Extraterrestrial Expertise

Regular readers of this blog know by now that I am fascinated by the possibility of life existing on other worlds. The more science learns about the broad spectrum of life here on Earth and some of its extremes, and the more exoplanets we discover, the more likely it seems that we may not be alone in the universe; that Earth is not the sole island of life, because life is so variable and planets are so abundant. This possibility of life elsewhere has captivated humans for millennia. While it remains conjecture, astronomers have embarked upon studies in recent decades that are revealing some fascinating aspects on the issue. 

We are currently engaged in various searches of the heavens, looking for a revelatory piece of evidence that we are not alone. These studies have continually evolved, as our technology has evolved. Most of these efforts have been driven by the technology that we possessed at the time we began them. What I have found fascinating, for example, is that our SETI (search for extraterrestrial intelligence) attempts have always been based upon what we could imagine alien technology might be like at the time these projects were initiated. They later became a bit outdated, as our technology advanced; so the SETI tools were accordingly updated. 

For example, many decades ago we looked into space for telltale flashes of light. Then we imagined that alien species might be sending out electromagnetic signals—radio waves. Recently, as more and more planets have been found (we have now discovered about 5000 exoplanets), some scientists maintain that we should be looking instead for how alien civilizations have altered the atmosphere of their home planets. They may have created biosignatures of gases as we have, such as oxygen and methane. 

Thus much of our search has been based on our guesses of the nature of alien technology that we had at the time. Given that our own technology has rapidly evolved and that extraterrestrial civilizations may be unimaginably advanced—how do we know that our current search methods are even sensible?

A recent question raised by some SETI researchers suggests a different approach. Rather than look for some sort of overt communication signal, might we instead seek what are called “technosignatures?” As life on Earth has evolved, our planet's atmosphere has changed (such as the increase of oxygen and methane mentioned above). Many millions of years ago carbon dioxide was the Earth’s dominant atmospheric gas, which later gave way to oxygen, with increasing touches of methane. As global warming is currently growing, however, carbon dioxide is once again increasing. We may soon be forced to choose to engage in planetary engineering, to control climate heating, since we lack the resolve to cut back on our consumption. Might we possibly be able to observe similar kinds of changes in the atmosphere of exoplanets?

As the field of SETI advances, we will likely continue to update our searches—based upon improved estimates of the possibilities and nature of advanced alien technology. Can we imagine the paths that other civilizations may have followed? If not, we may be looking down the wrong alley and missing the truth of alien technology. It's quite possible, for example, that they long ago decided to change direction, as they realized that their technology was leading them down a destructive blind alley; as we seem to be doing. Maybe they survived by moving other options higher up on their priority list—such as placing harmony and peace above technological advances.