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22 Twentieth-century astronomers, by revealing the unsuspected vastness of the universe, displaced us even farther from a central position. Harlow Shapley reported in 1918 that our solar system is at the periphery of the Milky Way galaxy. By 1924, Edwin Hubble had shown that there are many other galaxies, each containing multitudes of stars. Meanwhile, Einstein’s theories denied the existence of any fixed point or any absolute space in the universe; the cosmos has no center.*® mm: . ° 1 cou 4 a wat This enormous extension of scale powerfully strengthened the argu- ment from probability. These advances in astronomy, declared science historian Steven Dick, destroyed the argument for an anthropocentric universe.” Human life and history were dwarfed by the immensity of geological and biological time. As McNeill put it, astronomers coolly presumed the forma- tion and snuffing out of innumerable stars, casually assumed the existence of other solar systems in all stages of formation and dissolution, asserted without qualm the indefinite reduplication of the galaxy, and speculated freely on superorderings of galaxies.” Despite these findings, the plurality of worlds suffered a temporary setback when the nebular theory for the origin of our solar system was overtaken by another proposal. In the new model, the formation of planets depended on rare close encounters between two stars. British astronomer James Jeans, a leading advocate of this concept, argued that our solar system seemed to be very exceptional. Astronomy, he wrote in 1923, “begins to whisper that life must necessarily be somewhat rare” in the universe.” Although we humans no longer could think of ourselves as central, we still could think of ourselves as unique. In the meantime, improving observations discredited the idea of an advanced civilization on Mars. Lowell’s theory ultimately failed the Galilean test; the straight lines had been an illusion, a product of the human hunger for recognizable patterns. Other research showed that Mars was a frigid desert. If any life existed there, it might be limited to simple, hardy forms such as lichens. A few scientists claimed to have detected spectroscopic evidence of plant life, but most rejected or ignored those findings. The search for extraterrestrials became so burdened with a “giggle factor” that many astronomers turned away from studies of Mars and the question of intelligent aliens. “The revulsion at this miscarriage of the sci- entific enterprise brought discredit not just to planetary science,” wrote astronomer Frank Drake later, “but to the whole idea that there might be life elsewhere in space.” a ne eee te ee ee Ld eet de Too many astronomers had tried to resolve a problem beyond the limits of the science of their time. This frustration still may be with us today as we search for signals from more distant civilizations. A Belief in Other Minds Expansion and Skepticism