The Fermi Paradox: Too Rare? IV

I have completed this list:

  1. Stars I
  2. Planets I
  3. Origin of Life I
  4. Origin of Photosynthesis II
  5. Multicellularity II
  6. Colonization of Land II
  7. Intelligence III
  8. Technology III
  9. Abstract Science III

There is an additional set of issues that I wish to discuss before I turn to other Fermi-paradox solutions.

  1. Natural Disasters
  2. Self-Destruction

So after looking at all these factors, I conclude that there are numerous possible bottlenecks that can prevent the emergence of a long-lived technological civilization, and numerous possible calamities that have been nicknamed “The Great Filter”. So rarity is very hard to rule out.

Natural Disasters

The history of our planet’s biota has had several mass extinctions. The best-known one is the K-T or K-Pg one, the one where an asteroid killed off the (non-avian) dinosaurs. But there was a big one at the end of the Permian period, some 160 million years before. It was bigger, but it is less well-known, likely because trilobites are less spectacular than dinosaurs.

There are several proposed causes, like asteroid and comet impacts, massive flood-basalt volcanic eruptions, supernovae, gamma-ray bursts, sea-level falls, bouts of global warming or global cooling, etc. None of these causes are specific to the Earth, and biotas elsewhere in the Universe could also have suffered mass extinctions.

But if a sentient species emerges, it could keep at least some of these disasters from happening, like keeping asteroids from hitting their homeworlds.


This became a rather obvious issue after the development of nuclear bombs. The horrors of World Wars I and II combined with nuclear bombs seemed to indicate that a nuclear-bomb World War III had a strong risk of happening. But so far, we have dodged that bullet, though with some close calls.

Here are some possible ways of self-destruction:

  • War
  • Environmental Problems
  • Resource Depletion
  • Disease
  • Social / Political / Economic Collapse
  • Technological Failure
  • Loss of Interest

Environmental problems could be something like global warming. Resource depletion could be something like consumption of fossil fuels without devising renewable substitutes. Disease could be some genetically-engineered organism developed as a weapon, but one that gets out of control. Social / political / economic collapses have happened several times over humanity’s recorded history, most notably in the Western Roman Empire.

Technological failures could include such things as the Great Internet Worm of 1988, some software that reproduced itself and spread itself by exploiting software vulnerabilities. It took several days to expunge this software from the numerous servers that it had infected. It also includes such scenarios as nanomachines multiplying out of control and turning much of their homeworld’s surface into “gray goo”.

It is also possible that the inhabitants of some technological civilization prefer to revert to some earlier and presumably more pleasant state of technology. Thus being like the Ba’ku in Star Trek: Insurrection. But in the experience of humanity, while many people have romanticized various presumably simpler societies, they have seldom attempted to create such societies for themselves. The Amish, who continue to use 18th and 19th century technology, remain a minority.

It is difficult to assess how common these scenarios might be. Most of them depend on details of the civilizations, details which may differ dramatically.

So I end my discussion of possible causes of the rarity of interstellar-capable technological civilizations.


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