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(Previous Page): Part 6: The Principle of Plenitude 


The Goldilocks Enigma


      The Principle of Plenitude, which states that the vast amount of stars and planets in the universe gives a higher probability that events with a slight chance of occurring eventually will, is an argument for the formation of life on other planets. While the Principle of Plenitude surely helps bolster any pluralistic argument, it is not by itself a powerful enough argument to be irrefutable in the argument for extraterrestrial life. The Goldilocks Enigma, the anti-pluralistic equivalent, is also inherently impossible to refute. The Goldilocks Enigma comes from scientific observations showing that if the universe or the planet Earth were different, the possibility for the formation of life would quickly diminish.  It is commonly known as the Goldilocks Enigma because many fundamental constants of the universe were "just right," similar to the porridge that Goldilocks ate in the fairy tale. Many authors, such as William WhewellAlfred Russel Wallace and Stephen Webb, have written about how unique our place in the universe must be. They have all argued, more or less, that it shows how special life is and that we are most likely alone. The Goldilocks Enigma is a way to check pluralistic enthusiasm by putting scientific and astronomical findings in the context of the formation of life and negates the Principle of Plentitude. This duality has certainly been consistent throughout the history of the extraterrestrial life debate: regardless of the number of valid arguments for one side or the other, belief in extraterrestrial life ultimately comes down to one's own opinions and worldview.


     The first example of the belief that Earth was unique came from Aristotle in about 300 B.C. He argued that the universe rotated around the Earth, which was made out of a different material than the rest of the universe.  His universe was finite and stopped at the end of the solar system.  Aristotle believed that all matter had a natural tendency to fall towards the center of the Universe, and because things fell toward the center of the Earth, we must be at that center. Because Aristotle placed significance on the Earth and claimed that a deity moved the universe, his theories were popular with philosophers and the Christian Church. His theories were not pushed aside by Copernicus in the sixteenth century.  While science ultimately caused us to throw out Aristotle's ideas, his principles were logically consistent and thus lasted for over a century and a half.


     In the mid-nineteenth century, William Whewell revived the idea that the Earth was special.  He began by arguing against many writers who were asking why the Earth should be different from other planets by turning the question around, asking, "Why shouldn't the Earth be special?" Whewell believed that the Earth was in a unique position in our universe: 

And thus, all these Phenomena concur in making it appear probable, that the Earth is placed in that region of the solar system in which the planet-forming powers are most vigorous and potent; between the region of permanent nebulous vapor, and the region of mere shreds and specks of planetary matter, such as are the satellites and the planetoidal group (Whewell, p. 23).

He continued by arguing that the Earth was in the "temperate zone" (Whewell Ch. 10) of the solar system.  Whewell argued that the Earth was in just the right spot in the solar system to enjoy the warmth of the Sun while not being burned by it.  He wrote that

The Earth is really the domestic hearth of the Solar System; adjusted between the hot and fiery haze on one side, the cold and watery vapor on the other.  This region only is fit to be a domestic hearth, a seat of habitation; and in this region is placed the largest solid globe of our system; and on this globe, by a series of creative operations, entirely different from any of those which separated the solid from the vaporous, the cold from the hot, the moist from the dry, have been established, in succession, plants, and animals, and man (Whewell pg. 23). 

Earth was not too cold nor too warm (think of the Goldilocks story).  Whewell also used nature to argue that not every part of existence has to support life and since we have only observed life on Earth it must follow that Earth might be the only life-bearing planet.


     Alfred Russel Wallace also contemplated the Goldilocks Enigma in his 1903 book Man's Place in the Universe. In his book, Wallace wrote that 

"All the evidence at our command goes to assure us that our earth alone in the Solar System has been from its very origin adapted to be the theatre for the development of organized and intelligent life.  Our position within that system is, therefore, as central and unique as that of our Sun in the whole stellar universe" (Wallace pg. 409).

Similar to Whewell, Wallace argued that the Earth was placed in such a way that it was just warm enough to form life but not so warm as to make life impossible.  He believed that the atmosphere on Earth was very different from those on other planets because it was capable of producing a circulation of gases that fueled the water cycle.  He also placed a large emphasis on the ocean, claiming that the tides were essential in maintaining the temperature of the Earth.  The depths of the Earth’s oceans are also important because they suggest that the presence of water is permanent, meaning that Earth is unlikely dry up, as other planets seem to have.  Wallace pointed out that even the levels of atmospheric dust are important since they give water something to form on in our atmosphere.  In this light, even the Earth's deserts and other dry areas are important because they supply the dust that is essential in the precipitation phase of the water cycle.  Finally, Whewell argued that the Earth must be in the center of the Milky Way because there is an even distribution of stars surrounding us and because the weak gravity on the edges of the galaxy would make life unlikely due to the possibility of planets flying off into the void of dark space.


     Another man to discuss the "perfect placement" of the Earth in the galaxy was paleontologist Peter Ward. He was recently interviewed, and discussed the Earth's seemingly ideal real-estate position. He said that if Earth was any closer or any further from the sun, life would most likely not have emerged here. In addition, he speaks of the universe being a very dangerous place and because of our position in relation to Jupiter, the gas giant; we are hit by fewer meteorites than many other planets are. He says that our positions like ours are so rare in the universe that he predicts life only once at most per galaxy.


     Stephen Webb also briefly looked at the Goldilocks Enigma in his book "Where is Everybody?" in which he discussed possible answers to the Fermi Paradox.  He referenced the possibility that the habitable zones of the universe might not exist long enough to produce life.  We know that life took a very long time to emerge on Earth and it might take just as long on other planets.  If a super nova wipes out the habitable zones of the universe or an asteroid hits a planet, life may not have enough time to develop fully.  He continued by stressing the importance of Jupiter in our solar system.  He argued that Jupiter's uniquely elliptical orbit and immense gravity help to maintain the orbits of other celestial bodies.  Other systems may not have a planet that can cover all of the jobs that Jupiter can accomplish making it difficult for life to form on a planet.  Finally, plate tectonics form the continents on Earth replenish the crust, help maintain a constant temperature and produce the magnetic field that protects the Earth from dangerous solar radiation but scientists cannot be sure if other planets have plate tectonics. 


     This paper only looks at a few writers who have argued for the Goldilocks Enigma but the list continues. The Goldilocks Enigma as argued by Whewell and Wallace was one of the first logically convincing arguments against plurality, particularly one that addresses the Principle of Plenitude.  As science advances, it shows how unique the Earth is, ironically supporting a concept that was generally ruled out hundreds of years ago.  The Goldilocks Enigma has proven resilient because the implications of such a theory are straightforward. If the Earth were the only planet in the right zone, with the right solar system and the right geological makeup, then it would rule out the idea that there could be life forming or had formed elsewhere. The belief that the Earth is unique and special in this capacity would mean that humans are the only intelligent life in the galaxy. However, even though Earth is more special than we thought, we do not know that it is unique.



(Next Page): Final Essay Conclusion

Book Review For Paul Davies'The Goldilocks Enigma:


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