In reality, Hubble's discoveries did not arrive in one eureka moment, but only after years of contentious debates over conjectures and measurements that were fiercely disputed. That was one reason for my interest in delving more deeply into this story, a rich saga published in my latest book The Day We Found the Universe. It shows how the avenue of science is more often filled with twists, turns, and detours than unobstructed straightaways.
Here are some surprises to be found within the book's pages:
- Hubble didn’t really discover the expanding universe: The first person to observe that galaxies were racing away from us was Vesto Slipher at the Lowell Observatory in Arizona, an astronomer now largely forgotten. He first noticed the effect in 1913, sixteen years before Hubble’s historic observations. Slipher didn’t know at the time it was due to a universe expanding, but he did suggest the galaxies might be “scattering” in some way.
- Hubble was a scientific cad: In 1929 Hubble pegged how the galaxies move outward but failed to note in his famous paper that half his data—the velocities—were Vesto Slipher’s measurements. There was no citation, no acknowledgment—a serious breach of scientific protocol. Slipher deserves half the credit. Privately, Slipher was bitter but too humble and reserved to demand his share of the glory.
- The so-called “discoverer” of the expanding universe never liked the idea: For the rest of his life, Hubble had serious doubts about a universe expanding. He told a Los Angeles Times reporter, “It is difficult to believe that the velocities are real—that all matter is actually scattering away from our region of space.” In his scientific papers, he always referred to the galaxies’ “apparent” velocities, worried that a new law of physics might sneak in and change the interpretation.
- A woman made the discovery of the modern universe possible: Henrietta Leavitt, working at the Harvard College Observatory, came upon astronomy’s celestial Rosetta Stone in 1912, which allowed Edwin Hubble twelve years later to prove that the Milky Way was not alone but just one of a multitude of galaxies. She found a new cosmic yardstick, based on blinking stars called Cepheid variables, to determine distances to far-off celestial objects, a task that was formerly impossible to carry out. She might have earned a Nobel prize for this work, if she had not died of stomach cancer at the age of 53.
- Edwin Hubble was not much liked by his colleagues: Hubble, often arrogant and standoffish, rarely hung out with his fellow astronomers. One called him a “stuffed shirt.” Hubble preferred to socialize with the actors and writers in nearby Hollywood, the aristocrats of southern California. While a Rhodes scholar at Oxford University, he completely reinvented himself: he adopted a British accent that he maintained for the rest of his life, dressed like a dandy, and began to add dubious credentials to his résumé (like saying he once practiced law, which he never did). Hubble’s affectation for wearing jodhpurs, leather puttees, and a beret while observing, or going around and saying “Bah Jove,” was simply too much for the other astronomers to bear.
- Not Hubble, not Einstein, but a Belgian priest first discovered how the cosmos truly operates: Both a theorist and a Jesuit priest, Georges Lemaître predicted in 1927—two years before Hubble measured it—that space-time was moving outward, with the galaxies going along for the ride. Here was the reason for Slipher's fleeing galaxies. Lemaître even estimated a rate of expansion close to the one that Hubble would later calculate. Since the young priest published this astonishing news in an obscure journal, no one noticed—no one at all.
- The Hubble Space Telescope could have had another name: Three men had a good chance at proving the universe was filled with other galaxies, beyond the borders of the Milky Way, years before Hubble. Each had the opportunity and the expertise. But James Keeler at the Lick Observatory prematurely died in 1900 at the age of 42; Heber Curtis, also at Lick, took a promotion, taking himself out of the race; and Harvard astronomer Harlow Shapley was mulishly wedded to a flawed vision of the cosmos, a blunder he regretted for the rest of his life.