As has so often been the case, Douglas Adams predicted it first. When he wrote the Hitchhiker’s Guide to the Galaxy, Adams created a species called the Jatravartids, small blue aliens with more than fifty arms and the distinction of being the only race to invent aerosol deodorant before the wheel. Now a new study tells us how we might find the Jatravartids, or any similar societies, by looking for effects of CFCs in the atmospheres of alien planets.
Chlorofluorocarbons, or CFCs, are artificial compounds now outlawed for most industrial purposes, but which were previously used in virtually every household aerosol product and are still produced in huge quantities as a precursor in Teflon manufacturing. CFCs are famously destructive to ozone, breaking the radiation-absorbing O3 molecules in our upper atmosphere and thinning our planetary radiation shield. Research into this effect has been almost exclusively in reference to its impact on human beings; how much more radiation will be getting in to hit us? Far less attention has gone to the idea that a thinner atmosphere will also allow more radiation out — until now.
The Blue Marble Space Institute for Science is a new, crowd-funded research group made up of astrobiologists and spectroscopists with the aim of predicting and finding unambiguous spectral evidence for intelligent life. The word unambiguous is important: While many astrobiologists believe they can identify planets with vegetation simply by looking at the light they reflect and refract, many others are skeptical. Virtually everyone can agree, however, that a planet with CFCs in the atmosphere could not have gotten them naturally — someone had to have put them there. The group hopes to find intelligent life by finding planets with spectra showing CFC content, and possibly even atmospheric breakdown like that found on Earth.
The idea of searching for intelligent extraterrestrial life via spectral assumptions is actually quite an old one. Perhaps most famously, physicist Freeman Dyson proposed that any advancing civilization will require exponentially more power as it progresses, and will eventually construct a device to capture nearly 100% of the energy from their local star. He called this hypothetical device a Dyson sphere (pictured right) and proposed that we search for extraterrestrial life by finding stars visible only in the gamma radiation range. If all of the less powerful forms of radiation are somehow blocked from reaching us, we can infer something like a Dyson sphere around the star, and thus something like an intelligent civilization to have created it.
Whether you buy Dyson’s hypothesis or not, there’s no denying that the search for life is getting increasing attention of late, especially via analysis of light. Spectroscopy recently proved that the Solar System’s most distant dwarf planet has no atmosphere to speak of, and it proved Mars was lifeless long before Curiosity was sent to ask whether it has always been. An increasingly large faction in physics is compiling a list of possible biosignifiers, telltale spikes in a light reading that imply the existence of life on the source.
Ultimately, all this talk of Dyson spheres and aerosol aliens may turn out to be utter bunk. The central conceit of the report is what really matters: that an increasingly powerful minority within astronomy is looking leverage our light-reading technology toward ending mankind’s ultimate identity crisis. The researchers have several targets for their searching, not just CFCs but the radio signature of advanced technology and even warm spots on an otherwise cold planet. They present the thought experiment of the alien astronomer who turns its telescope on Earth, and in it observes all the transformations human beings have affected. How could the alien infer anything other than the presence of an intelligent society? Blue Marble hopes to peer through their own radio telescopes and have that moment for themselves.