Fermi's Paradox is the paradox that we have not yet observed extraterrestrials, even though there seems to be abundant places in our galaxy where life could evolve. A recent study suggests that one out of every five sunlike stars may have a planet like Earth. But if there are so many extraterrestrial civilizations out there, why haven't some of them come here already, and taken over our planet, or at least made themselves known?
I think it is fallacious to use Fermi's Paradox as a basis for concluding that man is alone in the universe, as I argued in my previous post 12 Reasons Why Fermi's Paradox Does Not Show We Are Alone. One possible explanation for Fermi's Paradox is known as the Zoo Hypothesis. This is the idea that extraterrestrials know about our existence, but are deliberately leaving us alone to go our own way, at least for the time being. The idea is favored by believers in UFOs, who might tend to believe that UFOs are visitors who take a peek at humanity rather like zoo visitors who occasionally pass by and take a peek inside the cage of a zoo.
There is another possibility similar to the Zoo Hypothesis, but somewhat larger in scope. This idea is what I may call the Cosmic Wildlife Reserve hypothesis. This is the hypothesis that Earth is within a certain portion of the galaxy that has been declared as “off limits” to colonization from external planets – an area consisting of multiple solar systems.
Is the idea of a cosmic wildlife reserve reasonable? Based on our earthly experience, it would seem that it is. We know that on our planet great nations have set apart significant parts of their land and designated it as national parks or wildlife reserves or national forests, where the building of things like apartment buildings, factories, and shopping malls are forbidden. In the United States this has been done through the creation of the National Park system, the establishment of state forests, and the establishment of wildlife reserves such as the Arctic National Wildlife Refuge. The same thing has been done in Australia, where a significant fraction of the land has been set aside as part of a National Reserve.
Imagine if millions of years ago a particular civilization developed starships capable of interstellar travel. It might then set out to colonize as much of the galaxy as it could, a task that might take millions of years. But there is no reason to think that it would greedily gobble up every available planet for its colonies. There would probably be an environmental backlash against the despoiling of nature that would occur under such a colonization program. Some would argue: surely we should leave a fraction of the galaxy in its natural state, for the sake of cosmic biological diversity, and to allow future generations to have their own chance to explore or colonize natural, unspoiled planets. It might then occur that certain parts of the galaxy might be designated as cosmic wildlife areas, off limits to interstellar colonizers.
But is there any way to test the fascinating hypothesis that Earth is part of such a cosmic wildlife reserve? There might be. It might be possible to get evidence for such a hypothesis by doing a kind of “sector analysis” in which we compare the characteristics of different areas of the galaxy, including the area surrounding our sun.
To test this Cosmic Wildlife Reserve hypothesis, we could take the following approach:
- Gather data about various astronomical characteristics of the solar systems nearby our sun.
- Gather data about various astronomical characteristics of not-very-close solar systems a few hundred light years from our sun.
- See whether the solar systems a few hundred light years far from our sun have characteristics significantly different from the solar systems near our sun-- differences that might be due to the fact that such systems have been colonized, while solar systems close to ours have not been colonized.
Here is one type of survey that could be done along these lines:
- We gather data about the average amount of infrared radiation coming from solar systems near the sun.
- We gather data about the average amount of infrared radiation coming from not-very-close solar systems a few hundred light years far from the sun.
- We analyze whether the average amount of infrared radiation coming from solar systems near the sun is significantly lower than the average amount of infrared radiation coming from not-very-close solar systems a few hundred light years far from the sun.
Why bother analyzing infrared radiation for this purpose? Infrared radiation is given off by hot objects. Once a solar system had been colonized by a super-advanced civilization, it might be giving off more infrared radiation than a solar system that had not been colonized. There might be all kinds of space colonies and rockets and orbiting solar power stations that might cause a previously colonized solar system to give off more infrared radiation, particularly if it were inhabited by a civilization vastly more advanced than ours.
It is just possible that this type of “sector analysis” (using infrared radiation or some other physical characteristic) might lead us to conclude that the area around our solar system is a little different from other areas a little farther away. In such a case we might have reason to suspect that we are part of an area of the galaxy that has been declared “off limits,” similar to the way the Arctic National Wildlife Refuge has been declared “off limits.”
Is Earth a forbidden planet?