The prospect of the existence of extraterrestrial life has both fascinated and bewildered mankind throughout history. Scientists have long been searching for signs of alien life on other planets based on the qualities that approximate life on earth, such as the existence of water. But what if we've missed the mark by limiting our definition of "life" only to what is familiar?
By redefining the unique attributes of life itself, as well as how it emerges and thrives, we can not only conduct better-informed searches for extraterrestrial life, but in the process we can learn more about the nature of our own lives and chart our fate in the future.
We live in an age in which existential crises like climate change, supervolcanoes, and nuclear war are ever-present threats to the future of our planet. If other forms of life can exist elsewhere in the galaxy, then perhaps there's a possibility that we could too. So, what exactly should we be looking for out there?
What Might Extraterrestrial Life Look Like?
To assume that life can only exist within the parameters with which we're familiar could be making us blind to a host of other possibilities. Dr. Sara Walker believes: "We really need a more general definition for life that doesn't depend on the specific chemistry that life on Earth uses."
Walker is an astrobiologist, theoretical physicist, and professor at Arizona State University who is questioning the very nature of life and how we're attempting to find it elsewhere. To her, our definition of life should include things like the existence of technology. "I would define life as the set of all things that require information to produce them. In that sense, I mean technology is life because certainly, a computer doesn't appear out of nowhere," Walker explains.
Dr. Sara Walker
"We really need a more general definition for life that doesn't depend on the specific chemistry that life on Earth uses."
In order for a piece of technology to exist, it had to have been created by a living being. So, to discover a piece of technology amid the expanse of the universe is to discover the evidence of creativity and life itself.
"Life is literally the physics of creativity, it's the creative process in the universe," Walker describes. "It's not an individual in that process, it's the entire process of: how does information originate in the universe, and how does it expand through space and time to construct all of the things that we associate with life?"
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These seemingly abstract definitions of life are exactly the sort of thinking that's been missing from our previous approach to discovering extraterrestrials. It's possible that we have already encountered extraterrestrial life but were not able to recognize it because we were relying on our limited notion of what life is to begin with.
Rethinking the Search for Life on Other Planets
"To really understand the possibilities for life we have to discover a second example somewhere else," Walker says. Some think this second example has already been spotted.
Phosphines, gaseous chemical compounds of phosphorus and hydrogen, and potential biomarkers, were recently discovered in the atmosphere of Venus. The planet, due to its close proximity to the sun and thick atmosphere, has a surface temperature of nearly 900 degrees Fahrenheit.
Hot temperatures, along with a lack of water and nutrients, make Venus hostile to life as we know it. But it could make the planet livable for life as we don't know it. Researchers are pointing to the possibility that the phosphine indicates some form of life on Venus.
One of these researchers, a planetary scientist at MIT named Sara Seager, says, "By our phosphine gas discovery, we have raised Venus higher up on that ladder of interesting targets, and we hope that our discovery motivates focused space missions to go to Venus, to look for other gases, more gaseous signs of life, and even life itself."
Researchers are pointing to the possibility that the phosphine indicates some form of life on Venus.
So, do aliens exist? While the question remains unanswered, a broadening of the parameters through which we hypothesize might help expedite their discovery. As we continue to seek out life which exists outside of our biosphere, we need to get creative and imagine the unimaginable.
For centuries, seekers and dreamers have examined the night sky, wondering if we're truly alone in the universe or if, somewhere out there, extraterrestrial life exists. But it's very possible that many of the people who have previously searched for proof of aliens have done so in vain, because of the extremely narrow assumptions their efforts were based upon.
While we look to the stars for answers and reconceptualize the way in which we consider the limitless possibilities of the universe, we must consider that mankind and the world in which it exists are extraordinarily unique and special. If something else does exist out there, it's likely that it's just as unique as we are.