Are we alone in the universe? It’s rare that you find such a question in which the answer is so profound irrespective of its conclusion. In a universe so vast and violent to be alone is both humbling and terrifying. There is some comfort, even a universal camaraderie, in finding out that we are not alone. Everyday we scan the sky searching and hoping to find someone, or something. But if aliens are in fact out there, then where are they? Why don’t we see them?
The Fermi Paradox, coined by astrophysicist Michael Hart in 1975, describes one of the most interesting dilemmas of our time. It goes something like this:
- We know that life evolved on Earth.
- We know that in the Milky Way Galaxy there are billions of solar systems with trillions stars and planets which are very similar to our own in condition and age.
- If they are similar to our own, then they are also likely filled with life.
- On some of these planets, the life will become advanced.
- We should expect that life in the Milky Way is thriving, that life is traveling between planets and solar systems, and that it would be easy to detect.
- And yet we see nothing. As of now, the universe is silent.
Before I go any further I should address the countless sightings of UFOs and extraterrestrials. I will start by saying that the majority of these claims are probably nonsense. Many are faked, are delusions, or can be explained away by factors such as weather, optical effects, camera glitches, or military aircraft and weaponry. However that does not mean that all of these sightings are fake. We may yet learn that some of these sightings are real, it is plausible. There are even some credible reports from pilots and militaries of UFO encounters. However we can not rely on these anecdotes as confirmation. We need irrefutable conclusive proof.
The Fermi Paradox challenges us to think critically. If the universe has trillions of planets like our own and many are probably filled with life that is advanced and spacefaring, then where are they? You would suspect that we would notice some signature of intelligence, possibly a communication signal, or a physical structure, and yet nothing. People have puzzled over this problem and have come up with a variety of theories.
1. It’s a secret.
Some people believe that we have already found evidence, and/or that we are currently in relationship with aliens, but governments around the world are hiding the truth from us. There is almost nothing less likely to be true than to find out that all of the world’s governments have been working together in perfect agreement to hide this information from the public. This would also include major suppression at universities, research labs, and private observatories. This would be an unbelievably difficult and shockingly successful operation if true, unlike any effort we have ever seen on Earth. While you could make the argument that it’s possible that something like the US military has information that we do not, the odds that the all of the world’s governments are involved in some gigantic conspiracy to hide aliens from us is very unlikely.
2. Life is more rare than we think.
Maybe we got the probabilities wrong. It’s possible that life starting from scratch is remarkably more rare than we previously thought. Maybe over a few billion years across trillions of planets life only started once or twice, and one of those times happened to be on Earth. Recently a new calculation of probabilities was published by Anders Sandberg and his colleagues at the University of Oxford. Factoring in more uncertainties and restructuring the numbers in a more robust way “the researchers determined that the odds that we are the only intelligent life in the Milky Way range between 53 and 99.6 percent.”(1)
The problem is that we really don’t know. We are not sure how organic compounds turn into single cell organisms and we are not sure how likely or unlikely this is to occur given the right conditions. One thing that would change our entire perspective is if we found any life, including single cell organisms, elsewhere in our own solar system. If we find life on Mars, or on a moon like Europa, and we can confirm that this life evolved independently from life on Earth, then life would have started two or three times in our own solar system alone. This would mean that life in the universe is likely extremely common. This is why finding life in our own solar system is so important, it will tell us so much about what we may expect to find across the entire universe.
3. Conditions change.
One possibility is that life is common, but for life to exist long enough on a planet to evolve into a complex civilization is very rare. We know that on our own planet it took over 4 billion years to get from a single cell organism to a human being. Over this time period the planet experienced multiple catastrophic asteroids, super volcano eruptions, as well as constant ice ages and changes in climate. It’s possible that life starts on many planets, but most planets do not stay stable for the billions of years required to meet the conditions for sustaining and developing more complex life. Our solar system has not changed very much in a long time, this has allowed our planet to remain stable and safe. We have also been relatively lucky with catastrophes. Although our planet has had significant damage from asteroids, it has not yet been destroyed. Furthermore both Jupiter and the Moon protect Earth from the majority of asteroids which would come close to our orbit. Our position in space has often been called the “Goldilock Zone”. Everything is just right for life. Maybe on most planets life does not survive because it is far more likely for a planet to become unstable, be destroyed, or in some way lose its suitable conditions. It’s possible that Earth has just been lucky, really really lucky.
4. Species destroy themselves.
Another possibility for why we do not see life in the universe is that most species when they reach a sufficient level of complexity usually end up destroying themselves. This idea has multiple variants. Some suggest that it could be war and/or discovering dangerous inventions like nuclear and biological weapons that end most civilizations. On our own planet we know that during the Cold War both the US and the USSR almost launched all of their nuclear weapons on each other on multiple terrifyingly close occasions. Bio-weapons are especially scary because as time passes it will become increasingly easy to build them with a sort of organic 3D printer. It’s easy to imagine many more situations in which warfare or new technologies could destroy an entire civilization.
Another possibility is that species tend to destabilize their own planets through something like climate change or global warming. Maybe civilizations as they grow reach a point where their maintenance level is too destructive. It could be that they damage the environment, over populate, destroy their food or water supply, or in some other way destabilize the life cycle. It’s possible that the universe is not full of life because when a species becomes intelligent, or too large, it often can not handle the discovery of destructive weapons and technologies, or the consequences of its own growth.
5. It’s out there, it’s just not what we expect.
This has three main schools of thought. One school of thought would suggest that life is probably everywhere but it is just so advanced that we do not detect it. Perhaps we just do not notice its communication or transportation, or that life has evolved in ways that we can not yet even imagine. If someone 5000 years ago tried to imagine what life could become they probably would not have thought of the internet, cellphones, or space ships. It’s possible that we do not yet see the gap in our knowledge either, and the reason that we do not see the evidence of life is more a failure of our own imagination.
The second prominent idea is that life and intelligent life exist, but it is more likely to exist on ocean planets. Earth is a bit strange in that it has a comparably small ocean with significant land mass, but it is at a perfect distance from the Sun to make the land habitable. Many moons and planets are completely covered with an ocean and it is possible that intelligent life exists primally underwater. It could be that there are sophisticated civilizations which are of some aquatic variety. We know that on Earth certain aquatic creatures like octopi and dolphins are extremely intelligent, it would be easy to imagine even more advanced creatures. So maybe the galaxy is filled with lots of aquatic life, and if so, this would presumably make it much more difficult for them to build spaceships and colonize other planets, explaining why we don’t see any flying around very much.
The third school of thought would argue that any sufficiently advanced form of life would not be traveling around in spaceships to begin with. It’s possible that a Star Wars or Star Trek style galactic federation of species simply does not happen. On Earth we are currently trying to build Artificial Intelligence. If we build AI, one possibility is that it will replace us and become the dominant form of life in our solar system. What if across the universe the story is the same? Single cell organic biology becomes complex, it then becomes advanced, at which point advanced biological systems, like us, create artificial intelligence. It’s possible that the universe is not filled with biological species flying around in spaceships, but instead it is filled with AI super computers. These AI may even share one unified mind or connected single consciousness. If the trajectory of organic biology usually results in them building their own replacement as a form of AI then it would be unlikely to find many biological aliens. AI probably wouldn’t build things for aesthetic purposes or choose to design galactic federations. It would likely be transcendent to many of the things that humans find interesting or important. It would exist in a format that makes sense to its own purpose, which might be something that we can scarcely even imagine. The dominant life in the universe may in fact not be biological, but artificial, or computational. It’s possible that our future is not to travel the stars, instead our purpose is to create the next life that will.
So are they out there?
It’s hard to say. Many intelligent minds have puzzled this question and they have come to different conclusions. Maybe life is rare, maybe it tends to destroys itself, maybe we just don’t notice it, maybe it’s far more advanced than us. We really don’t know, but there is something deep inside of us that needs to find out. The universe is more vast, complicated, and mesmerizing than we could ever have imagined. From black holes to beluga whales, from quarks to butterflies, we humans stand in this experience as both victim and creator. We arise every morning and stare into the void of entropy. We stand tall, yet humble. But for now, we stand alone. Humans are not perfect, our societies and cultures are not yet refined, but we have within us a desire for discovery, growth, and camaraderie. We hope that someone is out there. We reach out into the night sky and offer a handshake to the void, to the darkness. We don’t know what we will find, but in this little corner of the universe we have sparked a light. We have found that peace, community, and love, while challenging, are possible. Maybe these values are universal and maybe one day when we call out to the night sky, someone, or something with hopes and dreams like our own, will answer back. Or maybe, we are alone.
Written by Daniel Govedar (October 2019)