What Exactly is the Fermi Paradox?

The Fermi Paradox arises from the inquiry: if extraterrestrial life is prevalent in the universe, why have we not yet made contact? Countless novels, podcasts, films, and games explore themes of alien encounters or invasions. Yet, real-life evidence of alien visitors remains conspicuously absent.

This paradox becomes even more perplexing when considering that NASA maintains an ongoing tally of newly discovered exoplanets (planets beyond our solar system), with over 5,000 confirmed and nearly 4,000 planetary systems identified as of this writing. Given the rich biodiversity on Earth, one would think that life exists on at least a few of these distant worlds.

Experts remain divided on potential explanations, but a multitude of theories exists. It’s entertaining to contemplate our own hypotheses, and I have one I’ll share later. But first, let’s explore some fascinating ideas I uncovered during my research—most of which seem credible through simple reasoning and basic mathematics.

The Journey Has Just Begun

To start, the first exoplanet was only identified in 1992—merely three decades ago. While our technology is advancing rapidly, we are still at the nascent stage of this exploration. Given our progress in just 30 years, it’s likely to be quite a while before we embark on serious missions to other exoplanets.

Mars is the primary focus of our current exploratory efforts. Almost 60 years have elapsed since NASA launched Mariner 3, which failed when its solar panels did not deploy. Although we’ve made considerable advancements since then, human missions to Mars remain years away, and we know such plans often encounter unexpected delays.

Even if we reach Mars, it may take several more decades, if not centuries, before human exploration of exoplanets becomes feasible. Perhaps a groundbreaking scientific discovery could expedite this process.

The Challenge of Vast Distances

Another significant barrier to our search for extraterrestrial life is our relatively brief lifespans, which are incompatible with the requirements for long-distance space travel. The nearest star system to us is Alpha Centauri, situated over four light-years away—meaning it would take over four years to reach it if traveling at the speed of light.

Consider how long it would take us to reach Alpha Centauri with our current propulsion systems. It’s estimated that a journey to Mars takes about seven months, while one light-year equates to approximately 6 trillion miles.

In February 2022, researchers from Penn Engineering and the Breakthrough Starshot initiative proposed a method to reach Alpha Centauri in 20 years using a specially designed solar sail. This technology is thrilling, but even if successful, it will still be decades before we can send humans to that star system.

If we are struggling to explore beyond our solar system despite our advancements, just imagine the level of sophistication another civilization would need to possess to locate and communicate with us. Could it be that an alien species is observing us but lacks the technological capability to make contact? Are we their reality show?

Statistics and the Drake Equation

Given the multitude of planets and stars in the universe, sheer probability suggests that the likelihood of two intelligent species existing simultaneously, evolving along similar technological trajectories, and residing within reachable distances is exceedingly low.

The Drake Equation, which you may know, attempts to quantify these odds. Formulated by astronomer Frank Drake in the 1960s, it estimates the number (N) of civilizations transmitting signals within the Milky Way, based on seven variables:

1. The rate of star formation conducive to planets capable of supporting life.
2. The fraction of those stars that have planets.
3. The average number of planets that can support life per solar system.
4. The fraction of those planets that actually develop life.
5. The fraction of planets where intelligent life arises.
6. The fraction of civilizations that develop technology advanced enough for us to detect.
7. The average duration of time civilizations produce detectable signals.

When combined, the equation looks like this:

Image Source: Screenshot from the Planetary Society

In theory, the Drake Equation could yield valuable insights. However, the challenge lies in the fact that we lack sufficient data to input into it. While some variables, such as the star formation rate in the Milky Way, are relatively accessible, determining the fraction of planets where life emerges—and how advanced that life may be—is far more elusive.

Thus, until our technology improves to the point where we can monitor potential extraterrestrial life, the Drake Equation remains largely theoretical. Furthermore, even if we manage to apply it, we first need to confirm that life exists elsewhere.

The Concept of the Great Filter

This notion captivates me because I have often contemplated it without realizing it had already been conceptualized. The Great Filter posits that intelligent species will inevitably face extinction before they can venture far into the cosmos.

The causes of such extinction could range from climate change and asteroid impacts to self-inflicted disasters like nuclear warfare or ecological collapse. Regardless of the trigger, the Great Filter suggests that some catastrophic event will ultimately hinder a species' progress.

I frequently ponder the fate of past civilizations on Earth, contemplating whether we have experienced resets throughout our history. For instance, how did ancient peoples accomplish remarkable feats of construction? What if they, too, progressed further than we recognize, only to face calamities that set them back? The burning of the Library of Alexandria comes to mind as a possible example of lost knowledge.

A Shift in Perspective

Numerous explanations exist for why we have not encountered extraterrestrial life. Outer space is unimaginably vast, and even within our own planet, we are only beginning to scratch the surface of technological advancement.

The Drake Equation will only become relevant once we confirm the existence of alien life. Additionally, we must consider the implications of the Great Filter. Even if previous civilizations were more advanced than we realize, it's doubtful they achieved lunar landings. In contrast, we are only a few decades away from sending humans to Mars. With cutting-edge tools like the James Webb Space Telescope, scientists are equipped to analyze the atmospheres of exoplanets and identify new ones more effectively than ever before.

Given these considerations, it seems plausible that we might surpass the Great Filter. However, the question remains: will we succeed? Currently, as fascism rises globally, the specter of World War III looms. Human-induced climate change is already demonstrating its potential for devastation, leaving us woefully unprepared.

All these factors lead me to wonder: will humanity endure long enough to navigate the Great Filter, or will we fall short?

Katrina Paulson, a curious mind, explores humanity’s questions and the new discoveries she encounters. She shares her insights on Medium and through her newsletters: the free Curious Adventure Newsletter and the more detailed Curious Life version. Subscribing to either option grants access to Katrina’s articles and two years of archived content available around the clock. Subscription fees contribute to supporting her passion for exploring curiosities and sharing knowledge. Thank you for your readership; it is deeply appreciated.