November 16 – Anniversary of a Message to E.T.s

nPostednon November 16, 2015

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nWhatndo you think? Is it a smart idea that humans beamed a message intonspace to a large cluster of stars—not knowing who or what, ifnanybody, would ever receive the message?

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nWhatnsort of aliens might intercept the message? Would they be able toninterpret it? Would they answer?

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nWhatnif they are mean and violent aliens, the sort who would love tondiscover a yummy, tender new species to gobble up—and a new planetnto plunder? Should we be announcing our presence?

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The Arecibo radio telescope

nOnnthis date in 1974, humans DID broadcast a complex message to the M13nstar cluster. Because it was sent by the Arecibo radio telescope innPuerto Rico, we call it the Arecibo message.

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nNow,ndon’t worry. The M13 cluster is about 25,000 light years away! So,neven if ExtraTerrestrial intelligences do receive the message (andnwhat are the chances that any E.T.s who live in the region would benpointing a radio telescope our way just at the right time?), it won’tnbe for 25,000 years! And if they tried to come visit us, theynwouldn’t arrive for tens of thousands of years after that! I thinknwe’re good.

The M13 cluster

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nNotnto mention, there are plenty of planets to plunder with nontechnological intelligences to fight off, so it’s not likely annM13-E.T. would be interested in our little, faraway Earth …Also, wenhumans would probably be completely inedible to creatures who evolvednon another planet. Again, I think we’re good!

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nSo…whyndid we send the message?

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nIfnthe possible alien intelligences living on planets in the M13 starncluster are too far away to chat with…and if it is unlikely in thenextreme, even, that any of them will receive our one-timenbroadcast…why did we send it?

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nThenArecibo message was a demonstration of the capabilities of the radiontelescope. Also, it was an important thought experiment of what tonlook for when we search for messages from intelligent aliens. How cannwe communicate with creatures who don’t speak any of our Earthnlanguages, and who may not “speak” at all, with sounds, sincenthey evolved 100% separately from all forms of Earth life?

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nThenthing about any aliens who would be intelligent enough and advancednenough to receive a radio message, they would share something verynimportant with humans – their science would be based on the samenuniversal laws and facts as ours. In a way, we would share a languagenwith every technological alien in the universe: the language ofnscience.

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nChecknit out: The scientists who created the message, Dr. Frank Drake andnCarl Sagan (who also earned a PhD but is generally referred tonwithout the “Dr.” title), chose to code a message as 1,679 binaryndigits. “Binary digits” are zeroes and ones, which are useful inncommunicating with aliens because zeroes and ones can represent offnand on, or black and white. If you arrange the off/on black/whitenbits into a rectangular grid, you can create a picture. As a matternof fact, we humans do this all the time with our computer graphics!nEven the text on our screens is created by streams of binary digitsnthat code for pixels…

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nSo,nhow would the aliens know what size of rectangular grid to create tonsee the picture we were trying to send? That’s where the number 1,679ncomes in…

You see, that number is semi-prime. That meansnthat, if you multiply the two prime numbers 73 and 23, you get 1,679.nSince prime numbers are prime in any base number system, aliens willnbe able to figure out that they could arrange the on/off pixels inneither a grid that is 73 rows by 23 columns or one that is 23 rows byn73 columns. The latter grid produces a jumble, but the 73 rows by 23ncolumns arrangement produces a picture:

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nNoten– the colors were added to help us talk about the various parts ofnthe message. There is no color information in the original message!

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nThentop shapes, in white, are a number system that is will be used in thenmessage, showing the numbers 1 through 10.

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nThennext shape, which is purple, includes the atomic numbers of thenelements hydrogen, carbon, nitrogen, oxygen, and phosphorus. Thesenare the elements that make up DNA.

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nThengreen shapes are the formulas for sugars and bases in the nucleotidesnof DNA.

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nThenlong white strip in the middle is the number of nucleotides in DNA.

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nThenblue wavy lines are a picture intended to show the double helixnstructure of DNA.

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nThenred portion is a picture of a human. I wish our heads—and thereforenour brains—looked just a bit bigger!

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nThenwhite bit in the middle of the blue line, to the left of the human,nis an indication of the average height of a grown man.

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nThenwhite bit to the right of the human is the approximate number ofnhumans on Earth.

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nThenyellow shapes are a rough picture of the solar system, with a largensun, four small inner planets, two enormous and two medium-sized gasngiant planets, and a small outer planet. The planet the message isncoming from is indicated by the fact that it is raised up above thenothers.

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nThenlower purple shape is an outline of the radio telescope.

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nThenwhite bits in the middle of the blue line, below the radio telescope,nis the size of the radio telescope’s dish.

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nQuestions?

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nIfnyou want to read more about the Arecibo message, check out this Wikipedia article.

nDidnyou know…?

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nYouncan buy t-shirts with the whole Arecibo message imprinted on it…ornjust the self-portrait from the message!