DarkRange55
Where in the world is John Galt? 🥞
- Oct 15, 2023
- 2,234
Arthur C. Clarke once famously said that either we are alone in the universe, or we're not—and both prospects are equally terrifying.
The reality, however, is that being alone is actually the more frightening prospect. First of all, if we are truly alone, we can never prove it. We will never know whether we are the only life in the universe; we can only ever make a discovery of alien life and thereby know that we are not alone. The reason we can't know is the universe itself. It simply does not allow us to. We can only see a bubble—the observable universe. Beyond that boundary, the universe continues, whether it is only slightly larger, vastly larger, or infinite is still unknown. But no matter the case, we can never see all of it, and as a result, we can never know if we are truly alone. Time further complicates this. The farther out we look, the farther back in time we see. The most distant objects we observe come from when the universe was very young and not yet populated with the heavier elements needed for life—at least life as we know it. That reality shrinks the bubble even further.
Despite this, life itself may be easier to detect than we once thought, and it may happen within our lifetime. We can search Mars for life, and there are plans to do so. The same applies to Venus, where we can study its upper atmosphere to determine the origin of the mysterious phosphine gas. We can also investigate the many ice-shell moons in our solar system to see whether their subsurface oceans host life. It's entirely possible that we live in a star system with over a dozen independent instances of life arising. You could even make the case, as Carl Sagan once did, that the universe may allow for gas giant life. He imagined the possibility of gas giants—or even brown dwarfs—hosting complex life uniquely adapted to those environments. Think floating gas-bag organisms, unlike anything on Earth, existing in ecosystems within the upper atmospheres of gas giants, ending their life cycles by dying and falling into the crushing pressures below. In such environments, decomposition wouldn't even be a process. Something gives up the ghost and immediately drops into the gravity well, and that's the end of it.
There is also the opposite scenario. Freeman Dyson envisioned what he called "Dyson's sunflowers": life evolving on ice-shell moons that reaches through fissures in the ice to discover the sun. These organisms might evolve petal-like structures that reflect sunlight in the near-vacuum of the surface toward a central point, providing the energy needed to sustain life—a new kind of photosynthesis analogue. Dyson went even further. What if such organisms eventually became independent of their subsurface oceans, somehow freeing themselves to populate space and the star system itself? This may be a stretch, with a great deal stacked against that kind of life, but what we do know is that if such life existed in our solar system, our current instruments would not detect it. We have no idea whether the solar system has done anything like this. It is far too early to assume that because we haven't seen it, it probably doesn't exist. We're nowhere near that territory. The best way to look at the great silence is to recognize that we have only just begun looking, and it should not surprise us that we haven't yet found anything.
But time raises a deeper question. What if after centuries we still haven't seen anything, and we determine that Earth is the only body in the solar system hosting indigenous life? What if after thousands of years of studying exoplanets we still find not the slightest hint of an alien biosphere or technosignature? What if, after immense amounts of time and effort, we still appear to be alone? The wildcard here is abiogenesis—how life actually begins—and how easy or difficult it is in practice. If abiogenesis is extremely hard, we might conclude that we're not alone, just extraordinarily rare, and unlikely ever to encounter others. If it turns out to be easy, and recent work suggests parts of the process may be easier than once predicted, and yet we still see no evidence of alien life, then we face a serious conundrum: a great silence where there shouldn't be one.
It's also possible that we never fully understand abiogenesis at all, leaving the question permanently open. In recent years, however, there has been a growing skepticism toward the idea that the absence of evidence for alien life implies its nonexistence. This skepticism is problematic, because it carries implications that haven't been well explored and are, frankly, unsettling. The chief issue is the Copernican principle. At its core, it states that we occupy no privileged position in the universe. When we look out into space, it appears roughly the same in every direction. Observational astronomy relies heavily on this principle of mediocrity. If we are truly alone, however, that principle collapses.
In that scenario, Earth becomes the most privileged location in the entire universe—the one place where a certain type of organic chemistry occurs and happens nowhere else. A unique chemistry, an island of unrepeatability in an otherwise repeatable experimental science. This world then becomes something akin to the Island from Lost: the one magical place in the universe where consciousness exists, effectively allowing the universe to perceive itself. In that case, we are magical unicorns. But the problem of being alone runs much deeper.
In science, when you observe something—say, an asteroid—and you see it relatively easily, you assume it's part of a larger population. If you spot one asteroid right away, continued observation will almost certainly reveal many more. For some reason, this logic is often not applied to skepticism about alien life. We ourselves prove that civilization can happen. We are someone else's alien civilization. Why, then, wouldn't it be reasonable to expect that our civilization is just one of many, of any size, in the universe? We haven't seen others yet, but absence of evidence is not evidence of absence.
This is why most scientists assume alien life exists somewhere. It's the simplest explanation—an application of Occam's razor—driven largely by the sheer number of opportunities for it to arise. Stars capable of hosting habitable zones are the most common stars in the universe by far, and exoplanets are not rare. We've already discovered thousands, including planets within habitable zones, such as those in the TRAPPIST-1 system. This is where the odds become staggering. The observable universe contains an estimated 200 sextillion stars. Even taking an extremely conservative view—assuming only half of one percent of stars have suitable planets in their habitable zones—the odds of the Sun being the only star hosting life become astronomical. If we are alone, we have beaten some of the worst odds imaginable. And if that's the case, make no mistake: you are among the rarest and most important occurrences in the entire universe. Your very existence would be beyond unlikely—so improbable it borders on incomprehensible. You wouldn't just be a unicorn; you would be something far stranger, a true singularity.
The simplest answer remains that the universe teems with microbial life, often produces more complex life, and occasionally gives rise to civilizations. If it doesn't, then we must seriously question the nature of the universe itself and whether what we observe truly represents reality. Without the Copernican principle, we can't know whether we occupy a privileged vantage point, and if that's the case, we can't know much of anything at all. Some people argue that such a scenario proves the existence of a deity or a simulator, but that explanation brings its own problems. If the universe exists solely for one civilization, why make the vast majority of it forever inaccessible and unobservable? Why restrict us to an observable bubble, rendering the rest useless and unreachable? That would be an inefficient and grim design. Others argue that intelligent life is simply rare. Perhaps life is common, but it rarely advances to our level. That's a valid point. There is plenty of intelligence in the animal kingdom, but none that matches ours. At the same time, we are not the only human species to have existed. Our extinct relatives used tools and fire and approached our level of cognition, suggesting that once intelligence emerges on a world, it tends to proliferate. That pattern may apply to the universe as well. Given enough time, intelligent civilizations may become more common. Still, the overarching question remains: what if, throughout our entire existence, we see no indication of alien life at all? If that is the case, then we are truly alone. And that makes for a strange, unsettling universe—a lonely one. In all the vastness and darkness of space, we would be the lone voice in the void, marooned either for a purpose or for no purpose at all.
That is what Arthur C. Clarke meant when he said the two possibilities are equally terrifying.
The reality, however, is that being alone is actually the more frightening prospect. First of all, if we are truly alone, we can never prove it. We will never know whether we are the only life in the universe; we can only ever make a discovery of alien life and thereby know that we are not alone. The reason we can't know is the universe itself. It simply does not allow us to. We can only see a bubble—the observable universe. Beyond that boundary, the universe continues, whether it is only slightly larger, vastly larger, or infinite is still unknown. But no matter the case, we can never see all of it, and as a result, we can never know if we are truly alone. Time further complicates this. The farther out we look, the farther back in time we see. The most distant objects we observe come from when the universe was very young and not yet populated with the heavier elements needed for life—at least life as we know it. That reality shrinks the bubble even further.
Despite this, life itself may be easier to detect than we once thought, and it may happen within our lifetime. We can search Mars for life, and there are plans to do so. The same applies to Venus, where we can study its upper atmosphere to determine the origin of the mysterious phosphine gas. We can also investigate the many ice-shell moons in our solar system to see whether their subsurface oceans host life. It's entirely possible that we live in a star system with over a dozen independent instances of life arising. You could even make the case, as Carl Sagan once did, that the universe may allow for gas giant life. He imagined the possibility of gas giants—or even brown dwarfs—hosting complex life uniquely adapted to those environments. Think floating gas-bag organisms, unlike anything on Earth, existing in ecosystems within the upper atmospheres of gas giants, ending their life cycles by dying and falling into the crushing pressures below. In such environments, decomposition wouldn't even be a process. Something gives up the ghost and immediately drops into the gravity well, and that's the end of it.
There is also the opposite scenario. Freeman Dyson envisioned what he called "Dyson's sunflowers": life evolving on ice-shell moons that reaches through fissures in the ice to discover the sun. These organisms might evolve petal-like structures that reflect sunlight in the near-vacuum of the surface toward a central point, providing the energy needed to sustain life—a new kind of photosynthesis analogue. Dyson went even further. What if such organisms eventually became independent of their subsurface oceans, somehow freeing themselves to populate space and the star system itself? This may be a stretch, with a great deal stacked against that kind of life, but what we do know is that if such life existed in our solar system, our current instruments would not detect it. We have no idea whether the solar system has done anything like this. It is far too early to assume that because we haven't seen it, it probably doesn't exist. We're nowhere near that territory. The best way to look at the great silence is to recognize that we have only just begun looking, and it should not surprise us that we haven't yet found anything.
But time raises a deeper question. What if after centuries we still haven't seen anything, and we determine that Earth is the only body in the solar system hosting indigenous life? What if after thousands of years of studying exoplanets we still find not the slightest hint of an alien biosphere or technosignature? What if, after immense amounts of time and effort, we still appear to be alone? The wildcard here is abiogenesis—how life actually begins—and how easy or difficult it is in practice. If abiogenesis is extremely hard, we might conclude that we're not alone, just extraordinarily rare, and unlikely ever to encounter others. If it turns out to be easy, and recent work suggests parts of the process may be easier than once predicted, and yet we still see no evidence of alien life, then we face a serious conundrum: a great silence where there shouldn't be one.
It's also possible that we never fully understand abiogenesis at all, leaving the question permanently open. In recent years, however, there has been a growing skepticism toward the idea that the absence of evidence for alien life implies its nonexistence. This skepticism is problematic, because it carries implications that haven't been well explored and are, frankly, unsettling. The chief issue is the Copernican principle. At its core, it states that we occupy no privileged position in the universe. When we look out into space, it appears roughly the same in every direction. Observational astronomy relies heavily on this principle of mediocrity. If we are truly alone, however, that principle collapses.
In that scenario, Earth becomes the most privileged location in the entire universe—the one place where a certain type of organic chemistry occurs and happens nowhere else. A unique chemistry, an island of unrepeatability in an otherwise repeatable experimental science. This world then becomes something akin to the Island from Lost: the one magical place in the universe where consciousness exists, effectively allowing the universe to perceive itself. In that case, we are magical unicorns. But the problem of being alone runs much deeper.
In science, when you observe something—say, an asteroid—and you see it relatively easily, you assume it's part of a larger population. If you spot one asteroid right away, continued observation will almost certainly reveal many more. For some reason, this logic is often not applied to skepticism about alien life. We ourselves prove that civilization can happen. We are someone else's alien civilization. Why, then, wouldn't it be reasonable to expect that our civilization is just one of many, of any size, in the universe? We haven't seen others yet, but absence of evidence is not evidence of absence.
This is why most scientists assume alien life exists somewhere. It's the simplest explanation—an application of Occam's razor—driven largely by the sheer number of opportunities for it to arise. Stars capable of hosting habitable zones are the most common stars in the universe by far, and exoplanets are not rare. We've already discovered thousands, including planets within habitable zones, such as those in the TRAPPIST-1 system. This is where the odds become staggering. The observable universe contains an estimated 200 sextillion stars. Even taking an extremely conservative view—assuming only half of one percent of stars have suitable planets in their habitable zones—the odds of the Sun being the only star hosting life become astronomical. If we are alone, we have beaten some of the worst odds imaginable. And if that's the case, make no mistake: you are among the rarest and most important occurrences in the entire universe. Your very existence would be beyond unlikely—so improbable it borders on incomprehensible. You wouldn't just be a unicorn; you would be something far stranger, a true singularity.
The simplest answer remains that the universe teems with microbial life, often produces more complex life, and occasionally gives rise to civilizations. If it doesn't, then we must seriously question the nature of the universe itself and whether what we observe truly represents reality. Without the Copernican principle, we can't know whether we occupy a privileged vantage point, and if that's the case, we can't know much of anything at all. Some people argue that such a scenario proves the existence of a deity or a simulator, but that explanation brings its own problems. If the universe exists solely for one civilization, why make the vast majority of it forever inaccessible and unobservable? Why restrict us to an observable bubble, rendering the rest useless and unreachable? That would be an inefficient and grim design. Others argue that intelligent life is simply rare. Perhaps life is common, but it rarely advances to our level. That's a valid point. There is plenty of intelligence in the animal kingdom, but none that matches ours. At the same time, we are not the only human species to have existed. Our extinct relatives used tools and fire and approached our level of cognition, suggesting that once intelligence emerges on a world, it tends to proliferate. That pattern may apply to the universe as well. Given enough time, intelligent civilizations may become more common. Still, the overarching question remains: what if, throughout our entire existence, we see no indication of alien life at all? If that is the case, then we are truly alone. And that makes for a strange, unsettling universe—a lonely one. In all the vastness and darkness of space, we would be the lone voice in the void, marooned either for a purpose or for no purpose at all.
That is what Arthur C. Clarke meant when he said the two possibilities are equally terrifying.
