The Day We Found the Universe (43 page)
Read The Day We Found the Universe Online
Authors: Marcia Bartusiak
But the Big Bang model faced a number of challenges before it could be fully accepted. The biggest hurdle was the estimate of the universe's age, based on early (and incorrect) measurements of the rate of cosmic expansion. Hubble's initial rate, calculated from a relatively small sample of galaxies, suggested that the universe originated just two billion years ago, but astronomers already knew of stars around ten billion years old. Looking closer to home, it was also less than the estimated age of Earth. Geologic evidence at the time indicated that Earth's crust was at least three billion years old, likely more. This paradox posed a dilemma for the model for quite a while. How could Earth possibly be older than the universe?
There were other loose ends. For one, the Milky Way still appeared to be far larger than the other galaxies. The Andromeda galaxy, the closest spiral to us, shared so many features with the Milky Way—the same disk of stars, the same system of globular clusters arranged in a halo around it, the same variable stars blinking on and off—and yet all these objects appeared fainter than those in the Milky Way, based on Hubble's initial distance measurement. More than that, Andromeda was smaller. This greatly bothered astronomers, who were now readily applying the Copernican rule to the entire universe: It is unlikely that we occupy a privileged place in the cosmos.
This puzzle persisted until 1952, just when Hubble's long reign as the emperor of cosmology was coming to an end. Having gone into military work during World War II, Hubble had a lot of catching up to do at the war's end, but ill health prevented him from getting back on top. By then Walter Baade, a gifted observer, was beginning to overshadow Hubble with his revelatory work that at last put the universe (and the Big Bang) in better shape. Using both the 100-inch telescope during the war and later the 200-inch launched in 1948 on Palomar Mountain in California, Baade was able to prove that there were two distinct kinds of Cepheid stars. The Cepheids that Hubble used to determine the distance to Andromeda and other galaxies were actually more luminous than the Cepheids that Shapley used to determine his distances to the globular clusters surrounding the Milky Way. Consequently, Hubble had been underestimating his distances to Andromeda and the other galaxies. Hubble's distances had to be completely reworked. Andromeda, for example, was actually twice as far out, which also meant it was bigger than anyone had perceived and so made it more like the Milky Way's twin. Andromeda wasn't smaller or fainter at all, just more distant than previously thought—and that meant the Milky Way was no longer the special kid on the block. Those who desired nature to be uniform breathed a huge sigh of relief. This adjustment had to be made to all the galaxies then measured, essentially doubling the size and age of the universe. This modification at last took the Big Bang model out from under its cloud. With Hubble's rate of expansion determined more accurately as well, as more and more galaxies were measured, the estimated age of the universe was further increased, which at last allowed enough time for all the stars and planets to form after an explosive birth of space and time.
“Never in all the history of science,” said Willem de Sitter in 1931 at a Boston lecture, “has there been a period when new theories and hypotheses arose, flourished, and were abandoned in so quick succession as in the last fifteen or twenty years.” And perhaps never again will astronomy face such a dramatic shift in its conception of the universe. It took only three short decades—from 1900 to 1930, virtual seconds into our past when weighed against humanity's life span—to make this mind-altering transition. The Milky Way, once the universe's lone inhabitant floating in an ocean of darkness, was suddenly joined by billions of other star-filled islands, arranged outward as far as telescopes could peer. Earth turned out to be less than a speck, the cosmic equivalent of a subatomic particle hovering within an immensity still difficult to grasp. It didn't stop there. Astronomers barely had time to adjust to this astounding celestial vastness when they were faced with the knowledge that spacetime, the universe's very fabric, was expanding in all directions, carrying the galaxies with it. It was a rapid one-two punch from which astronomy is still reeling, as observers and theorists alike try to make sense of all its details: how the Big Bang was ignited, how the myriad galaxies were born and evolve, how (and if) the expansion will end.
James Keeler could not possibly have imagined where his pioneering explorations were going to lead when in 1898 he first walked over to the Crossley reflector, a pip-squeak of a telescope compared to Lick Observatory's grand refractor, and made the simple decision to focus his research on the spiral nebulae. But his observations from Ptolemy Ridge had broad repercussions. He at last made the professional astronomical community sit up and take notice of celestial objects other than planets and stars. Reigniting up the cause after Keeler's death, Heber Curtis generated even more momentum. The arsenal of data he gathered throughout the 1910s with the Crossley supported a very strong case that the spirals were no less than separate galaxies. Though it was all circumstantial evidence, Curtis's observations laid down a substantial foundation that made it far easier for Hubble to place the final capstone, his distance measurements to the closest spirals, that at last persuaded his fellow astronomers. Both Keeler and Curtis were vital pathfinders, carving out a route that led to Hubble's ultimate triumph.
In a similar fashion, Vesto Slipher spent many lonely hours at his Lowell Observatory telescope, year after year, building up the reservoir of galaxy velocities that Hubble then used to establish his historic link between a galaxy's redshift and its distance, a systematic pattern that served as powerful proof for the expanding universe predicted by Georges Lemaître. Yet Hubble remained remarkably silent about the meaning of what he and Humason had found. Neither in his personal conversations nor in his writings did Hubble discuss the implications of his finding on ideas concerning either the evolution of the universe from a primitive state or the necessity of a creation event. That would come from others. Hubble was not comfortable with imaginative speculation, beyond what his observations could plainly demonstrate. Hubble was always the skeptical scientist, forever the questioning lawyer.
Nevertheless this image of Hubble, someone aloof and hesitant to embrace a dynamic universe, slowly faded and was replaced by another portrait entirely. Over time, the story of the expanding universe's discovery evolved. Particularly after Hubble's death, more and more references were made to him as the sole discoverer of the universe's expansion. Poor Humason was shoved off to the shadowy sidelines of popular history, Slipher largely forgotten, and Lemaître's crucial theoretical interpretation diminished. Fine distinctions and the sharing of credit got lost. A rousing narrative is now usually drawn with Hubble as the main protagonist, even though in reality he was not the expanding universe's champion at all. But, as historians Kragh and Smith put it, “a growing community of American astronomers… by the 1960s were concentrating to an unprecedented degree on the study of galaxies [and] fashioned a hero, a founding father and a figure around whom they could drape a single version of the history of the discovery of the expanding universe.” The public seems to yearn for heroes, and thus Hubble—so handsome, so manly, so erudite—easily joined the scientific pantheon, along with Newton and his apple, Galileo and his telescope, Darwin and his finches.
It is the victorious leader who is now best remembered in the public's mind, not his accomplished predecessors or productive partner. Humason became Sancho Panza to Hubble's Don Quixote. Only this time, the twirling windmills are replaced with spiraling nebulae, and the celestial man of la Mancha ends up conquering them all with dazzling success.
Whatever Happened to…
In 1900
Charles Yerkes
moved to New York City, driven out of Chicago by anticorruption reformers. He went on to establish London's underground transit system. His fortune reduced, he died in 1905 at the age of sixty-eight, long estranged from his forty-seven-year-old wife, Mary Adelaide, who continued living in their Fifth Avenue mansion. Within a month, she married Wilson Mizner, a raconteur and scoundrel eighteen years younger, who was the basis for the character played by Clark Gable in the movie
San Francisco
. Mary divorced him a year and a half later.
To this day, the 40-inch telescope at the
Yerkes Observatory
, in southeast Wisconsin, maintains its status as the largest refractor in the world, although it is no longer used for professional research. Plans are under way to historically preserve the main building and convert it into a regional science center.
Percival Lowell
, long a bachelor, at last succumbed to marriage in 1908 at the age of fifty-three. He married Constance Savage Keith, nine years his junior and for many years a neighbor in Boston. At the end of a long honeymoon in Europe, he and his bride took a balloon ride, ascending a mile above London. There he photographed the paths of Hyde Park to see if its linear paths, substitutes for the Martian canals, could be detected from a high altitude. When Lowell died at Mars Hill in 1916 at the age of sixty-one, the observatory spent a decade fighting in court with his widow for control of his estate, the bulk of which he had intended to be used to carry on the observatory's work. Over that time, she squandered half of the $2.3 million. Constance reportedly lived in “opulent squalor” until her death in Massachusetts at the age of ninety in 1954. The following decade, Lowell's exotic imaginings were finally put to rest when a series of Mariner missions launched by the National Aeronautics and Space Administration in 1965 and 1969 showed Mars to be a completely barren world. When
Mariner 9
orbited the red planet in 1971, though, it photographed ancient riverbeds with tributaries and erosion patterns that appeared to have been carved by catastrophic flooding episodes. There were Martian channels after all, but these were forged by water flowing naturally in Mars's distant past rather than constructed by present-day aliens.
Whirlpool galaxy (M51) taken by the Hubble Space Telescope
(
NASA, ESA, S. Beckwith [STScI], and the Hubble Heritage
Team [STScI/AURA])
Besides his beloved Mars, Percival Lowell had another passion: searching for “Planet X” beyond Neptune. Analyzing discrepancies in the motions of Uranus and Neptune, he had come up with a predicted location for the missing planet, in the farthest realm of the comets some four billion miles from the Sun. The observatory's new director,
Vesto M. Slipher
, continued to administer the search. In 1930 a newly hired staff member, twenty-four-year-old Clyde Tombaugh, at last made the discovery. The new planet was named Pluto. The first two letters—
PL
—honored the man who initiated the planetary hunt. In 2006 Pluto, always considered an oddball because of its small size and eccentric orbit, was demoted to dwarf planet (a type of solar system body now called a plutoid), no longer one of the pantheon of classical planets.
Though detecting the swift speeds of the spiral nebulae was his most heralded accomplishment, Slipher made other notable discoveries during his long career. He played an important role in finding that interstellar space was not pristine but rather littered with faint wisps of gas and dust; connected certain features of auroras with solar activity; and accurately determined a number of planetary rotations. Slipher served as the Lowell Observatory's director for thirty-eight years. Esteemed by the townspeople, he prospered financially by shrewdly investing in ranch property, helping establish Flagstaff's community hotel, and running a retail furniture store at one point. His retirement in 1954 made the front page of the
Arizona Daily Sun
. He died in Flagstaff in 1969, three days before his ninety-fourth birthday.
After Lowell's death, the
Lowell Observatory
was often strapped for cash but survived, largely due to the astute administration (and added donations) of trustee Roger Lowell Putnam, Lowell's brother-in-law. Even then, the complex was surely headed for closure at the end of World War II, until the influx of federal funds into U.S. scientific research suddenly revived its resources. Today it continues its mission as a private, nonprofit education and research organization, carrying out studies on the solar system, comets, extrasolar planets, solar activity, and stars.
If
Heber Curtis
had stayed at the Lick Observatory, he might have had a chance of gathering the decisive proof that the spirals were island universes. But it's questionable that he would have extended his research to proving the cosmos was expanding. He was uncomfortable with Einstein's theory and participated in solar-eclipse tests hoping to prove general relativity wrong. In the 1930s he told Harlow Shapley that he wasn't keen on where the research on spiral nebulae was going: “I have so little confidence in the theories of Lemaître, Eddington,
et al.
in this field that I shall follow the safe if not sane course of just sitting tight.” After spending ten years as director of the Allegheny Observatory, Curtis came full circle and finished up his career in the 1930s at the University of Michigan, where he had begun his undergraduate studies in the classics. He had hopes for erecting a big reflector for Michigan's use but the Depression intervened, dashing his plans. Curtis died in 1942. He always considered his work on the nebulae as his greatest contribution to astronomy.
The
Lick Observatory
continues to be owned and operated by the University of California. More than twenty families currently reside on the mountain, with the town maintaining its own police department and post office. While the Crossley reflector remains in operation for professional research, the Lick 36-inch refractor is primarily a popular attraction, used at scheduled times for public viewing. Since the 1920s, the observatory grounds have expanded to include nine research-grade telescopes, the largest being the 3-meter (120-inch) Shane Reflector.
George Ellery Hale
died at the age of sixty-nine in 1938, a decade after he launched an endeavor to erect a 200-inch telescope atop California's Palomar Mountain, near San Diego. The telescope was at last dedicated in 1948. To venerate Hale's brilliant leadership in the telescope's design and construction and his achievements as the Mount Wilson Observatory director from 1904 to 1923, the 200-inch was named the Hale Telescope. One wonders what Hale's reaction might have been to this honor if he had lived to see the telescope in operation. “The truth is,” he once noted, “… that I have been enjoying from boyhood the things I liked most to do, and why should one be praised for simply having a good time?” Six decades later, the Hale Telescope remains one of the larger optical telescopes in the world and continues to make major contributions to astronomical research.
Telescope designer
George Willis Ritchey
, who had supervised the optical work on the 100-inch Hooker Telescope, continued to bad-mouth the venture after Hale ordered its flawed disk polished and mounted. Once Hale nixed Ritchey's grandiose idea to replace the defective glass with a radically new type of mirror, the optician spread the word that the giant scope would fail. In an act of insubordination, Ritchey directly contacted Hooker, Hale's benefactor, to convince the businessman to take his side. Ritchey's gossip and unauthorized dealings—acts of disloyalty to Hale—ultimately led to his dismissal from Mount Wilson in 1919 at the age of fifty-four. Ritchey never got to use the Hooker telescope for his own astronomical investigations. He moved to his ranch east of Pasadena, growing lemons, oranges, and avocados and dreaming of designing ever-bigger telescopes, with mirrors up to 320 inches in width. In the 1920s he worked in France in an attempt to construct a telescope that would surpass the Hooker in size, until the French project was called off. In the early 1930s he had to settle for designing and constructing a 40-inch reflector for the U.S. Naval Observatory, then upgrading its equipment in Washington. He died in 1945, two months shy of eighty-one. He would never learn that his highly controversial design for the Naval Observatory scope, worked out earlier in collaboration with the French astronomer Henri Chrétien, would later be used in many giant telescopes built in the latter half of the twentieth century, including the Hubble Space Telescope.
Edwin Hubble's
later work never quite equaled the amazing discoveries he made in the 1920s and early 1930s. His most productive days were behind him. His scientific life, in a way, came to a standstill as he awaited construction of a bigger telescope to advance his cosmic searches. During World War II, he was stationed at the U.S. Army's Ballistics Research Laboratory at Aberdeen, Maryland. There he applied his student training in orbital mechanics to calculating artillery-shell trajectories. Over the years, his noted arrogance tempered a bit. Astronomer George Abell, who briefly worked for Hubble while a graduate student in the early 1950s, remembered him as a “very gracious, kindly person, a real gentleman… He always seemed to have time to talk to students and night assistants… He may have mellowed in his old age.” Hubble lived long enough to see the opening of the next great telescope after the 100-inch—the 200-inch telescope on Palomar Mountain. He was the first scheduled observer on the giant instrument in 1949 and got started by photographing the variable nebula NGC 2261, his good luck charm. The many snubs toward his colleagues over the years, though, ultimately kept him from his more cherished goal: becoming director of the newly combined Mount Wilson and Palomar observatories. Ira Bowen was appointed instead, a decision that simply stunned Hubble, who was certain the post was his for the taking. During the following summer, on a fishing trip near Grand Junction, Colorado, Hubble experienced a major heart attack and was hospitalized.
On September 28, 1953, the Hubbles were returning to their San Marino home by car, with Grace driving. Hubble was in the midst of preparations for going to Palomar for four nights of observing. When Grace was about to make a turn into their driveway, though, she noticed Edwin breathing shallowly. “Don't stop,” he said. “Drive on in.” By the time she parked in their front courtyard, he had died of a cerebral thrombosis. He was sixty-three. Grace lived for another twenty-seven years, vigilantly editing her husband's legacy.
Milton Humason
, who had barely finished the eighth grade before dropping out of school to work at Mount Wilson, received an honorary doctorate from Sweden's Lund University in 1950 for his historic contributions to the discovery of the expanding universe, becoming that rare individual who went from elementary school directly to a PhD. By the end of his career, Humason had taken the spectra of more than six hundred galaxies. At his retirement, his son offered to buy him a small telescope to continue viewing the sky. “My God, Bill,” he replied, “I've looked in an eyepiece all my life, I don't want to look in any more eyepieces.” He went salmon fishing instead.
The Carnegie Institution of Washington continues to own and operate the
Mount Wilson Observatory
, although now in partnership with the Mount Wilson Institute, a nonprofit corporation established in 1985. The 100-inch Hooker Telescope was temporarily shut down in 1986 as a cost-cutting measure but brought back into operation in 1992. With the use of advanced technology instruments to analyze the light gathered by its mirror, the Hooker continues to carry out valuable research, such as searching for extrasolar planets and monitoring sunspot cycles on other stars.
The years that
Harlow Shapley
spent at Mount Wilson, proving our true place within the Milky Way, turned out to be the “high noon of his scientific life.” After World War II, he sharply curtailed his astronomical research efforts and devoted more of his time to national and international affairs. An unabashed liberal, he played a leading role in the formation of UNESCO, the United Nations Educational, Scientific and Cultural Organization. His activities on behalf of world peace and his continuing contacts with Russian scientists brought him under investigation in 1946 by the infamous House Committee on Un-American Activities. Senator Joseph McCarthy later accused him—wrongly—of being a Communist. After Shapley retired as director in 1952, the Harvard Observatory continued to be his academic home for yet another twenty years, until his death in 1972 at the age of eighty-six. He was buried in Sharon, New Hampshire, where he had lived for many years after his retirement. His grave is marked by a solid granite rock upon which is inscribed, “And We by His Triumph Are Lifted Level with the Skies,” a quotation from the ancient Roman philosopher Lucretius.
