A Sign in Space

Back in the third week of October, we were finishing up solving the Schrodinger equation of the hydrogen atom in my quantum chemistry class. I end that module with a brief discussion of hydrogen’s role in mapping the universe – its abundance, and why it might be used to communicate messages with extra-terrestrials. It’s a variation of my Star Wars Day class in G-Chem, but my P-Chem students have just seen the Zeeman splitting and understand where the 21-cm wavelength line comes from. I showed the students the SETI message that was beamed out from the Arecibo telescope.

 

One of the students asked how anyone would know how to interpret the data if you didn’t have any idea what the content would be. In the movie Contact, computers solve this presumably by running all manner of decoding algorithms on the detected message. But that’s a mighty big handwave. Humans write algorithms, and they are based on having some preconceived notion of the problem we are trying to solve. But if you have no idea where to start, what do you do? You could easily misinterpret the “code” in so many ways, most of which will just be garbage.

 

Last weekend I stumbled across A Sign in Space. It’s a clever experiment. A media artist, Daniela dePaulis, in collaboration with space agencies and observatories, designed a message that was then transmitted a signal from a spacescraft which was then picked up by our ground-based telescopes, similar to those that Jodie Foster used in Contact. As to the interpretation of the stream of zeros and ones, that was turned over to the public. Citizen scientists were going to try and make sense of the data. It took a year before a father and daughter team finally cracked the code. But what was most interesting was looking through the process in which people with different expertise and all walks of life, not only speculated, but did some hard work in trying to make sense of it all. There were plenty of false trails, clever ideas, lots of humor, and I was impressed by the shared sense of people who didn’t know each other all helping solve an interesting problem.

 

The actual solution isn’t as interesting, although it continues to spark lively discussion on a Discord thread devoted to this project. The message provided a visual image of five amino acids. None of them were “canonical” amino acids and some (if not all) of them have been discovered on meteorites. They were all alpha-amino acids. It wasn’t clear if they were all-D or all-L, but folks on Discord thought they were the L optical isomer (similar to life on Earth). Three were hydrophobic with linear alkyl side chains of 2, 3 and 4 carbons respectively. One had an amine group (a “basic” amino acid) and one had a carboxylic acid group (an “acidic” amino acid). All were depicted in their non-zwitterionic form.

 

From an origins of life point of view, the basic amino acid (2,4-diaminobutyric acid) has several possible roles. As to the three hydrophobic amino acids, there are reasons why they would not have been selected for from the point of view of chemical evolution if one wanted to have a limited yet diverse set of amino acids. The branched acidic one is interesting, but more costly from a synthetic point of view. As to whether these would form some sort of code, it would be inefficient. I don’t think the artist who put this together was thinking along those lines. While we don’t know exactly how alien scientists would think and approach a problem, we human scientists can likely come up with some reasonable scenarios. If this were an actual transmission from E.T., and the message did show these five amino acids, my speculation is that they know the makeup of our proteins and are telling us that they have some additional ones we don’t have.

 

Science content aside, what I really liked about this project was the test-like conditions of what citizen science might look like if alien messages were received from outer space. There was a vast open-endedness to the possibilities even though the final “solution” was very narrow and not particularly meaningful from a natural science point of view. From a social science point of view, I think this was a creative experiment! I look forward to being surprised by the ingenuity of how to get society at large to care about science, dive into it, and experience what it’s like to solve an interesting intellectual problem collectively.