Cosmos

The very vastness and richness of the cosmos can make human concerns seem small in comparison. Earth’s existence cannot be called typical either because by far the greatest percentage of the cosmos is made up of emptiness. Nonetheless, there are some hundred million galaxies, each containing billions of stars, any one of which could “be a sun to someone” (5). Thus, it far more likely that among all those galaxies, stars, and accompanying planets, the cosmos is “brimming over with life” (7) than that life is limited to our small rock, the Earth.

Astronomical studies at the time of the publication of Cosmos were largely limited to the local group of galaxies. Even this comparatively small set of about 20 galaxies spans light years and contains dozens of different types of stars, double stars (orbiting each other), and dense star clusters. Only on our own small planet do we know for certain that the study of the cosmos has been developing. Human beings, themselves born of the stars, conduct that study. While that study began with the ancients and continued through the great sea explorers who started to shape our understanding of our planet, we now know that the cosmos is far older and vaster than they could have ever imagined.

What are the possibilities of life elsewhere and would it resemble or originate in the same manner as life on the Earth? Life elsewhere seems a cosmic inevitability given the vastness of even the Milky Way galaxy, which contains billions of planets. Would life on some of those planets evolve the simplest of forms, arise and die out, or perhaps result in intelligences and civilizations more advanced than our own? While all life on Earth is closely related, that has resulted from the life forms adapting to the environment via the process evolution, not due to any particular characteristics of the Earth’s environment. In fact, the similarities of life forms on Earth actually limit biologists’ knowledge.

The story of the Japanese samurai clan the Heike and their war with a second clan, the Genji, in the 12th century shows how humans can affect evolution. The Heike clan was nearly destroyed in a decisive naval battle won by the Genji, so a legend arose that Heike survivors wandered the sea as crabs. The legend persists in part due to a particular crab with a shell marking that resembles a samurai face. These crabs are released after they’re caught instead of being eaten, creating an evolutionary process giving this crab type an advantage. The legend has thus led to artificial selection (instead of natural selection), resulting in many crabs with markings closely resembling a samurai face surviving and thriving. Similarly, domestication produces another form of imposed artificial selection, with species from dairy cows to large ears of corn completely different from their original wild forms due to human preferences and choices.

These examples of accelerated artificial selection are also proof of the corresponding but slower process of natural selection associated with 19th-century naturalists Charles Darwin and Alfred Russel Wallace. Evolution is fact, not theory. Mutations among species make them more or less likely to survive, and natural selection creates the proliferation over time of those with advantage-giving mutations.

A controversy has been produced by the contrasting ideas of evolution and the “Great Designer” theories (21st-century readers would know these false theories by their new term, “Intelligent Design”). While fossil evidence of extinctions could be consistent with the idea of a Great Designer who became dissatisfied with some species, this idea is “disconcerting” (29) as a Great Designer relying on trial and error does not seem convincing. Instead, the deaths of imperfectly adapted species and the positive or negative mutations over times prove the truth of evolution.

Over four billion years, Earth has evolved from being a “molecular Garden of Eden” (31); its development may either be typical of how life evolves on other worlds, or unique even in the Milky Way galaxy. While life may be inevitable on an Earth-like planet, the Earth itself did not evolve much beyond algae for three billion years, and humans only emerged within the last few million years.

The single cell is a regime as “complex and beautiful as the realm of the galaxies and stars” (35). DNA is wonderfully complex, though the molecular nature of trees and humans as essentially the same. It remains to be seen whether the patterns of life’s development on Earth tell anything about its possible development elsewhere in the cosmos. Whatever its nature, the study of a single instance of any extraterrestrial life form “will deprovincialize biology” (41).

Science is possible on Earth because of patterns and predictability, or laws of nature. Examples include the appearance of the same constellations in the night sky annually or nightly, the moon’s control of tides, the dependability of gravity, and the sun’s control of the seasons. From this last revelation came the pre-scientific idea that if the sun or stars control things such as climate and seasons, they may be controlling individual human lives. Thus rose the pseudo-science of astrology. Modern popular astrology can be traced back to the ancient Greek philosopher Ptolemy. Ptolemy believed that individual behavior patterns, national character, individual stature and complexion, and many other things were controlled by the stars. Unlike the science of astronomy, the pseudo-science of astrology makes claims without provable evidence.

Ptolemy was also an astronomer, who like most people of his time believed that other planets and the sun circle the Earth. This hypothesis helped prevent the advance of astronomy for a millennium, until 15th-century Polish scientist Nicholas Copernicus proposed the hypothesis that the sun rather than the Earth is the center of the universe. The sun-centered versus Earth-centered controversy reached a height in the 16th and 17th centuries. Johannes Kepler, born in Germany in 1571, was a key figure in this controversy. Kepler was deeply religious and embraced Copernicus’s idea of a sun-centered universe with the sun being a metaphor for God. Kepler came up with his own theory that the number of planets, their orbital spacing, and other factors connected them with geometrical shapes and God as a divine geometer.

Kepler was eventually introduced to Danish astronomer Tycho Brahe, born in 1546. Theirs was a very uneasy collaboration during Brahe’s lifetime, with the flamboyant Brahe being the greatest “observational genius” of the era and the devout Kepler the “greatest theoretician” (60). Nonetheless, on his deathbed, Brahe bequeathed his years of very detailed planetary observations to Kepler. Brahe’s observations disproved Kepler’s earlier ideas. Through his study of Brahe’s observations and his own observations, Kepler concluded that the planets move in elliptical orbits around the sun, not the circular ones that had previously been supposed.

The discovery of elliptical orbits became one of three laws Kepler identified that are foundational to modern astronomy: 1) planets move in ellipses, 2) planets sweep out equal areas in equal times, and 3) the squares of the periods of the planets (the time for them to complete one orbit) are proportional to the cubes of their average distance from the sun. Eventually, English physicist Isaac Newton, born in 1643, contributed the laws of inertia and gravity, which complement and confirm Kepler’s. The result was the revelation that fairly simple mathematical laws pervade all of nature.