Given the vastness of the universe, it's possible that 1 billion intelligent civilizations exist.
So why is there no sign of these civilizations?
It is likely that all advanced civilizations are eventually destroyed by a "Great Filter". And it's probable that humanity is currently going through its Great Filter right now.
First, Let's Examine Why Alien Life Should Exist
The Milky Way, our galaxy, is home to approximately 100 to 400 billion stars. Assuming that a portion of these stars are central to solar systems, similar to our own, it's conceivable that the Milky Way could contain tens to hundreds of billions of such systems.
Adding to this, the discovery of thousands of exoplanets, many found in systems with multiple planets through missions like Kepler and TESS, reinforces the idea that planetary systems are a common feature around stars. This widespread occurrence of exoplanets suggests that a significant majority of stars throughout the universe might host their own solar systems.
Expanding this view to the larger cosmos, with an estimated 2 trillion galaxies in the observable universe, each potentially holding as many stars as the Milky Way on average, the numbers become even more astronomical. This implies a universe where hundreds of trillions to quadrillions of solar systems could exist, each with its unique characteristics and potentially life-supporting conditions.
To crudely estimate the number of solar systems with planets that have conditions favorable to life, let's use the higher end of the estimate: one quadrillion solar systems in the universe. If 1% of these solar systems have planets with conditions favorable to life, there could potentially be about 10 trillion solar systems with planets that have conditions conducive to life.
Assuming that 1% of the planets with conditions favorable for life actually develop life, from the 10 trillion potential life-supporting solar systems, this would imply the existence of approximately 100 billion planets where life has developed.
Rudimentary life faces its own set of Great Filters so let's exclude those that get snuffed out and assume a portion reach an advanced state, like on Earth. If just 1% of planets with life are able to develop intelligent civilizations, from the estimated 100 billion planets with life, this would suggest the potential existence of approximately 1 billion planets with intelligent civilizations across the universe.
Now consider that the universe is 13.8 billion years old and life on Earth began approximately 3.5 to 3.8 billion years ago. If we consider the development of tools, control of fire, and early forms of communication as indicators of intelligence, then intelligent life in the form of the genus Homo has been on Earth for over 2 million years. However, the more complex behaviors associated with modern humans have been evident for about 50,000 years or more.
Given the age of the universe, there has been plenty of opportunity for life similarly or more advanced than ours to develop.
So if the probability of life elsewhere in the universe is so high, why have we never seen intelligent alien civilizations? This is referred to as the Fermi Paradox.
Do All Civilizations Self Destruct?
The Great Filter is a concept used to explain the Fermi Paradox and why, despite the vast number of potentially habitable planets in the universe, there is no observed evidence of intelligent extraterrestrial life.
The Great Filter refers to a hypothetical stage or stages in the evolution of life that are extremely difficult for life to surpass. The concept raises the question of whether there is some barrier that makes the emergence of complex life or advanced civilizations very rare or short-lived.
These barriers could include the following:
- The Emergence of Life: The transition from non-living matter to living organisms.
- The Development of Single-Celled Life: The appearance of the first simple, single-celled organisms.
- Complex Multicellular Life: The evolution from simple, single-celled organisms to complex, multicellular organisms.
- The Emergence of Intelligence and Technology: The development of species with higher intelligence and the ability to create sophisticated technology.
- The Ability to Avoid Self-Destruction: Overcoming internal and external threats that could lead to the extinction of intelligent life, such as nuclear war, environmental destruction, or catastrophic cosmic events.
As an explanation for the Fermi Paradox, the Great Filter concept suggests that if intelligent life is rare in the universe, then at least one of these stages must be exceedingly rare and difficult to achieve. This leads to two possibilities for human civilization:
- The Filter is Behind Us: This would imply that one of the early steps in the evolution of life (such as the emergence of life itself or the transition to multicellularity) is incredibly rare, and we are one of the few life forms to have made it through.
- The Filter is Ahead of Us: This more concerning possibility suggests that there is some future hurdle, potentially related to the development of advanced technology or the ability to sustain a global civilization, that most intelligent life does not overcome.
It is plausible that there are multiple Filters, some of which are behind us. But that leaves one left for humanity: self destruction.
Potential for Civilization Self-Destruction
The potential for a civilization to self-destruct encompasses a variety of scenarios, influenced by factors like technological advancement, social dynamics, environmental interactions, and governance structures. Below are the most likely ways our human civilization could self-destruct.
A nuclear war could obliterate civilization firstly through its immediate, catastrophic impacts. The detonation of nuclear weapons would result in the total destruction of targeted cities and regions, killing millions instantly and demolishing essential infrastructure. The aftermath would be characterized by widespread death and suffering due to intense heat, blast effects, and radiation exposure. This would result in overwhelming health crises, including severe burns, radiation sickness, and long-term conditions like cancer. The direct destruction of urban centers, communication networks, and essential services would disrupt the very fabric of societal organization, leading to chaos and a breakdown in law and order.
Further exacerbating this devastation would be the long-term environmental and economic consequences. A nuclear winter, triggered by smoke and soot from fires blocking sunlight, would lead to a drastic drop in global temperatures, disrupting agriculture and leading to widespread famine. This environmental collapse would be coupled with the breakdown of economic systems. Global trade, financial markets, and supply chains would collapse, plunging the world into an unprecedented economic depression. The cumulative effect of these impacts would be the dismantling of the interconnected systems that sustain modern civilization, potentially leading to its total collapse. The severity of these consequences underscores the existential threat posed by nuclear war, making its prevention a paramount concern for global security and human survival.
Environmental Collapse and Climate Change
Environmental collapse and climate change pose existential threats to civilization, primarily through the gradual but relentless degradation of the ecosystems that underpin human life and society. As climate change accelerates, it leads to more extreme weather events like hurricanes, droughts, floods, and heatwaves, which in turn have devastating impacts on agriculture, fresh water supplies, and human habitability. These changes threaten food security worldwide, potentially leading to widespread famine and water scarcity. Furthermore, the rising sea levels resulting from melting polar ice caps and glaciers could inundate coastal cities, displacing millions of people and causing unprecedented migration crises. The loss of biodiversity and the collapse of ecosystems, such as coral reefs and rainforests, further exacerbate these challenges, disrupting the natural services they provide, like pollination, climate regulation, and the purification of air and water.
The secondary effects of these environmental changes could be equally catastrophic for civilization. As resources become scarce and habitable areas shrink, there's likely to be increased conflict over what remains, potentially leading to wars and widespread social unrest. Economic systems could collapse under the strain of these environmental challenges, leading to global economic instability and a decline in living standards. Moreover, the psychological impact on individuals and societies, facing the loss of their homes, livelihoods, and traditional ways of life, could lead to widespread mental health crises. In a world where the environmental foundations of civilization are crumbling, the social, economic, and political structures built upon them might also fail, leading to a potential collapse of civilization as we know it. The gradual, interconnected nature of these changes makes them particularly insidious, as the slow accumulation of impacts could ultimately reach a tipping point beyond which recovery is impossible.
The potential for nuclear war is intricately connected to climate change, with resource scarcity and conflict being key links. Climate change exacerbates resource scarcity, particularly water and arable land, heightening geopolitical tensions and potentially involving nuclear-armed states. Climate-induced migration can cause regional instability, as displaced people due to rising sea levels, droughts, and other climate-related issues escalate tensions in receiving regions, potentially involving nuclear powers. Additionally, the economic and political stresses induced by climate change can lead to increased militarization and global tension, raising the risk of nuclear conflict.
Artificial intelligence (AI) has the potential to destroy civilization if its development and deployment are mismanaged. One significant risk is the creation of AI systems that are misaligned with human values and goals. If AI becomes advanced enough to make decisions without human oversight, and its objectives are not perfectly aligned with human ethics and welfare, it could take actions that are harmful or catastrophic. This risk is exacerbated by the potential for an AI arms race, where nations or corporations prioritize power or profit over safety, leading to the development of powerful AI systems without adequate controls or understanding of their long-term behavior. Another risk is that AI could be used maliciously, with autonomous weapons or cyber-AI being used in warfare or terrorism, potentially leading to mass casualties or societal disruption.
Beyond the immediate risks of misaligned or malicious AI, there are broader societal implications that could lead to civilizational collapse. The rapid advancement of AI could lead to widespread unemployment and economic instability as machines replace human labor across various sectors. This displacement could exacerbate social inequalities and lead to widespread unrest and conflict. Additionally, the concentration of power and wealth in the hands of those who control advanced AI could lead to unprecedented levels of societal control and erosion of democratic processes. The overarching concern is that if the development of AI outpaces our ability to understand and control it, and if its benefits are not equitably distributed, the fabric of society could be irreparably damaged, leading to a breakdown of the social, economic, and political structures that support civilization.
These Are Not Theoretical Risks
There have been several instances in history where the world has come perilously close to nuclear Armageddon due to accidents, miscommunications, and political crises. Here are some notable examples:
Humanity's End Was Determined from the Start
Technological civilizations - human or alien - are built off natural resources, energy and the mindset to exploit these resources for gain. The evolutionary process elevates the most competitive and exploitative species and so the very reason for humanity's success is the cause of our inevitable collapse.
We have the foresight to anticipate our own demise, yet it is in our DNA to get more and do more. Going backwards is one of the most psychologically painful things a human can endure.
I'm reminded of the German billionaire Adolf Merckle - worth $9.2 billion in 2008 - who killed himself after losing half a billion euros on a trade that went the wrong way. He was still a billionaire, but the thought of dismantling some of his business empire and scaling down his lifestyle was unbearable. A rationale outsider would see he could have carried on with a wealthy lifestyle almost all of humanity could never experience, yet in Merckle's mind going backwards was a failure.
Similarly, saving human civilization might require we revert back to a 1950s lifestyle. Doesn't sound that bad conceptually. But when you start taking things away the idea of loss becomes unconscionable.
The moment a species learns to manipulate its environment for gain is the moment the clock starts ticking on its demise. The Great Filter of self-destruction is a key feature of all intelligent life in our universe, and it is exceedingly unlikely for any civilization to pass through successfully.
The experiment of intelligent life on Earth has run its course. This was always going to be temporary.
Don't give up trying. Quite the opposite. I think we must slow down and appreciate that we are the lucky ones who get to experience conscious life - happiness, love, pleasure and pain.