Is humanity the only intelligent form of life in the universe?
Throughout human history, the glistening, glowing stars above have been the object of unsatiable fascination. Time and time again, we have pondered deeply about why they shine and how they came to be. Indeed, many of our earliest societies and cultures revered the beauty of the heavens above, and we continue to use the stars as beacons for navigational purposes well into the 21st century. Over the last hundred years, and since the explosion of science’s prominence in society, humanity has been able to obtain a broader glimpse of our precarious position in space. As technology continued to advance, we became equipped to comprehend the very high probability of life’s existence elsewhere. Soon, it became evident that the chemicals essential for all living things can be found in abundance throughout our solar system — even on comets. Therefore, given the fact that there are high amounts of the building blocks essential for life to form in our solar system, there must be some other place in the universe just like Earth — where both the chemicals and the chemistry coalesce to create life.
Since the probability of life existing is greater than 0 (if you are reading this, you can safely assume that you are alive in the universe), it would be logical to think that there have to be living things somewhere in space. This simply boils down to a numbers game. Our observable universe contains approximately seventy sextillion (7 x 10²²) stars — a quantity so astronomically large that it is hard to put into context. On top of that, most star systems we have encountered thus far in the universe have a unique set of planets. This, in turn, implies that there is a near infinite number of planets in our observable universe. As such, given the fact that life indeed can exist on a planet, as it does here on Earth, the probability must be near certainty that there is at least one other exoplanet capable of undergoing chemistry conducive to abiogenesis, or the creation of life, from the vast quantitates of its building blocks scattered throughout space.
Intriguingly, in spite of the huge number of planets and star systems visible to us, we have yet to find any compelling evidence of life in the universe. How can this be, considering that all of the building blocks essential for life have been found on multiple planets both within our solar system and outside of it? Just as perplexed as you and I happen to be with this, researchers decided to create an equation, called the Drake Equation, to mathematically approximate the number of intelligent civilizations capable of existing nearby our own. Once the numbers were crunched, the results suggested that around 20 intelligent civilizations should be expected to exist in our galactic neighborhood. Yet, in spite of this, we haven’t detected evidence for a single one. Scientists have since continued to develop unique theories attempting to explain why we may not have encountered intelligent life outside of Earth. However, nothing to date has been able to provide a concrete answer to the very question of where they are. On top of that, unfortunately, we have yet to receive any response to the countless signals we have divulged into the void. Understanding the paradoxical nature of this observed lack of extraterrestrial intelligent life in the universe may have implications pertaining to the human condition and our precarious position on this pale blue dot.
What is The Fermi Paradox?
Enrico Fermi, a renowned physicist who assisted with building the world’s first nuclear reactor for the Manhattan Project, came to a stunning realization during the summer of 1950. During his time at Los Alamos, Fermi found it odd, considering how vast the universe is and that the chemical building blocks of life are scattered throughout it, that other forms of intelligent life seemingly do not exist. This strange paradox of the high probability of living beings existing throughout the universe, yet thus far only being found on Earth, has been deemed the Fermi Paradox. It led to the scientists famously asking the question: “Where are they [aliens]?” Since the inception of this paradox, researchers have attempted to solve this mysterious phenomenon to no avail. Three solutions appear to be the most prominent, though each has its unique set of drawbacks.
Scenario 1: Life Blows Itself Up
As technology grows and progresses, something else continues to move forward, too. The Atomic Bulletin’s doomsday clock increasingly inches towards midnight, and once it hits that hour, marks a very high probability of the likelihood of humanity’s self-implosion. The Atomic Bulletin writes:
“The Doomsday Clock is a design that warns the public about how close we are to destroying our world with dangerous technologies of our own making. It is a metaphor, a reminder of the perils we must address if we are to survive on the planet.”
The reasoning to this solution of the Fermi Paradox is simple, yet rather depressing: sentient beings have the propensity to inflict catastrophic self-harm with the technology they develop. Because of this, all intelligent civilizations in the universe invariably destroy themselves with their own weapons of mass destruction. Perhaps, these events of self-destruction can explain why nothing has been able to respond to our messages being hurled across the vast expanses of space.
Tragically, the idea that intelligent civilizations are capable of self-annihilation seems quite probable here on Earth, especially considering that many of the 20th century’s most prevalent technological advancements occurred during periods of war, not peace. As our ability to annihilate ourselves exponentially increases with newfound weapons development, the odds of it happening gradually approach one over an increasing interval of time. Mathematically, the idea that something will occur over an incredibly long period of time if the chancers of it happening are nonzero has been expressed in the Borel–Cantelli lemma. It states that, under some instances, the probability of an event must either be zero or one over a given interval. If this can be extrapolated to the likelihood that intelligent civilizations will ultimately wield their weapons upon themselves, it could explain why there is no sentience recorded outside of Earth.
“In our obscurity — in all this vastness — there is no hint that help will come from elsewhere to save us from ourselves. It is up to us.” — Karl Sagan
Scenario 2: The Occurrence of Intelligent Life is Rare
Perhaps life does exist in the universe, after all. However, under the solution posed by the Great Filter, it would not be very likely for that life to possess intelligence. This idea was coined initially by the economist Robin Hanson. From a biological perspective, his theory is sound. In the context of our path to intelligence, the necessary evolutionary history required for the selective pressures we faced was vast — with a timescale in the span of billions of years. Furthermore, even though there have been an incredibly high number of different species of organisms recorded here on Earth, only one has been capable of intelligence conducive to the creation of technology: Homo sapiens. In order for our existence to have happened, per the Great Filter, a series of sequential events must have taken place that are unequivocally rare on their own, nonetheless in tandem.
For intelligent life to exist in the universe, according to the Great Filter, it must overcome the following hurdles:
- Thermodynamic stability needs to exist for life. Therefore, life has to be located in a modest energy star system with a planet proximally located in its star’s habitable zone.
- The storage containing molecules of life (RNA or DNA, we aren’t sure which came first) must somehow form, be relatively stable. and have the capability of self-catalyzing reactions essential for living beings to exist.
- From the building blocks of life, single cellularity has to emerge. The single-celled organisms must be capable of storing and passing on information without too much change.
- Upon the emergence of single-celled organisms, there must be some form of sexual reproduction or viral/ transposable element like activity sufficient to drive the stochastic variation essential for evolution in the storage containing material of these cells.
- From single-celled life, multi-cellular organisms must arise. These need to possess cells that are able to become differentiated and have unique functions while possessing the exact same storage material. For instance, the cells which make up our kidneys, livers, and hearts all have the same DNA. It is simply the genes being expressed in each cell type that makes them different.
- There must be development of and evolutionary selection for large organisms with a central nervous system. Furthermore, there must be sufficient variations in the capabilities of storage material expression in cells to ensure these nervous system-like organoids are able to exist.
- The selection pressure for a nervous system must additionally compound with pressure for communication, opposable thumbs, and the ability to invent tools via manipulating the environment in a precise manner.
- Upon being able to invent tools, a stable means of food production through environmental manipulation has to follow. The agricultural revolution will allow for the essential requirement of any space-faring civilization — specialization. Having the time and ability for talented individuals to be devoted to scientific discovery catalyzes the developments our own civilization has witnessed over the last ten thousand years. That being said, there are additional prerequisites for the development of agriculture, such as a stable climate, reliable food sources capable of being cultivated, and a populous willing to transition from the hunter-gatherer lifestyle to agrarian society.
- After security in food has been achieved, technological advancement has to follow sufficient for interplanetary colonization before a civilization of sentient beings destroys itself. This is a difficult feat, and is something that we have yet to accomplish.
However, if the Great Filter is real, and the barriers which must be traversed for life to form are nearly impossible to circumnavigate, there would likely not be life anywhere else in the universe. Furthermore, it implies the question of how life came to emerge here on Earth in the first place if the chain of events essential for its formation are so rare. Additionally, since there are so many planets in the universe, there likely must have been at least one other instance wherein the necessary events sufficient for the rise of an intelligent civilization here on Earth were replicated.
Scenario 3: Intelligent Life is Quiet for a Reason
Since the odds of intelligent life in the universe seem relatively high, why is the universe so quiet? If life were to exist, surely it, just like us, would want to feel the reassurance of not being alone. That being said, if intelligent civilizations are quiet, perhaps there is a rationale behind this observed silence. The Dark Forest is a terrifying solution to the Fermi Paradox. The idea behind it stems in part from game theory and utilizes the notion that the optimal survival of a sentient species is dependent on the way it chooses to engage in communication with its broader surroundings. Space is a large, empty, vast space that has the potential to contain a wide variety of unknowns. Sending a message into that unknown could lead to a wide variety of potential outcomes upon being received and, by that virtue, places an inherent risk not only on the civilization which sent the message but on the planet of its origin.
It may be the case that projecting any sign of life into space for others to pick up on has the potential to cause doomsday for the sender. Unfortunately, we on Earth have already sent countless signals and messages into space. We continue to do so even now through the use of devices like cell phones, radios, and satellites. Fortunately for us, any signals or messages we have emitted into the vacuum of space have yet to travel meaningfully far, with the oldest of signals being radio waves from the first telegraph of 1901. Waves from that telegraph have reached at most one-hundred and twenty lightyears. Therefore, over time and distance, the probability that someone or something hears a signal indicative of life here on Earth will grow. Who or what will be on the other end of our message has direct consequences for our planet and species as a whole.
From this conundrum of silence emerged a refined Dark Forest hypothesis. The refined Dark Forest postulates that whoever or whatever may be listening to signals sent from other planets could be in possession of technology more advanced than the sender’s own. The idea suggests that there likely is sentient life in the vast expanses of space, yet with a twist. In the Dark Forest, young, naive civilizations which dare to reveal themselves to the void of the universe put themselves at the plausible risk of falling victim to the dominion of far more powerful civilizations bent on conquest or destruction. As such, due to the inherent threats posed by sending communications deep into space, and considering that the recipient(s) of communications sent into space would not be known, humanity has taken an incredible gamble. The results of this may not be felt in our lifetime. Yet, as our radio waves continue to travel farther, the odds someone or something listens in with evil intentions increases.
Due to the observed silence in the universe from regions potentially capable of harboring life, it is quite possible that the only intelligent civilizations left standing the test of time happened to be the ones which remained quiet. This may explain why all of our attempts to contact life outside of our solar system have gone unanswered, and thereby is a potential solution to the Fermi Paradox.
The logic here is that the subjugation or destruction of younger civilizations at the hands of more advanced ones could serve as an effective way to prevent potential existential threats from emerging over time and thus is a fantastic preventative mechanism. On the other hand, it could also be the case that these more advanced civilizations enjoy the thrill of the hunt, just as some animals here on Earth do, and, thereby, may seek out freshly minted civilizations to exterminate. Because the universe is over thirteen billion years old, and life on Earth is about two billion years of age, there is a higher than zero chance that other civilizations have developed ahead of us. Over the last hundred years alone, humanity has made a dizzying amount of scientific breakthroughs ranging from landing a man on the Moon, to the internet, to gene editing. Imagine if a society had two million years to make such progress, even if not unabated!
Scenario 4: Are we the Predator or the Prey?
Here, I postulate that the idea of the Dark Forest is indeed sound. However, the fulfilment of the Fermi Paradox may take place for another reason unaccounted for. As established in the Dark Forest, civilizations likely have a tendency to remain as quiet as can be or contextually limit their ability to be detected by specific civilizations in order to avoid unnecessary, existential threats. The louder civilizations likely feel safe and secure in their position in the universe, or at least have the ability to potentially navigate the consequences of unintended contact with another. In this instance, could it be that humanity’s messages into the void continue to fall on deaf ears by virtue of the fact that our civilization has a history of incredible violence? Strikingly, humans have been in a situation similar to the one postulated in the Dark Forest, particularly during the age of exploration, during which humans from Europe first encountered natives of the New World.
When Europeans first came to the Americas, instead of befriending the inhabitants who had spent thousands of years building complex civilizations, they turned to genocide, exploitation, and slavery. Within a hundred years of Western expansion in the New World, the population of the native peoples had plummeted from its value before 1500. Furthermore, every major civilization that had existed in the Americas prior to European colonization was decisively conquered, exploited, and destroyed. This carnage of violence was inflicted by humans on humans and says volumes about how we may encounter the unknown civilizations in the cosmic vacuum of space.
Additionally, we have a track record of turmoil, war, and in-fighting among ourselves that extends far beyond our arrival to the New World. Across the globe, and in every major civilization, there has been conflict which at one point turned into warfare. With that in mind, would it be surprising if intelligent life were to have heard our messages, yet concluded that we may be a threat to their existence? Perhaps this observed phenomenon of silence from the universe stems from fear of being seen by none other than the sender?
To play one’s hand without being able to predict the outcome is a very risky maneuver. If an alien species were to openly communicate with another, the idea that it would choose to do so with our own is quite unlikely. Given humanity’s track record of inflicting incredible monstrosities upon itself, is there ample evidence to suggest that humans would not do the same to them? As the old adage goes, “The road to Hell is paved with good intentions,” and perhaps the noble attempt of contact with an extraterrestrial civilization could pave the way to their demise. When confronted with a horrifying unknown, there is a tendency among us to initially act with violence. In times of war, for instance, the order “Shoot first, ask [questions] later,” encapsulates this aspect of our nature to occasionally face the unknown with aggression.
Additionally, the time it would take for alien civilizations to potentially reach our own could be in the span of hundreds or even thousands of years, depending on their location, alongside speed of travel. Considering the incredible amount of technological progress we have made in merely fifty years, and the fact that Moore’s Law still holds true more than five decades after its inception, the rate of advancement by humanity may in and of itself be a deterrent from contact by a predatory alien civilization.
The Big Takeaways
The probability of another form of intelligent life somewhere, anywhere in the vastness of our universe is quite high. However, paradoxically, we have yet to detect any noticeable signals or signs from space that would be indicative of intelligence existing in the universe. Given the relatively high potential for life to form spontaneously outside of our solar system, the resulting conundrum, coined the Fermi Paradox, has yet to be fully resolved. Maybe the circumstances required for intelligent life are actually much less probable than anticipated, and the Great Filter was indeed such an exceptional rarity to overcome that it never has happened elsewhere in the history of the universe.
Another answer to the paradox may be that life capable of sending signals to us perished before ever receiving our own. As radio waves travel relatively slowly, any civilization outside of our solar system with the capacity to detect our emissions may have died by its own technology before being able to send anything back. Tragically, the odds of such an event happening here on Earth grows every year with the advent of increasingly powerful weapons technology.
Potentially, as time progresses, and as our radio waves emanate deeper into the cosmos, we might ultimately receive a response indicative of intelligent life with advanced technology outside of our pale blue dot by a civilization much like our own, thereby casting the Dark Forest Theory aside. Conversely, sentient life in the universe may have heard our signals with the understanding that they will one day lead to our demise at the hands of a civilization much more powerful than any we could ever dream of. There may be an additional comprehension that humans have been quite aggressive as a species, considering our track record of violence, which could be learned through the plethora of radio waves we have sent into space. This insight into human nature might be sufficient to provide the basis for silence, as an extraterrestrial civilization only slightly more advanced than our own may easily recognize the dangers of humanity, yet would not have the means to address them due to limitations imposed by space travel coupled with our exponential rate of technological progression.
So, could it be that we truly are alone in the vast, cosmic scale of the universe? Unfortunately, it’s too early to know the answer to such a profound question. As time progresses, a better picture will emerge capable of providing a more solidified understanding of this conundrum. For now, though, the jury’s still out.
