Speaking to Aliens: The Arecibo Message

On 16th November 1974, a radio message was sent with the objective of being received by aliens. Of course, it would be fairly foolish to send the message in any of our terrestrial languages. So what is the best way to communicate with aliens?

Making it Decipherable

When we transmit communications terrestrially, the transmitters and receivers know how to decode the information. When sending a message to either many or zero alien civilisations, you can't assume they'd use any of the established systems we have here on earth.

Instead, the Arecibo Message alternated its frequency and communicated in binary, a series of either "on" or "off" signals. The message consisted of 1,679 binary signals.

If, like me, you're not a mathematician, that number probably means nothing to you. However, 1,679 is known as a semiprime, meaning that it is the product two prime numbers (numbers only divisible by themselves and one).

The number 1,679 can only be divided by 73 or 23 to give an answer that is a whole number (giving the other number as the result). This means the 1,679 signals can only be arranged rectangular image measuring 23x73 or 73x23.

If you arrange the message as 23x73, it doesn't look like anything and is nonsensical. However, if you arrange it 73x23, the message will display a simple message that aims to tell aliens who we are and what we're all about in the simplest way possible.

Keeping it Short and Simple

The Arecibo Radio Telescope

Since the transmission lasted less than three minutes, there wasn't really much time to tell the whole story of the human race. Instead, the information to transmit was carefully selected in order to "hi" in the most effective way possible:

The decimal system (the numbers from one to ten) was included.

Then the atomic number of the elements that make up our DNA, hydrogen, carbon, nitrogen, oxygen, and phosphorous.

Nucleotides, the molecules that make up our DNA, were then included. With this information,

They then gave them our double-helix structure. At this rate, the aliens basically have a snapshot of our genetic makeup. I guess if they were advanced enough, they could build their own versions of us, if they cared enough.

In case there were any doubts, an image of a stick figure was also included in order to show the aliens where our limbs and head go.

M13, the message's destination.

Since they knew who we were, and supposedly the general area of where the message was coming from, a small map of our solar system was also included which pointed out that we reside on the third planet from the sun.

Finally, a representation of the Arecibo radio telescope was included which signs off the message.

Waiting for an Answer

The Arecibo message will take 25,000 years to reach its destination. If aliens receive and decipher the message, and decide to message back immediately, it'll take another 25,000 years for us to get the answer. I wouldn't wait by the phone and nor will anyone at the Arecibo radio telescope.

In fact, the message was always thought of as a bit of a long shot and only really sent in order to show off what the Arecibo radio telescope was capable of! With that said, I still reckon communicating with alien life is an interesting idea and hope you also did!