The Day We Found the Universe

by Marcia Bartusiak

  There was much to argue about. Those still skeptical of general relativity were offering other explanations for the outward march of the galaxies. British cosmologist E. Arthur Milne, for example, posited that the expansion of space-time was merely an illusion. Space was steady as a rock, but the spiral nebulae upon forming started moving in random directions and with different velocities. Over the eons, the nebulae with the fastest speeds naturally moved farther out, setting up the appearance of a cosmic expansion. It was a model that philosophically pleased Milne, who didn't believe space could possibly curve, bend, or move.

  Caltech astronomer Fritz Zwicky proposed that light waves, as they traveled through space, could be interacting with matter, setting up a sort of gravitational drag. The more a light wave traveled, the more it lost energy, shifting its wavelength toward the red end of the spectrum. It resembled the de Sitter effect, only this time matter was doing the work. This could explain why the nebulae farthest out displayed the largest redshifts. Space wasn't expanding at all; the photons of light were simply getting weaker and weaker in their journey through a matter-filled cosmos. Hence, this model came to be known as the “tired photon” theory. There was no natural way to explain how this would happen; it required a new law of physics, but that didn't deter Zwicky at all. He was a legend among astronomers for his chutzpah. He felt his explanation might be pointing to a new physical phenomenon.

  Hubble worked for a number of years with Caltech theorist Richard Tolman on how to test these competing models of the universe. They wanted to see which one was most compatible with the data arriving at the telescope. Their effort eventually came to naught. Given the state of astronomy at the time and the instruments available, there were simply too many uncertainties—too much guesswork—to reliably choose one cosmological model over another. Their initial data, though, seemed to better support some alternative theories, like Zwicky's “tired photon” scheme. But Hubble made the call that his data were too uncertain, which kept the expanding universe in play. “We cannot assume that our knowledge of physical principles is yet complete,” he wrote, “nevertheless, we should not replace a known, familiar principle, by an ad hoc explanation unless we are forced to that step by actual observations.” To back away from Einstein, the proof for Hubble had to be overwhelming. On the other hand, the uncertainty of it all likely reinforced his qualms at advocating any particular interpretation.

  Lick astronomer C. Donald Shane, in talks with Hubble in the 1930s, actually got the impression that Hubble had “a desire to show that the red shift was not an expansion…because he seemed always to be seeking some other explanation for it.” Perusing Hubble's writings on the idea of an expanding universe, you immediately detect that he was uncomfortable with it. He acceded that theorists were “fully justified” in interpreting the galaxy redshifts as a movement outward; it was the most reasonable explanation that required no new laws of physics. But then he would invariably sneak an “on the other hand” into his script. He deemed a static and infinite universe more “plausible” and “familiar,” like a pair of old shoes he found difficult to throw out. In his Rhodes Memorial Lectures, delivered at Oxford in the autumn of 1936, Hubble reaffirmed his vacillation over the interpretation of the redshifts. Their “significance is still uncertain,” he stated. With the recent introduction of both quantum mechanics and relativity, which demonstrated quite explicitly that scientists' understanding of nature can change abruptly and in surprising ways, perhaps Hubble's caution was understandable. In his lecture Hubble went on to describe the expanding universe as a “dubious world,” though still conceding it was the more likely interpretation of the redshifts. But with alternate explanations still in play, he concluded that astronomers were in “a dilemma [whose] resolution must await improved observations or improved theory or both.”

  What seemed to disturb Hubble most were the enormous velocities. The farther he and Humason extended their searches into space, the faster and faster the galaxies were retreating. Near the absolute limit of Humason's spectrograph, he recorded velocities of about 25,000 miles per second, “around the earth in a second, out to the moon in 10 seconds, out to the sun in just over an hour…the notion is rather startling,” noted Hubble.

  As late as 1950, responding to a Kansas professor's written inquiry about redshifts, Hubble asserted that they “represent either actual recession (expanding universe) or some hitherto unknown principle of nature. I believe that the choice of these alternatives will be determined with the 200-inch [telescope on California's Palomar Mountain] within a few years.” Maintaining his lawyerly ways, Hubble covered all the bases when making a public statement.

  Others, such as Eddington, were confounded by such equivocation. “I just don't understand this eagerness to find some other theory than the expanding universe,” he wrote in a letter to a colleague. “It arose out of difficulties … in Einstein's theory. If you do away with it, you throw back relativity theory into the infantile diseases of 25 years ago. And why the fact that the solution then found has received remarkable confirmation by observation should lead people to seek desperately for ways to avoid it, I cannot imagine.”

  While Hubble remained overly cautious, Shapley came to embrace the idea of an expansion lock, stock, and cosmic barrel. It's as if the two astronomers were magnets with the same polarity, always repulsing each other to opposite sides of a question. The ultimate imprimatur, though, was provided when Einstein arrived in Pasadena in 1931 in order to consult with the high priests of cosmology at both Caltech and Mount Wilson.

  Started Off with a Bang

  On November 30, 1930, Einstein, his wife, Elsa, his secretary, and a scientific assistant left Berlin for Antwerp, where they embarked on the steamer Belgenland. It was Einstein's second visit to the United States but his first journey to America's West Coast. Before leaving, Frau Einstein made a last-minute shopping trip to purchase a raincoat for the father of relativity. “Would it not be more practical to have the herr professor come here so we can give him an exact fit?” said the clothing store salesman. “If you knew how hard it was even to persuade my husband he needed a new coat, you wouldn't expect me to fetch him here. I wish you had my worries,” she replied. It was teasingly said that Einstein was going to Pasadena to hunt for the sole twelve men in the world who could understand him.

  The revered physicist arrived in New York on December 11, where he and Elsa were greeted by a barrage of journalists, photographers, and newsreel men, a chaotic scene that greatly discomfited Einstein. “This reminds me of a Punch and Judy show, all of you standing there watching us so intently,” he remarked in German. The press described him that day as small, bright-eyed, his almost white hair trained back in a bushy pompadour, and “his face … as smooth as a girl's except for the tiny wrinkles about his eyes.” Out on the deck, a cold damp wind soon blew through his locks, swiftly turning the carefully groomed pompadour into his well-known disheveled hairstyle. After a four-day stay in New York, he and his party continued their voyage on the Belgenland for California, by way of the Panama Canal.

  Arthur Fleming, a member of the California Institute of Technology's executive council, first extended the invitation to visit, extolling his town's summery climate and rich scientific atmosphere. Einstein, then looking for a good rest among men who spoke the language of mathematics, eagerly accepted. For one, it was an opportunity for him to meet Albert A. Michelson, the physicist whose inexplicable failure to measure a predicted change in the speed of light due to Earth's motion through an “ether” permeating space was at last explained by Einstein's special theory of relativity, which did away with the ether altogether.

  Aware of Einstein's dislike for publicity, his California hosts tried to dispense with an official welcome, as in New York, but to no avail. Upon docking in San Diego on New Year's Eve, the German visitors had to endure four hours of speeches, presentations, tours, and a radio talk. Only after all the hoopla had ceased were Einstein and Elsa finally taken northward by ca
r, eventually settling into a small Pasadena bungalow specially renovated and furnished for their stay. While shunning many public events over their two-month visit, the Einsteins enjoyed a steady round of private engagements. Over the ensuing weeks, they hosted a dinner for the director of the Los Angeles Philharmonic (with Einstein briefly playing the violin for his guest), visited a Hollywood studio, had dinner at the home of film comedian Charlie Chaplin, and motored out to Palm Springs for a four-day holiday. They did put up with the glare of the celebrity spotlight on one special occasion. The couple, he decked out in tuxedo and she in full-length evening gown, attended the premiere of Chaplin's latest movie, City Lights, where Einstein laughed like a little boy. There was a simple reason for this exceptional night on the town: Chaplin, instantly recognizable throughout the world, was Elsa's matinee idol. “They cheer me because they all understand me, and they cheer you because no one understands you,” Chaplin told Einstein as they walked into the theater to shouts and clapping that night.

  Einstein's days, though, were solely devoted to research, with visits to either Caltech or Mount Wilson's Pasadena headquarters for talks and consultations with fellow scientists. For his convenience, he had a small army of chauffeurs at his beck and call, including Grace Hubble. When driving Einstein to an engagement one day, he turned to her and said, “Your husband's work is beautiful—and he has a beautiful spirit.” Einstein had been given a room at Mount Wilson's main offices right across from Hubble's. The observatory made every attempt to shelter him from the press and allow him maximum time to interact with his colleagues, even keeping the doors locked at the headquarters and issuing keys. Hale, though, stayed away from all the partying. “I have kept completely out of the Einstein excitement,” he told a friend, “and have not seen him at all until he dropped into my lab the other day, fortunately with no reporter. He is very simple and agreeable and greatly dislikes all the newspaper notoriety. But as the town is swarming with reporters, several of them sent out here for the occasion by eastern papers, he cannot escape entirely.”

  Einstein and his wife, Elsa, with Charlie Chaplin at the premiere

  of Chaplin's film City Lights, January 1931 (Copyright Jewish

  Chronicle Ltd/HIP/The Image Works)

  That was certainly the case on January 29, 1931, when a carefully orchestrated expedition was arranged for Einstein. That morning the world's premier physicist and Hubble, its foremost astronomer, settled into the plush leather seats of a sleek Pierce-Arrow touring car and traveled, along with a number of other observatory staffers, up to the site of Hubble's astronomical triumphs—the sprawling telescope complex atop Mount Wilson. Despite warnings from his doctor to avoid high elevations, Einstein was eager to make the trek, so he could view up close the machinery that had had such a direct bearing on his theoretical investigations.

  This event was considered so noteworthy that a young filmmaker named Frank Capra, still three years away from his first Academy Award for the screwball comedy It Happened One Night, came along to document Einstein's every move on the mountain that day. Clambering with a few others into an open steel box, operated by cables, Einstein was first carried to the top of the 150-foot-high tower telescope, used exclusively for the study of the Sun. After admiring the view of southern California and duly photographed in the cold, stiff breeze, he again went aboard the miniature elevator back to the ground. “And here he comes,” said the announcer in the newsreel's opening, “down from the sun tower, after a hard morning, looking a few million miles into his favorite space.”

  After lunch came the opportunity to visit the 100-inch telescope, where Einstein again dutifully posed for Capra, peering through the eyepiece while Walter Adams stiffly spoke, directly to the camera. “This hundred-inch reflector was completed about thirteen years ago and has contributed in three or four notable ways to progress in astronomy,” he droned. All the while Hubble was also in the frame, wearing his sporting plus-fours (golf trousers cut four inches below the knee) and silently puffing away on his ever-present pipe. Away from the camera, Einstein delighted in the telescope's instruments. This was his first view of a large reflecting telescope, and he was quick to grasp the intricacies in its construction and operation. Like a child at play, the fifty-one-year-old physicist scrambled about the framework, to the consternation of his hosts. Nearby was Einstein's wife. Told that the giant reflector was used to determine the universe's shape, Elsa reportedly replied with wifely pride, “Well, my husband does that on the back of an old envelope.”

  For the cameras Einstein pretends to peer through the 100-inch

  telescope during his visit to Mount Wilson. Edwin Hubble (center)

  smokes his pipe and observatory director Walter Adams (right) looks on.

  (Courtesy of the Archives, California Institute of Technology)

  After an early dinner the party returned to the 100-inch telescope, when Einstein was at last able to do some real observing, peering at Jupiter, Mars, the asteroid Eros, several spiral nebulae, and the faint companion of the star Sirius. He remained in the dome until after one o'clock, finally retiring under protest and with the stipulation that he be called in time to see the sunrise. Everyone returned to Pasadena at about ten o'clock that same morning.

  Five days later, astronomers and theorists gathered in the spacious library of the observatory's Pasadena offices, books lining the walls from floor to ceiling, to hear Einstein's assessment of what he had learned and absorbed from his visit to the mountain. Up to this point, he had been very wary of considering a universe in restless motion, curtly dismissing the models fashioned by both Friedmann and Lemaître. Einstein, by far, preferred a universe that stayed put. But on that day he at last conceded that the secret of the cosmos had undoubtedly been revealed by Hubble's observations. Einstein at last let go of his spherical universe. “A gasp of astonishment swept through the library,” according to an Associated Press reporter in attendance. At a follow-up session a week later, Einstein went further and announced that “the red shift of distant nebulae has smashed my old construction like a hammer blow,” swiftly swinging down his hand to illustrate the point to his audience. Einstein at this stage recognized that he no longer needed his cosmological constant to describe this dynamic universe. His original equations could handle the cosmic expansion just fine, which pleased him immensely. From the start, he had had qualms about the ad hoc addition, believing the constant tarnished the formal beauty of his theory. Tacking on the extra term, he reportedly said, was the “biggest blunder” he ever made in his life. The cocky kid was getting older. If he had trusted his equations from the start, he could have predicted that space-time was in motion years before Hubble and Humason confirmed it, which would have rocketed Einstein's reputation, towering as it was, into the stratosphere.

  Einstein with Hubble (second from the left) and others from Caltech

  and the observatory outside the dome of the 100-inch telescope during

  his visit to Mount Wilson on January 29, 1931 (Courtesy of the

  Archives, California Institute of Technology)

  Given his role in this turnabout, Hubble was soon revered as the man who “made Einstein change his mind.” Aside from perhaps receiving a Nobel Prize, there was no higher accolade in science at the time.

  A few weeks before Einstein roamed over the summit of Mount Wilson, Eddington delivered an address to the British Mathematical Association, where he called attention to the notorious elephant in the room, present ever since Lemaître first introduced the concept of an expanding universe. In his masterly 1927 journal article, Lemaître had coyly asked the question that likely arose in the mind of anyone reading the paper: How did this expansion get started? “It remains to find the cause,” he answered at the time.

  Eddington in his January 5 talk to the British mathematicians faced this conundrum head-on. In his mind's eye, he mentally put the expansion of space-time into reverse and pondered the condition of the universe at earlier and earlier epochs, back to the
very launch of space, time, and all of creation. Could you reach a “beginning of time,” he asked, when all matter and energy had the highest degree of organization possible? Eddington was horrified by this thought. The Cambridge theorist concluded that “philosophically, the notion of a beginning of the present order of Nature is repugnant to me…. By sweeping it far enough away from the sphere of our current physical problems, we fancy we have got rid of it. It is only when some of us are so misguided as to try to get back billions of years into the past that we find the sweepings all piled up like a high wall and forming a boundary—a beginning of time—which we cannot climb over.” A few years earlier, before the reason for the retreating galaxies was even known and he was simply contemplating an early universe with more energy and order, Eddington had already declared that he did “not believe that the present order of things started off with a bang” (a precursor to British astronomer Fred Hoyle using a similar description on a 1949 BBC radio program, this time with an added adjective, which secured the scientific name—Big Bang—for the moment of creation). Eddington, though, preferred a commencement less abrupt and more restrained. “I picture…an even distribution of protons and electrons, extremely diffuse and filling all (spherical) space, remaining nearly balanced for an exceedingly long time until its inherent instability prevails… There is no hurry for anything to begin to happen. But at last small irregular tendencies accumulate, and evolution gets under way…. As the matter drew closer together in the condensations, the various evolutionary processes followed—evolution of stars, evolution of the more complex elements, evolution of planets and life.” The universe, in effect, eased into its expansion, like a massive train starting up slowly and then gaining speed.