The summer 2020 issue of I-M Intelligent Magazine…
… includes “an exercise in fun speculation” by me on a potential link between solar eclipses and the Fermi paradox.
According to the Copernican principle, there is nothing special about the earth’s place in the universe. Except for the awkward fact that — on current evidence — it’s the only place in the universe to have produced an intelligent and curious species capable of reaching beyond its home planet. In the words of the revered physicist Enrico Fermi: where is everybody?
One solution to the paradox is the rare earth hypothesis. This proposes that the development of complex life on our planet depended upon a labyrinthine set of circumstances that may be vanishingly rare within the universe. By chance, everything about the earth is perfectly balanced in terms of physics (eg, its stable orbit), chemistry (eg, its abundance of metals) and biology (eg, the development of photosynthesis).
In my article for I-M, I’ve taken the rare earth hypothesis one step further:
Does the earth have some unique ingredient that enabled not only the development of complex life, but also the development of intelligent and curious life? After all, it is not biological complexity per se that has led to humans reaching beyond our home planet, or pondering questions such as “where is everybody?”
We live in a world of routine processes: sunrises and sunsets, tides and seasons, predators and prey. (Even earthquakes and volcanoes are routine events in many parts of the world.) But, as the philosopher and cognitive scientist Daniel C Dennett points out, “too much regularity in the selective environment can be a trap.” In an environment where novelty remains below a certain threshold, brains may never receive the stimuli they require to develop human-like levels of curiosity.
A solar eclipse, on the other hand, is anything but routine. There is no warning or preamble; it comes — literally — out of a clear blue sky. Given that even modern-day observers can be overwhelmed by an eclipse, the sun’s sudden disappearance must have created an unparalleled cognitive crisis for our ancestors.
Could total and annular eclipses have acted as a pump of curiosity for early humans? Crucially, they occur at what might be an ideal frequency. If they occurred more frequently, they would have become routine events, and not provided sufficient novelty to stimulate the brain. If they occurred less frequently, they would not have provided enough stimuli to different communities, at different times, to kindle the first flames of human curiosity.
The frequency of solar eclipses — plus the scale of their impact on humans — depends upon two coincidences:
(1) The ratio of the moon’s and the sun’s diameters is the same as the ratio of their distances. This means that, although their actual sizes are two orders of magnitude different, the moon and the sun are the same size in our sky
(2) The moon’s orbit is tilted, which means the earth, moon and sun do not fall into alignment every month.
If such a combination of coincidences is rare within the cosmos, the pump of curiosity could be a solution to the Fermi paradox. Perhaps we are the only species in the universe to ask “where is everybody?”
Note: I’m grateful to Stephen Webb (the author of Where is everybody? Seventy-five solutions to the Fermi paradox and the problem of extraterrestrial life), John G Cramer (who proposed a Fermi paradox solution called the pump of evolution in the 1980s) and Daniel C Dennett (the above quote appeared in From bacteria to Bach and back: The evolution of minds) for their comments on a previous version of this article.