By Tom Thompson
We have only been listening for other civilizations 60 or 70 years. So it's not surprising that contact hasn't been made. The universe has 100 billion galaxies, each containing hundreds of millions of stars. In such a big place, Earth is not likely to be the only planet where life has evolved. Then, too, our observation of the presence in the past of surface water helps to drive our determination to keep looking.
Actually communicating with extraterrestrials is probably the alien hunter's ultimate dream. Real contact is not likely to be as simple as we might hope. It's possible that another intelligent race of beings might not be thrilled to hear from us, and want to respond. What if they want to be left alone? But no matter what, there's no reason to believe in the development soon of a movie-like technology involving a universal communicator, a kind of Babel fish, as in The Hitchhiker's Guide to the Galaxy.
Even before radio was invented there were people suggesting ways to signal extraterrestrials of our presence. A Pythagoras drawn on the Siberian tundra? In fact, that was once proposed. Joseph Littrow proposed using the Sahara as a blackboard. Giant trenches were to be filled with water and then on top of that kerosene that would burn every night with a different signal every night. An environmentally better idea was when statisticians and meteorologists suggested a language using mathematics.
Scientists are convinced that, of all the possible ways to communicate, any signal coming to us from another galactic civilization will be in the form of electromagnetic waves. Planetary scientists think that practically all atmospheres are transparent to radio waves, and a significant fraction of them are also transparent to visible light.
Radio waves have the greater advantage due to the fact that stars emit relatively few radio waves, whereas they all emit a great deal of visible light. Easy detection is the goal. Of course inside the radio waves there's a wide spectrum of wavelengths to choose from, but microwave is attractive because the low noise level. A slow pulse transmission of never random prime numbers has some appeal for initiate contact. An example might be a series of prime numbers: 2 pulses, 3 pulses, 5, 7, 11 .... A signal like this necessarily implies intelligence with mathematical knowledge.
The U.S. National Aeronautics and Space Administration (NASA) has done tests using laser communication. In other words, sending radio signals with wavelengths the size of, say, a large room. Bill Nye, the head of the Planetary Society in the U.S., favors what is essentially fiber optics. You would get a lot more information, a lot more bandwidth. Inside these layers could be more layers with codified, additional messages.
Physical scientists want to focus on scientific information. Nonscientists have other priorities. We might also employ musical compositions, which are based on mathematical patterns. Based on fundamental (fMRI) and various studies mapping the brains of music listeners, we already know that music speaks to humans on a fundamental emotional level more that more closely resembles language than anything else.
Courtesy of NASA
As early as the 1960s, the Pioneer space probes attempted to encompass all of these perspectives when it was decided that a gold anodized aluminum plate would be attached to an antenna support. It tried to give a sense of our planet's life and cultural diversity, along with our scientific knowledge. There was a drawing of a human couple with undetermined racial features; Critics protested and called the drawing "Space-Porn!" Two circles symbolized the transition between two states of neutral atomic hydrogen, the most abundant substance in the universe. Beside each planet there were symbols in binary code communicating the earth's distance from the sun compared with Mercury. Finally a "star" on the left side of the plaque attempted to show the location of our planet. In addition to a repeating radio transmission, a protected disc was included with music from different cultures, and over a hundred color and black-and-white pictures from earth.
Would extraterrestrials be able to interpret all of these efforts? There might be problems with binary notation, colors, or any images. It's easy to be reminded of the Fermi Paradox. In 1950, Enrico Fermi, one of the great scientists at Los Alamos National Laboratory asked the question "Where is everybody?" Famous for good estimates from scant data, Fermi argued that it's reasonable to conclude that there must have been civilizations in the galaxy thousands of years. The most ancient of those civilizations have had enough time to communicate with us, or maybe even reach us, truly, several times. Therefore, where is everybody?
Tom Thompson writes frequently on foreign language topics. He lives in Washington, D.C.