Space is big. Astronomers are still trying to wrap their minds around the size and complexity of our universe. Here on Earth, there is intelligent life. We have the capacity to look out at the stars, think abstractly, make choices and improve ourselves.
Anybody who has spent even a small amount of time thinking about space has wondered about the possibility of intelligent life. Space seems so large that it is shocking that we have not found any evidence of extraterrestrial civilizations out there. This is known as Fermi’s Paradox. When considering the vastness of space, that it seems so empty is mind boggling.
Here are four reasons why Fermi’s Paradox exists. There are many more, but these are my favorites.
1. The Earth is really rare
When we watch shows like Star Trek, viewers are conditioned to expect the universe to be teeming with habitable planets, stable environments, and thriving species. But what if that is not the case? What if a habitable planet like our Earth is extremely rare? The theory that our Earth is a unique case in the galaxy is known as the Rare Earth Hypothesis.
Scientists who believe this theory reason that a possible reason that we have no found intelligent alien life is that intelligent life is rare in the galaxy. Even though there are an estimated 8.8 million Earth like planets in the galaxy, these would all have to be within the habitable zone to sustain life. In the off-chance that all 8.8 million planets had life on them, that would still be small part of our galaxy compared to the 100 billion stars that are in the Milky Way.
It is important to remember that the Rare Earth hypothesis only accounts for intelligent life. Bacteria and other single-celled organisms may be common, but not intelligent. We can look at our solar system as an example of how rare complex life is. Our system has many places that could support life (Mars, Enceladus, Titan, Europa) but all have significant disadvantages that would keep complex life from developing. It is possible that our atmospheric conditions, temperature, geologic conditions and many other factors are uncommon in the galaxy. Looking for intelligent life is like looking for a needle in a haystack.
2. Our Earth is really boring
Humans have a pretty inflated view of themselves. When we talk about being visited by extraterrestrial life, we act like they actually want to visit us, because we are so interesting. I mean, we have bendable iPhones, social networking sites, and dollar menu hamburgers. What is not to love?
How exciting is the Earth? Unfortunately, science has not developed a mathematical scale to find how interesting/exciting a planet is. But we do have the Kardashev scale.
Soviet astronomer Nikolai Kardashev proposed the scale back in 1964. The scale measures the amount of energy available and used by a civilization and predicts the technological level of that civilization. Of course, the scale is hypothetical, since we do not have any other civilizations to compare to. But it is instructive. Here are the types of civilizations:
- Type 1: This civilization would have access to the equivalent energy of the planet Earth. A civilization at this level would be using advanced energy sources such as solar power or anti-matter. A type 1 civilization would be capable of interstellar travel, but in a very limited degree.
- Type 2: A civilization at this level would be able to spread their technology to multiple planets and solar systems. Type 2 civilizations would have the technological ability to capture the energy of stars and construct massive engineering feats like a Dyson Sphere. Insterstellar travel would reach a practical level, allowing planetary systems to be connected. An example of this civilization would be the United Federation of Planets in Star Trek.
- Type 3: A Type 3 civilization would use the available power of the galaxy. They would be able to use the energy of stars and exotic energy sources such as black holes and gamma ray bursts. Interstellar travel would be common place, and practical for all members of the civilization. The Galactic Empire in Star Wars is an example of a Type 3 civilization.
Where is the Earth in this scale? Well, we have not even made it to Type 1 level. In 1973 we were estimated to be at a 0.7. In 2014 we may be at a higher level, but only barely so.
If you had the capability to travel to any star, would you travel to Earth? If interstellar civilizations are possible, it is more likely that they would spend time with other civilizations than with our relatively primitive Earth. Think about it. How many adults do you know that prefer to hang out with third graders over people of their own mental capacity? For a civilization capable of space travel, we may just be too boring.
3. We can not recognize their signals
Even if there are many habitable planets in our galaxy, and they actually want to talk to us, would we actually be able to recognize their signals?
Linguistics is a challenging field. Translating Earth languages into each other is a complex and intensive process. Professional linguists go through years and years of schooling to master one language, and usually a few others. And this is for languages that are found on Earth. Even though many cultures exist on Earth, we have many linguistic and cultural similarities. Imagine having to translate an alien language into something that we could understand.
In the Star Trek: The Next Generation episode “Darmok” the difficulty of translating alien languages is explored. Picard and the crew of the Enterprise make contact with the Tamarians, a species that has gained a reputation as being understandable. Even though Universal Translators are common in the Star Trek universe, nobody can understand the Tamarians. When Picard first speaks to a Tamarian, we hear the aliens words in English, but they do not make any sense. Eventually Picard realizes that the Tamarians speak in metaphor so that a phrase like: “Darmok and Jalad at Tanagra” means to cooperate. The crew of the Enterprise is finally able to understand the Tamarians.
Imagine having to recognize an alien language even without the help of a Universal Translator that will render the words in English. If we ever got a message, the cultural gap would be so large that it might be impossible to ever understand what the aliens are saying. That is considering that we even recognize the signal when we get it. An alien race would be using technology different from ours, making it very unlikely that we would actually end up recognize their signals when we received it. Alien civilizations may be staring us right in the face, we just are not able to recognize them. Think about that next time you hear static on the radio.
4. Advanced civilizations hit a stumbling block
Many scientists find the Rare Earth hypothesis discussed above to be unlikely. The vastness of our galaxy and the universe makes it statistically likely that there are countless habitable worlds out there. We need another reason to explain their absence.
In the past few decades a theory has been catching on that advanced civilizations inevitably will hit a stumbling block in their path to interstellar travel. As a civilization develops more technology and energy output, it begins to be at greater risk of destroying itself or being destroyed by natural phenomenon.
Look at Earth history for an example. Just as we were completing our first space missions in the 1960’s, the world was engulfed by the Cold War. Events such as the Cuban Missile Crisis and the Vietnam War could have easily triggered a chain of events that would have destroyed human life. The same technology that allowed us to explore space at that time also gave us the capability of Mutually Assured Destruction. Fortunately, we were able to avoid confrontation. But we are not safe yet. Even today, many nations have nuclear capability and our industrialization is leading the world into dramatic climate change.
The human race has been lucky up to this point, but many other civilizations probably have not been. Imagine how many civilizations were destroyed just as they were developing nuclear power or how many were wiped out by natural disasters. There may be even greater dangers in the future as humanity develops more complex technology and increases our amount of available power. In the vastness of the galaxy, many civilizations have most likely been destroyed in their pursuit of worthy goals.
As we look out at the stars, the perceived emptiness of the cosmos may just be an illusion, or it may be that we are a very unique planet, like a oasis in the desert. Whatever the case, if we ever find intelligent extraterrestrial life, it will be the most important discovery that our world has ever seen.