book..269. .
- ↑ Jared Diamond: The Third Chimpanzee: Evolution and Future of Man . From the American by Volker Englich. 3. Edition. Fischer Taschenbuch Verlag, Frankfurt am Main 2007, ISBN 978-3-596-17215-3 , pp. 275-276.
- ^ Stephen Hawking warns over making contact with aliens. In: BBC News. April 10, 2010, accessed November 16, 2014 .
- ↑ Michael Hippke, John G. Learned: Interstellar communication. IX. Message decontamination is impossible . 2018 arxiv : 1802.02180
- ↑ Alexander L. Zaitsev, Sergey P. Ignatov: Broadcast for Extra-Terrestrial Intelligence from Evpatoria Deep Space Center. Report on Cosmic Call 1999. November 30, 2002, accessed March 14, 2013 .
- ↑ Alexander L. Zaitsev: A Teen-Age Message to the Stars. December 28, 2002, accessed March 14, 2013 .
- ↑ Is anybody listening out there? BBC , October 9, 2008, accessed March 14, 2013 .
