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?
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