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24 Life but waits in the wings of existence for its cue, to enter the scene the moment the stage is set. The long debate about inhabited worlds had taken another turn by the 1940s. Astronomers found that smaller, cooler stars were rotating more slowly than expected, suggesting that some of their angular momentum had been transferred to planets. By 1958, the idea of numerous planetary systems had regained scientific credibility.” Meanwhile, early research into the origins of life on Earth had strength- ened the idea that living things were a natural product of physical and chemical evolution. Russian biochemist Aleksandr Oparin contended in 1924 that there was no fundamental difference between a living organism and lifeless matter; the complex combinations and properties of life must have arisen in the process of physical evolution. British biochemist J.B.S. Haldane independently published similar ideas, describing how the action of ultraviolet light on the Earth’s primitive atmosphere might have formed a “primordial soup.”*” Other scientists began testing these concepts with experiments, finding that precursors to living matter are surprisingly easy to make. Stanley Miller proved in the 1950s that trace quantities of organic compounds that are life’s building blocks could be formed through the action of electric discharges and ultraviolet light on the probable constituents of Earth’s early atmosphere. If such an evolution happened on the Earth, it might occur elsewhere as well. Harvard biologist George Wald proclaimed that the Oparin—Haldane process would be an inevitable event on any planet similar to the Earth in size and temperature. Astronomer Otto Struve, who played a significant early role in support- ing the scientific search for extraterrestrial intelligence, argued in 1955 that life is an intrinsic and inseparable property of certain aggregates of very complex organic molecules. Most sun like stars have planetary systems, he believed; the total number of planets with some form of life could be in the billions.” Three years later, Shapley told us that “whenever the physics, chemistry and climates are right on a planet’s surface, life will emerge, persist, and evolve.” He reasoned that there could be millions of opportunities for life, including at least 100,000 life-bearing planets in our galaxy.” Amid all of this optimism about life, there was a psychic cost as science increasingly excluded metaphysical considerations. In Shapley’s words, Man was exposed as a recent and perhaps ephemeral manifestation in the unrolling of cosmic time.” Under the scrutiny of science, our own species became peripheral. That provoked a strong reaction, one that was to become increasingly visible after 1970. A Belief in Other Minds Ubiquitous Life —Percival Lowell, 1908