“Who lives on all those stars?”
As my five-year-old daughter and I walked our dog the other night, she kept repeating her question. The night was clear, and the Milky Way was ablaze in all its glory, showering us terrestrials with infinite pinpricks of stellar light.
It is a good question, and one that has bedeviled humans since we first stood upright. After all, there are a lot of stars out there and even more planets. So, isn’t it obvious there must be life in other places out there?
Before we dive into this big kahuna of a question, a quick reminder of the kinds of numbers we are dealing with.
Earth resides in our Solar System of eight planets, which in turn resides in our Milky Way galaxy. Our galaxy is home to another 200-400 billion stars like our sun (2–4 × 1011), with countless planets orbiting those flaming engines. And there are another 100-200 billion galaxies in our universe. In all, our best fuzzy math points to 70 sextillion (7×1022) stars in the observable universe (and that is just what we can see).
These kinds of numbers beg for an analogy, especially when trying to explain them to children. So, let’s use the one most every child can grasp: for every grain of sand on every beach on our planet, there are multiple stars in our universe. And for at least tens of billions of those stars, there are probably exoplanets like Earth orbiting them. Further, the universe is almost 14 billion years old, and many stars are older than our sun, which suggests there has been a lot more time for intelligent species to have developed on other planets than on ours. Surely, some would have invented interstellar travel. And even with the slow speed of the kind of space travel we are familiar with (and hopefully more advanced aliens would have graduated from chemical propulsion to warp drive or something equally game-changing), this means there has been plenty of time (it would only take a few million years to traverse our Milky Way with even our slow rockets) for our galaxy to have been explored by other smart civilizations. And time scales aren’t the hindrance they are to us if we assume hyper-intelligent aliens would use drone ships and their own version of advanced artificial intelligence – so why haven’t we seen some of these around our pretty planet?
Back to my daughter’s question, and time to explain why this is such an apt question for a political economy forum.
There are a range of explanations that might provide enlightenment. All are intuitively compelling, but only one feels like what is happening to us humans right now.
First, contrary to the large numbers noted above, it may be that intelligent life is incredibly rare, and we really are alone in the universe. Admittedly, a lot had to go right for Earth to develop as it did: our star and planet had just the right properties and distance from each other, our planet developed a magnetosphere and plate tectonics, the chemistry of the atmosphere and oceans offers exceptional protection for life, we got pelted by big stellar rocks at the just the right times to serve as an evolutionary stimulant (sorry dinosaurs), and somehow we had a trigger that took us from prokaryotic to eukaryotic cells and then to sexual reproduction and the Cambrian explosion.
Second, maybe there is other intelligent life out there, but it existed (and maybe even visited our planet) before we humans came about. After all, humanity has been around for only 200,000 or so years (compared to our 4+ billion-year-old planet and our 14-billion-year-old universe) and it is only in the last sixty years or so that we have had sufficiently ‘advanced’ technology to listen for other life forms or to try to broadcast to them. Or perhaps there is other intelligent life out there, but it bears no resemblance to us. Maybe it lives deep underwater in buried oceans, like on the seas of Enceladus and Europa. Why would such beings care to develop spacecraft? Or conceivably intelligent life could exist and even look a bit like us, but might have long since moved away from the physical realm. Think Netflix and the metaverse in 2,000 years: humans might very well upload their consciousness into a form of AI that lives entirely in a digital realm, enabling a kind of immortality and a perpetual hedonistic form of entertainment – such a future is doubtful to lead to selfless physical planetary exploration like in Star Trek.
Or maybe intelligent life has observed humans and determined we are too immature to bother with. This ‘zoo hypothesis’ has a certain logic to it. Imagine an alien intelligence advanced enough to traverse the time scales of our galaxy visited Earth during any of the innumerable periods of terrible war and violence that mark our history – would it not be expected they might choose to leave us alone, concluding we are too primitive a form of life to bother with? If an advanced civilization came upon a planet like ours in much of the 20th century, with its inhabitants busy killing hundreds of millions of each other, as we did in World War 1 and 2, would they stay? Maybe better to keep a distance and let such primitive beings hopefully evolve. Visit the zoo from afar but don’t interact with the animals.
Third, perhaps higher civilizations know better than to seek out other forms of life. As Stephen Hawkings put it, when discussing a potentially habitable alien world known as Gliese 832c, “One day, we might receive a signal from a planet like this, but we should be wary of answering back. Meeting an advanced civilization could be like Native Americans encountering Columbus. That didn’t turn out so well.”
But there is another explanation for why we can’t find anyone else out there. It is the most parochial and depressing, and I think the most likely. It is also spot on for what we humans are doing in 2024: intelligent life inevitably destroys itself because it can’t control its technology.
Wait a second, I know what you are thinking: this whole piece is a build up to a Terminator thesis? We unlock general artificial intelligence, that can reason on its own at levels beyond that of humans, and it decides to destroy it creators?
Nope, that is not the explanation I have in mind. Nor is it that we unleash nuclear war or a biotechnology weapon that destroys humanity, though all are possible examples of how a civilization like ours might engineer its own demise with its technology.
We are an energy intensive civilization. There are more than 8 billion of us alive today, and we will surpass 10 billion by 2100. Resource depletion is all around us, the direct result of our species growth. We immodestly call this period of Earth’s history the Anthropocene, when human activity defines the planet’s geological epoch.
There are three likely trajectories through this existential period. On one end of the continuum is the ‘see no evil, hear no evil’ path: our planet’s carrying capacity becomes exhausted and we do nothing about it, leading to a mass die off and a much smaller population. On the other end is the enlightenment path: we put aside short-termism and division (across nations and inside nations) and somehow achieve sustainability, moving from fossil fuels to breakthrough new sustainable energy sources (fusion is the usual ‘Hail Mary’ example) at scale, before the Earth is permanently destabilized. In the middle is the most likely scenario: we know we have a big problem, we take halting steps at energy transition, but political dysfunction and short-termism reign supreme, and we pass critical tipping points leading to environmental ruin.
Which of these futures do you think is most likely?
As we approach 2025, with the world’s largest economy about to be led by a man who denies climate change and who sees salvation in a massive expansion of fossil fuel extraction (and whose new best friend sees species deliverance in moving to Mars) logic would suggest this middle scenario is our future.
Technology explosions have moved our species from the stone age to the agricultural age to the industrial revolution to digital dominance. In each, our energy needs have grown exponentially, as they now do again with the advent of artificial intelligence. To fuel our latest evolutionary step, we are draining our energy sources before we can effectively develop new ones. If this continues, the eventual end point will be another version of the stone age. Should it be any different for other civilizations? Is this why we can’t find anyone else out there?
A five-year-old girl is innocence personified. When my daughter looked at me, wide-eyed, wondering where all the fairies might be on those blinking lights in the sky, I could only smile. The possible explanation feels too difficult to share.
