Trevor Noah is hilarious. Last night, on The Daily Show, he made us laugh with the BITG message proposed by NASA researchers Jonathan H. Jiang et al. What Trevor has to tell us about the message is worth every second of your time. But don’t trust me, have fun watching the video before continuing reading (here, at 8 minutes into the video).
Hard to be serious after this. However, let’s try because the message is our latest attempt to communicate with Extra-Terrestrial Intelligence. This exercise started on November 16, 1974, with the Arecibo message. Indeed, in 1974, a 1679-bit long message was broadcasted toward the M13 galaxy from the Arecibo radio telescope in Puerto Rico. It contained basic information about us and was a bitmap of 23 by 73 pixels (not 73 by 23). Since 23 and 73 are prime numbers, the idea is that the ETI would conjecture that these remarkable values – prime numbers are uncommon, and two of them even less – are an essential component of the message! Once you know that, you can reconstruct the two-dimensional bitmap—a critical step in the decoding. And a simple +1 or -1 in one of the dimensions can completely garble the message, as Andrew Read’s Mathematica demonstration shows.
Ok, now we have an image; what next? I will not go through the entire decoding in detail here. You can find it ad nauseum on the web. But to show how unlikely it is for an average pedestrian ETI (like myself to other galactic life forms), let’s focus on the top of the message. Of course, we assume ETIs know math, physics, chemistry, and astronomy and read from top to bottom and left to right – like all humans, isn’t it? The top section of the message contains the ten first numbers and how they are encoded. You guessed, right? They used a binary representation, of course. You can imagine four horizontal lines of dots.
The bottom one is just marking the position of each number. From the bottom up, the following three dot positions contain the bits of each number (noted vertically, the lower dot being the least-significand bit, and the upper dot the most-significant bit). You can now easily read 1, 2, 3, 4, 5, 6, and 7. After seven, you need more bits, and therefore they use the adjacent column to the right to encode the remainder of the bits. All the values of the message are encoded using this binary technique. Did you notice zero is missing? The first traces of zero on Earth appeared in Mesopotamia around 3 B.C., and the Mayans invented it solo circa 4 A.D.
In the next block, just under the numbers are the values: 1, 6, 7, 8, and 15. Note that they use a fourth horizontal like, a.k.a. an extra bit. That’s how 15 is a single column of four dots. I am wondering how many ETIs we lost at this point. Ah, I almost forgot. These chosen values are the atomic numbers of respectively hydrogen, carbon, nitrogen, oxygen, and phosphorus. These atoms are the building blocks of organic molecules entering our composition – and any other living forms of Earth. It certainly makes sense to us, at least.
To give you an idea of what the rest of the message contains, hang on to your knickers and enjoy the ride: the message encodes four nucleotides composing the DNA, an ill-estimate of the base pairs in our DNA, a depiction of the DNA double helix, the height of a human, a human, and the human population. The following section represents the solar system, and last but not least, the Arecibo radio telescope and its approximate diameter in meters. It seems simple written like this, but many encoding tricks are in play here. So, Trevor, are you still making fun of the nude picture?
A few other messages – Evpatoria messages – were broadcasted during the following decades, but programs like SETI essentially listen to the skies, hoping to receive a message from ETIs. Where the Arecibo message was a technology demonstrator in 1974, with limited hope for a response, the new proposed messages (BITG) target a central spot in our galaxy where the authors estimate having a high probability of intercepting ETIs. Let’s see if we will be smart enough to decode and comprehend the messages – or answers – of ETIs.
Communication with ETI is a staple of Science Fiction. I recommend two good flicks: Contact (1997 – directed by Robert Zemeckis, with Jodie Foster, Matthew McConaughey, Tom Skerritt), and Arrival (2016 – directed by Denis Villeneuve, with Amy Adams, Jeremy Renner, Forest Whitaker). Based upon Carl Sagan’s eponymic novel, Contact is close in the spirit to the Arecibo or BITG messages but ventures into the third dimension. Arrival used the services of Christopher Wolfram, the father of Mathematica. You can read up about the concepts used here.
To Trevor’s credit, Carl Sagan wrote, “Even if the aliens are short, dour, and sexually obsessed – if they’re here, I want to know about them.” Me too!