Recently I read that some scientists think that there may be
planets more suitable to life than Earth. How does this relate to the Fermi
Paradox?
What is the Fermi
Paradox?
The Fermi Paradox comes from a question that the physicist
Enrico Fermi asked during a discussion of flying saucers in the late 1940s. https://en.wikipedia.org/wiki/Fermi_paradox
When you consider the age of the Universe, it seems likely
that civilizations should have developed on other planets. If so, they should
have been able to colonize the entire galaxy by now. Since we see no evidence
of aliens, the question we need to ask is "where are they?"
Over the years since then, scientists have come up with a
variety of solutions to this question. If there are super habitable planets,
how can we explain this paradox?
What is a Super
Habitable Planet?
René Heller and John Armstrong suggest that many exo-planets
may be more conducive to life than Earth.
(see: https://en.wikipedia.org/wiki/Superhabitable_planet)
Briefly, a super habitable planet would be larger than Earth and orbit a
smaller, and cooler, star.
Heller and Armstrong suggested that a planet about twice the
mass of Earth would be the most suitable for life. The larger size would help
maintain a thicker and more stable atmosphere for a longer time.
Cooler stars, like orange dwarf and red dwarf stars, are
much more common that yellow dwarf stars like the Sun. The habitable zone
around these star would be stable for longer periods. This would allow more
time for life to develop and evolve on a planet in the habitable zone.
There is a lot of room for debate about the habitability of
planets. For this post, I will accept these ideas.
Civilizations on
Super Habitable Planets
If super habitable planets are common, then why do we se no
evidence of them? I think it may be that conditions on these planets make it
more difficult for advanced civilizations to develop the technology to explore
space.
Michael Chorost in his article "Do Super-Earths Trap
the Civilizations On Them?" considers the possibility that the higher
gravity and the required escape velocity would make it harder to reach space.
(see https://cdn.psychologytoday.com/blog/world-wide-mind/201211/do-super-earths-trap-the-civilizations-them).
He concludes that these limitations would not stop development of space travel.
I think he is too optimistic and that the additional effort may make it
unlikely that these civilizations would explore beyond their own planet.
A second explanation is that civilizations on super-earths
may not be aware of space. These planets would have deeper and thicker
atmospheres, which would limit their ability to see the stars and other planets
in the sky. This would be particularly true of planets around smaller stars. These
planets will become tidally locked and life could only survive in a narrow
twilight band around the planet. The thick atmosphere and the brighter sky
would prevent them from seeing the stars.
Lonely Planets
Another possibility would be planets that are the only
sizable body in a solar system. Without an nearby destination, like the Moon
and Mars for Earth, there would be no easy first steps. Also, without other
planets, the imaginations of civilizations on these planets could not develop a
science fiction literature about travel to other planets. With out this
fantasy, there would be less drive to develop space technology.
Summary
One possible explanation of the Fermi Paradox is that most
civilizations on habitable planets are unable to develop space technology. This
may be due to the limits imposed by the nature of super habitable planets on
the ability to reach space. The nature of these planets may also limit the
ability of these civilizations to even conceive of the idea of travel beyond
their own planet.
Earth may be rare, in that it is large enough for a
technological civilization to develop, but is also small enough that space
travel is relatively easy to develop.
This post is a mirror from my main blog http://www.dynamiclethargyfilms.ca/blog
