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

Posted on November 16, 2015

What do you think? Is it a smart idea that humans beamed a message into space to a large cluster of stars—not knowing who or what, if anybody, would ever receive the message?

What sort of aliens might intercept the message? Would they be able to interpret it? Would they answer?

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

The Arecibo radio telescope
On this date in 1974, humans DID broadcast a complex message to the M13 star cluster. Because it was sent by the Arecibo radio telescope in Puerto Rico, we call it the Arecibo message.

Now, don't worry. The M13 cluster is about 25,000 light years away! So, even if ExtraTerrestrial intelligences do receive the message (and what are the chances that any E.T.s who live in the region would be pointing a radio telescope our way just at the right time?), it won't be for 25,000 years! And if they tried to come visit us, they wouldn't arrive for tens of thousands of years after that! I think we're good.

The M13 cluster

Not to mention, there are plenty of planets to plunder with no technological intelligences to fight off, so it's not likely an M13-E.T. would be interested in our little, faraway Earth ...Also, we humans would probably be completely inedible to creatures who evolved on another planet. Again, I think we're good!

So...why did we send the message?

If the possible alien intelligences living on planets in the M13 star cluster are too far away to chat with...and if it is unlikely in the extreme, even, that any of them will receive our one-time broadcast...why did we send it?

The Arecibo message was a demonstration of the capabilities of the radio telescope. Also, it was an important thought experiment of what to look for when we search for messages from intelligent aliens. How can we communicate with creatures who don't speak any of our Earth languages, and who may not “speak” at all, with sounds, since they evolved 100% separately from all forms of Earth life?

The thing about any aliens who would be intelligent enough and advanced enough to receive a radio message, they would share something very important with humans – their science would be based on the same universal laws and facts as ours. In a way, we would share a language with every technological alien in the universe: the language of science.

Check it out: The scientists who created the message, Dr. Frank Drake and Carl Sagan (who also earned a PhD but is generally referred to without the “Dr.” title), chose to code a message as 1,679 binary digits. “Binary digits” are zeroes and ones, which are useful in communicating with aliens because zeroes and ones can represent off and on, or black and white. If you arrange the off/on black/white bits into a rectangular grid, you can create a picture. As a matter of fact, we humans do this all the time with our computer graphics! Even the text on our screens is created by streams of binary digits that code for pixels...

So, how would the aliens know what size of rectangular grid to create to see the picture we were trying to send? That's where the number 1,679 comes in...

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

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

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

The next shape, which is purple, includes the atomic numbers of the elements hydrogen, carbon, nitrogen, oxygen, and phosphorus. These are the elements that make up DNA.

The green shapes are the formulas for sugars and bases in the nucleotides of DNA.

The long white strip in the middle is the number of nucleotides in DNA.

The blue wavy lines are a picture intended to show the double helix structure of DNA.

The red portion is a picture of a human. I wish our heads—and therefore our brains—looked just a bit bigger!

The white bit in the middle of the blue line, to the left of the human, is an indication of the average height of a grown man.

The white bit to the right of the human is the approximate number of humans on Earth.

The yellow shapes are a rough picture of the solar system, with a large sun, four small inner planets, two enormous and two medium-sized gas giant planets, and a small outer planet. The planet the message is coming from is indicated by the fact that it is raised up above the others.

The lower purple shape is an outline of the radio telescope.

The white bits in the middle of the blue line, below the radio telescope, is the size of the radio telescope's dish.


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

Did you know...?

You can buy t-shirts with the whole Arecibo message imprinted on it...or just the self-portrait from the message!

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