The current estimate for the number of stars with Earth-sized planets orbiting in the habitable zone is about one in four, according to Dr. Daniel Apai Principal Investigator for Project EOS. Other researchers estimates range from as few as 5 percent to more than 100 percent, which means that more than one exist per star.
Despite even the most optimistic statistics, the only life found in the universe is that which is found on Earth. The life on this earth, in the form of human scientist, are compelled to search for evidence of other-life in the universe for many reasons. First of all, we want to know if it can happen. Moreover, we want to know what it is like compared to life on Earth. But ultimately, everything learned from this kind of research, will illuminate what life is and how it arose on this tiny speck of dust.
How might scientist first find life?
There are different kinds of life, and each kind will have different ways to signal their presence. The first kind of life is very simple. This kind of life is usually single celled and hasn’t had time yet to greatly impact the planet it inhabits. This kind of life would be undetectable.
For a long time, life on Earth would have been undetectable. It wasn’t until cyanobacteria, or blue-green algae, evolved chloroplasts that oxygen started to build up in significant amounts in Earth’s early atmosphere as a byproduct of photosynthesis. Oxygen was poisonous to the life that previously inhabited the Earth, so they died out. Today, all of the plants on Earth turn carbon dioxide into oxygen for energy (photosynthesis). Oxygen is a very unstable and reactive gas, so unless life is present to be constantly creating it, it won’t stick around long. So hypothetically, if an alien was observing Earth using spectroscopy and remote sensing, the alien might note the oxygen in the atmosphere and conclude that Earth hosts life.
Detectable life, like blue-green algae for example, doesn’t necessarily mean complex life. Complex life, like plants and animals could be even rarer.
Rarer still is the existence of intelligent life. Civilization and technology are still very new things when thought of in the timescale of the universe. The SETI Institute primarily looks for evidence of this kind of life through technological signals such as radio waves.
“I think we will most likely we will be surprised which is I think probably the most interesting aspect,” Apai said. Despite all we know about life, the signal may not even be recognizable the first time. But once life is detected for the first time, according to Apai, then finding it should become easier as time goes on.
Special and alone? Most likely not.
Some argue that maybe Earth is a fluke, and we are the one in a trillion change that life has evolved. However, Apai said, “We have yet to find any property of Earth that is truly unusual as far as we know it.” Meaning that it’s likely that these conditions could be repeated throughout the galaxy. Another reason is that we have evidence that life began very early on in the Earth’s history, suggesting that life might emerge quickly and easily.
Science fiction as motivation.
Apai discussed his motivations for taking part in the search for life, which started early in life. Apai grew up in Hungary, part of the Eastern Bloc at the time. Science fiction was one of the genres that were not censored because the government was trying to promote the idea of a brighter future through science and technology.
Apai found an interesting paradox: “Most [science fiction] express a belief that based on rational thinking and ideas you can improve society, civilization, and the life of people, so I like that, and that’s probably part of my motivation.”
What life out there means for life down here.
Later in life, once going to school for physics he became motivated by the idea of changing how people perceive the world, and wanting to answer the most fundamental questions.
Even though it’s hard to see the everyday benefits of the search for life in the universe or such similar scientific endeavors, these pursuits actually have some of the most profound impacts on society.
The ramifications that this research has is both technological, cultural and psychological. For example, studying the motion of the planets not only led to uproar in areas in the world where the church was the most influential, but people also died, science took precedence, knowledge in other fields was gained and people’s everyday thinking was transformed.
The promise of the search for life through endeavors such as Project EOS could mean many things. New technologies could be developed and used across scientific fields, our understanding of the definition of life could improve, and the understanding of our climate and our relationship to it could be strengthened. These are all things that could happen even if we don’t find life.
Imagine what could happen if we did.