Arecibo message
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The Arecibo message was beamed into space a single time (not repeated) via frequency modulated radio waves at a ceremony to mark the remodeling of the Arecibo radio telescope on 16 November 1974.[1] It was aimed at the globular star cluster M13 some 25,000 light years away because M13 was a large and close collection of stars that was available in the sky at the time and place of the ceremony.[2] The message consisted of 1679 binary digits, approximately 210 bytes, transmitted at a frequency of 2380 MHz and modulated by shifting the frequency by 10 Hz, with a power of 1000kW. The transmission rate of the message was one bit per second, thus the entire transmission lasted 1679 seconds.[3][1]
The cardinality of 1679 was chosen because it is a semiprime (the product of two prime numbers), to be arranged rectangularly as 73 rows by 23 columns. The alternate arrangement, 23 rows by 73 columns, produces jumbled nonsense. The message forms the image shown on the right, or its inverse, when translated into graphics characters and spaces.[4]
Dr. Frank Drake, then at Cornell University and creator of the famous Drake equation, wrote the message, with help from Carl Sagan, among others.[1] The message consists of seven parts that encode the following:[4]
- The numbers one (1) through ten (10)
- The atomic numbers of the elements hydrogen, carbon, nitrogen, oxygen, and phosphorus, which make up deoxyribonucleic acid (DNA)
- The formulas for the sugars and bases in the nucleotides of DNA
- The number of nucleotides in DNA, and a graphic of the double helix structure of DNA
- A graphic figure of a human, the dimension (physical height) of an average man, and the human population of Earth
- A graphic of Earth's Solar System
- A graphic of the Arecibo radio telescope and the dimension (the physical diameter) of the transmitting antenna dish
Because it will take 25,000 years for the message to reach its intended destination of stars (and an additional 25,000 years for any reply), the Arecibo message was more a demonstration of human technological achievement than a real attempt to enter into a conversation with extraterrestrials. In fact, the stars that the message was aimed at will no longer be there when it arrives.[1] According to the Cornell News press release of November 12, 1999, the real purpose of the message was not to make contact, but to demonstrate the capabilities of newly installed equipment.[1]
Contents |
[edit] Explanation
[edit] Numbers
1 2 3 4 5 6 7 8 9 10 ---------------------- 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 <-least-significant-digit marker
The numbers from 1 to 10 appear in binary format (the bottom row marks the beginning of each number).
Even assuming that recipients know the purpose of this section is to write decimal in binary, the encoding of the numbers may not be immediately obvious due to the way they have been written. To read the first seven digits, ignore the bottom row, and read them as three binary digits from top to bottom, with the top digit being the most significant.
The readings for 8, 9 and 10 are a little different, as they have been given an additional column next to the first (to the right in the image). This is probably intended to show that numbers too large to fit in a column can be written in several contiguous ones, where the contiguous columns do not have the base marker.
[edit] DNA elements
H C N O P 1 6 7 8 15 ---------- 0 0 0 1 1 0 1 1 0 1 0 1 1 0 1 1 0 1 0 1 X X X X X
The numbers 1, 6, 7, 8 and 15 appear. These are the atomic numbers of hydrogen (H), carbon (C), nitrogen (N), oxygen (O), and phosphorus (P), the components of DNA.
The numbers 8 and 15 are written in a logical extension of binary encoding, rather than with the contiguous-columns method shown in the message's number figures at the top:
[edit] Nucleotides
Deoxyribose Adenine Thymine Deoxyribose (C5OH7) (C5H4N5) (C5H5N2O2) (C5OH7)
Phosphate Phosphate (PO4) (PO4)
Deoxyribose Cytosine Guanine Deoxyribose (C5OH7) (C4H4N3O) (C5H4N5O) (C5OH7)
Phosphate Phosphate (PO4) (PO4)
The nucleotides are described as sequences of the five atoms that appear on the preceding line. Each sequence represents the molecular formula of the nucleotide as incorporated into DNA (as opposed to the free form of the nucleotide).
For example, deoxyribose (C5OH7 in DNA, C5O4H10 when free), the nucleotide in the top left in the image, is read as:
11000 10000 11010 XXXXX ----- 75010
i.e. 7 atoms of hydrogen, 5 atoms of carbon, 0 atoms of nitrogen, 1 atom of oxygen, and 0 atoms of phosphorus.
[edit] Double helix
11 11 11 11 11 01 11 11 01 11 01 11 10 11 11 01 X
1111111111110111 1111101101011110 (binary) = 4,294,441,822 (decimal)
DNA double helix (the vertical bar represents the number of nucleotides, but the value depicted is around 4.3 billion when in fact there are about 3.2 billion base pairs in the human genome).
[edit] Humanity
X011011
111111
X0111 110111
111011
111111
110000
1110 (binary) = 14 (decimal)
000011 111111 110111 111011 111111 110110 (binary) = 4,292,853,750 (decimal)
The element in the center represents a human. The element on the left (in the image) indicates the average height of a person: 1764 mm. This corresponds to the horizontally written binary 14 multiplied by the wavelength of the message (126 mm). The element on the right depicts the size of human population in 1974, around 4.3 billion. In this case, the number is oriented horizontally rather than vertically, with the least-significant-digit marker to the upper left in the image.
[edit] Planets
Earth
Sun Mercury Venus Mars Jupiter Saturn Uranus Neptune Pluto
The solar system, showing the Sun and the planets in the order of their position from the Sun: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto. (Pluto has since been reclassified as a dwarf planet by the International Astronomical Union, but it was still considered a planet at the time the message was transmitted.)
The Earth is the third planet from the Sun - its graphic is shifted up to identify it as the planet from which the signal was sent. The human figure is shown "standing on" the Earth graphic.
In addition to showing position, the graphic provides a general, not-to-scale size reference of each planet and the Sun.
[edit] Telescope
bottom two rows:
100101
<--- 111110X --->
100101 111110 (binary) = 2,430 (decimal)
The last part represents the Arecibo radio telescope with its diameter (2430 multiplied by the wavelength gives 306.18 m). In this case, the number is oriented horizontally, with the least-significant-digit marker to the lower right in the image.
[edit] Message as binary string[4]
0000001010101000000000000101000001010000000100100010001000100101100101010 1010101010100100100000000000000000000000000000000000001100000000000000000 0011010000000000000000000110100000000000000000010101000000000000000000111 1100000000000000000000000000000000110000111000110000110001000000000000011 0010000110100011000110000110101111101111101111101111100000000000000000000 0000001000000000000000001000000000000000000000000000010000000000000000011 1111000000000000011111000000000000000000000001100001100001110001100010000 0001000000000100001101000011000111001101011111011111011111011111000000000 0000000000000000010000001100000000010000000000011000000000000000100000110 0000000001111110000011000000111110000000000110000000000000100000000100000 0001000001000000110000000100000001100001100000010000000000110001000011000 0000000000001100110000000000000110001000011000000000110000110000001000000 0100000010000000010000010000000110000000010001000000001100000000100010000 0000010000000100000100000001000000010000000100000000000011000000000110000 0000110000000001000111010110000000000010000000100000000000000100000111110 0000000000010000101110100101101100000010011100100111111101110000111000001 1011100000000010100000111011001000000101000001111110010000001010000011000 0001000001101100000000000000000000000000000000000111000001000000000000001 1101010001010101010100111000000000101010100000000000000001010000000000000 0111110000000000000000111111111000000000000111000000011100000000011000000 0000011000000011010000000001011000001100110000000110011000010001010000010 1000100001000100100010010001000000001000101000100000000000010000100001000 0000000001000000000100000000000000100101000000000001111001111101001111000
or
00000010101010000000000 00101000001010000000100 10001000100010010110010 10101010101010100100100 00000000000000000000000 00000000000011000000000 00000000001101000000000 00000000001101000000000 00000000010101000000000 00000000011111000000000 00000000000000000000000 11000011100011000011000 10000000000000110010000 11010001100011000011010 11111011111011111011111 00000000000000000000000 00010000000000000000010 00000000000000000000000 00001000000000000000001 11111000000000000011111 00000000000000000000000 11000011000011100011000 10000000100000000010000 11010000110001110011010 11111011111011111011111 00000000000000000000000 00010000001100000000010 00000000001100000000000 00001000001100000000001 11111000001100000011111 00000000001100000000000 00100000000100000000100 00010000001100000001000 00001100001100000010000 00000011000100001100000 00000000001100110000000 00000011000100001100000 00001100001100000010000 00010000001000000001000 00100000001100000000100 01000000001100000000100 01000000000100000001000 00100000001000000010000 00010000000000001100000 00001100000000110000000 00100011101011000000000 00100000001000000000000 00100000111110000000000 00100001011101001011011 00000010011100100111111 10111000011100000110111 00000000010100000111011 00100000010100000111111 00100000010100000110000 00100000110110000000000 00000000000000000000000 00111000001000000000000 00111010100010101010101 00111000000000101010100 00000000000000101000000 00000000111110000000000 00000011111111100000000 00001110000000111000000 00011000000000001100000 00110100000000010110000 01100110000000110011000 01000101000001010001000 01000100100010010001000 00000100010100010000000 00000100001000010000000 00000100000000010000000 00000001001010000000000 01111001111101001111000
[edit] See also
[edit] References
- ^ a b c d e "Cornell News: It's the 25th anniversary of Earth's first (and only) attempt to phone E.T., FOR RELEASE: Nov. 12, 1999". http://www.news.cornell.edu/releases/Nov99/Arecibo.message.ws.html. Retrieved on 2008-03-29.
- ^ "Larry Klaes. Ithaca Times - Making Contact". http://www.zwire.com/site/news.cfm?newsid=15663534. Retrieved on 2007-07-27.
- ^ Jay M. Pasachoff. "Chapter 20: Life in the Universe". Astronomy: From the Earth to the Universe, Updates by Chapter, 5th Ed.. http://www.williams.edu/Astronomy/jay/ETU5/chapter20_5th.html. Retrieved on 2007-05-05.
- ^ a b c Cassiday, George. "The Arecibo Message". http://www.physics.utah.edu/~cassiday/p1080/lec06.html. Retrieved on 2007-07-27.
