By Brandon Gage
It’s a pretty depressing and almost unbelievable prospect; that humanity could be the only intelligent species in the entire Universe. Our home galaxy, the Milky Way, contains 400 billion stars, and at least half of those stars have planets. Many of those planets are Earth-like, and we’ve found thousands of exoplanets since the first were discovered in 1992 (they’re orbiting a pulsar, which is really cool, considering pulsars are created when giant stars die in supernova explosions).
The Universe is almost 14 billion years old and our observable portion contains hundreds of billions, maybe even trillions of galaxies, each harboring hundreds of billions, or in some cases, trillions, of stars. The entire Universe, most of which will forever remain invisible to us, stretches to 100 and 150 billion light years in diameter, and it may be even bigger than that. In fact, there are more stars in the observable Universe than there are grains of sand on all the beaches on Earth. The actual number, according to cosmologists, is in the sextillions; that’s a 1 followed by 21 zeros, and likely a conservative figure (and most stars have planets orbiting them). With so many places life could have evolved, it should be safe to assume that intelligent life, like us, popped up somewhere else.
Consider: “The four most common chemically active elements in the universe—hydrogen, oxygen, carbon, and nitrogen—are the four most common elements of life on Earth. We are not simply in the universe. The universe is in us.” - Neil deGrasse Tyson
That life as we know is carbon-based isn’t surprising, because carbon can form more chemical bonds than all the other elements combined. Life is, after all, complex chemistry. Based on this fact, and given the right conditions, simple life should be everywhere. But how common is intelligent life? I suggest having some caffeine or weed handy (or both) because we’re about to work with some incomprehensibly large numbers. If your head hurts by the end of this, I’ve done my job.
Here is what we know.
We’re living in a remarkable period of history; our telescopes can see planets orbiting other stars, and in 2019, the James Webb Space Telescope will launch into space with the ability to analyze the atmospheres of exoplanets. I’m not generally the betting type, but if I were, I’d place my money on Webb detecting signs of simple life around nearby stars relatively quickly, such as an abundance of atmospheric oxygen (which requires a continuous source, as oxygen is unstable in its atomic form). Simple life as we know it is probably common in our galaxy, but what about intelligent, technologically advanced civilizations?
Let’s start by considering all the extremely unlikely events that had to occur to give humans the opportunity to evolve in the first place. Our solar system formed from a cloud of gas and dust roughly 4.5 billion years ago. During this early period gravity consolidated gas and dust into countless objects, eventually forming the eight planets, hundreds of moons, and trillions of smaller objects like asteroids and comets that orbit the Sun. Things started to quiet down after about 500 million years, following a period called the Late Heavy Bombardment. Around 4 billion years ago, the still-molten Earth was about 25 percent smaller than it is today. Then something incredible happened. An object the size of Mars slammed into the young Earth, but at just the right angle to send billions of tons of debris into orbit. This debris coalesced into our Moon, whose gravity eventually slowed and stabilized Earth’s rotation. Having a stable rotation allowed for a temperate climate and cyclical seasons. The Moon’s gravity is also responsible for Earth’s ocean tides.
The oldest evidence of life on Earth dates to 3.9 billion years ago, and for nearly three billion years, the only life on Earth was single-celled organisms. After billions of years and despite several mass extinctions, modern homo sapiens appeared in the plains of Africa around 200,000 years ago. Since then, humanity has experienced rapid societal evolution, garnering skills from cooking (likely responsible for our large brains) and agriculture to the utilization of science and technology. Humanity became an interstellar species in 2012 when Voyager 1 officially left our solar system. In 40,000 years, it will pass the nearest star system, Alpha Centauri, which is roughly 4 light years away. Incredibly, Voyager could end up the last remnant of our species as it drifts through the emptiness of interstellar space.
Is there anyone out there?
This question is as scientific as it is philosophical, and the possibilities are as profound as they are frightening. First, we need to calculate how many intelligent civilizations there could be in our galaxy, the Milky Way. In 1961, astronomer and astrophysicist Dr. Frank Drake developed a simple equation to do just that. Here’s how the Drake Equation works:
“N = The number of civilizations in the Milky Way Galaxy whose electromagnetic emissions are detectable.
R* = The rate of formation of stars suitable for the development of intelligent life.
fp = The fraction of those stars with planetary systems.
ne = The number of planets, per solar system, with an environment suitable for life.
fl = The fraction of suitable planets on which life actually appears.
fi = The fraction of life bearing planets on which intelligent life emerges.
fc = The fraction of civilizations that develop a technology that releases detectable signs of their existence into space.
L = The length of time such civilizations release detectable signals into space.”
Source: “The Drake Equation;” the Search for Extraterrestrial Intelligence (SETI)
You can plug in whatever numbers you want, but Dr. Drake’s initial educated estimate was that our galaxy should contain 10,000 intelligent civilizations, and yet, wherever we look and whatever frequency we analyze, we find nothing. No signals, no Dyson spheres, no starships, no robotic probes flying around; nothing.
If our galaxy should harbor 10,000 civilizations, and there are as many as 2 trillion galaxies in the observable Universe, intelligent life should be commonplace. Our radio and television transmissions have permeated a small volume surrounding our solar system, reaching stars as far as 100 light years from the Sun in all directions. Sure, our galaxy is 10,000 light years thick and 100,000 light years across, so our sphere of influence is quite small, and any civilization we detect should be far older and more advanced than we are. We can, however, peer far beyond our radiosphere through our most powerful visual and radio telescopes, yet humanity as neither seen nor heard anything. Nothing. Silence. Why?
The Fermi Paradox, named after physicist Enrico Fermi (who invented fission reactors), examines this possibility quite nicely, and it really is a remarkably strong and compelling argument. SETI explains, “Fermi realized that any civilization with a modest amount of rocket technology and an immodest amount of imperial incentive could rapidly colonize the entire Galaxy. Within ten million years, every star system could be brought under the wing of empire. Ten million years may sound long, but in fact it's quite short compared with the age of the Galaxy, which is roughly ten thousand million years. Colonization of the Milky Way should be a quick exercise. So what Fermi immediately realized was that the aliens have had more than enough time to pepper the Galaxy with their presence. But looking around, he didn't see any clear indication that they're out and about. This prompted Fermi to ask what was (to him) an obvious question: "where is everybody?"”
Humanity may be alone in the Universe.
If this is the case, then there is no Fermi Paradox at all, and the Drake Equation is a meaningless and arbitrary manipulation of numbers. Considering the numerous events and tiny odds of humanity existing in the first place, it’s probably safe to assume that intelligent life takes a long time to evolve, and, during that time, life must evolve in such a way that allows intelligence to appear in the first place. Furthermore, intelligent civilizations have to survive long enough to reach the technical capabilities of letting their presence be known to the rest of, well, everything, without first destroying themselves or getting wiped out by some giant cataclysm, like a gamma ray burst or an asteroid impact.
Because the early Universe contained hydrogen almost exclusively, the first stars in the Universe were huge, as in, really really huge. They lived for only a couple million years before dying in supernova explosions, spewing out heavy elements and then collapsing into black holes. These black holes, over time, merged into supermassive black holes, which now lie at the centers of every large galaxy. Galaxies, it is thought, formed in tandem with supermassive black holes. Remember, every galaxy contains hundreds of billions and in some cases even trillions of stars.
Fast forward a few billion years to the formation of the Milky Way. In its infancy, most of the stars would have been large and short-lived. Stars like the Sun are the children and grandchildren of massive stars that went supernova billions of years ago. Putting all this into context, our solar system has only existed for about 1/3 of the life of the Universe; that’s how long it took for the conditions to be right for our Sun and the planets in our solar system to form. Therefore, this is likely the case in every other galaxy. Of course, this alone does not necessarily mean there isn’t anyone else out there, but it does lend credence to that possibility.
I’d like to propose another, more existentially terrifying idea: that humans are the first intelligent, technologically-capable species in the Universe.
At 14 billion years old, the Universe is, amazingly, quite young. Stars will continue to form, shine, and die for another 100 trillion years. If we shrink this down to a human scale, say, 100 trillion years compressed into 365 days, then humanity has only existed for 1/15 of a second. Therefore, it’s reasonable to infer that there’s more time and opportunity ahead of us than behind us for other intelligent life to pop up somewhere else. If this is the case, our role in the cosmos changes dramatically. We have the responsibility to preserve our planet and spread out beyond it, not only for our own survival, but for the propagation of life itself. If our consciousness and intelligence are the Universe’s way of discovering itself, then it is our duty to protect life and spread out beyond our pale blue dot.
If you’ve ever asked what the meaning of life is, it could very well be to spread the seeds of sentience and consciousness throughout the Universe. Being the first life in the Universe capable of carrying this enormous burden and taking advantage of this boundless opportunity is how we need to start behaving. For all we know, propagating sentience and consciousness throughout the cosmos could very well be the meaning of why we are here, and we only get one chance. Granted, the Universe never makes just one of anything, however, there must be a first for everything.
Humanity may be alone in the Universe. We best start acting like it.