The 4-Percent Universe

by Richard Panek

  Sitting in the Black Hole Café, Schmidt took a sip of wine, pronounced it palatable, and said that he had to disagree with Rocky. "There is no reality," he said to Wetterich. "There are only predictions."

  Wetterich said he had to agree with Rocky. To make his point, he picked up a water glass. "If I drop it," he said, "it will fall to the table."

  Schmidt shook his head. Yes, he conceded, every glass throughout history, when released, has fallen. "But once it might not," he said. "You can only predict that it will—to a high degree of confidence," he added.

  "I believe it will," Wetterich said.

  Schmidt shrugged. "I hope it won't."

  The meaning of reality might seem a subject best left to philosophers, but, like philosophy itself, it had always been the domain of physicists, too. The ancients thought they couldn't capture "reality," so they settled for saving the appearances. Once Galileo had provided empirical evidence that Copernicus's Sun-centered system was correct, and once Newton had codified the math, scientists came to understand that equations on paper could do more than approximate reality: If you could find it in the heavens, you could capture it on paper—the point Kolb was trying to make. Then Einstein came along and reversed that process. If you could write it on paper, you could find it in the heavens.* If your equations told you that time passed differently for two observers moving in relation to each other, or that gravity bent light, then that was what nature did. You would, Einstein acknowledged, have to test those predictions: "Experience remains, of course, the sole criterion of the physical utility of a mathematical construction"—the point Schmidt was making to Wetterich. If you found an exception in nature, then you either adjusted or abandoned the theory. But Einstein, speaking from his own experience, then proceeded to argue the point that Wetterich was making to Schmidt: "I hold it that pure thought can grasp reality, as the ancients dreamed."

  Schmidt and Wetterich weren't going to settle the debate. It was ancient; it was eternal. For Schmidt, though, it was also personal. In 1998, he'd let go of a glass and it went up.

  However transcendent the discovery, the human repurcussions sometimes weighed heavily on Schmidt. This was one of those times. That spring, just prior to the McMaster and Perimeter meetings, Schmidt had heard from the Peter and Patricia Gruber Foundation—a philanthropy made possible by a Wall Street fortune—that he and Saul were the recipients of that year's Gruber Prize in Cosmology, worth $500,000. They were in excellent company. Jim Peebles and Allan Sandage had shared the first cosmology prize, in 2000; other recipients had included Vera Rubin in 2002, and Alan Guth and Andrei Linde in 2004. The apportionment of credit for the 2007 prize was understandable. According to the unwritten rules of science, Brian Schmidt was the big gun on the High-z team. But the team had deliberately tried to rewrite those unwritten rules, and Schmidt was still trying: All week he had been negotiating with the foundation, requesting that Adam Riess be added to the list of recipients because he had been the author of the "discovery of acceleration" paper for the High-z team.

  The nuances were more than academic. Once while Perlmutter was making a presentation at a conference, Nick Suntzeff turned to Bob Kirshner and whispered, "Saul thinks there's a Nobel Prize in this."

  Kirshner gave Suntzeff a look. "There is!"*

  The Grubers were, in a way, the Golden Globes to the Nobel's Academy Awards. The preceding year, 2006, the Gruber Prize in Cosmology had gone to John Mather and the COBE team. Then a few months later the Nobel Prize in Physics went to Mather and his COBE collaborator George Smoot. That the discovery of acceleration was worthy of a Nobel Prize wasn't subject to much debate. What was debated was who made the discovery. "Saul is going to win a Nobel Prize," Alex Filippenko would say, with a shrug. "My only hope is that the Nobel committee will do the right thing and give it to Brian and Adam as well. That would be the fair thing. All right?"—this last said as if there were someone challenging him, which in a sense there was.

  The two teams had long before informally agreed that the discovery was, as Riess would say, "big enough and cool enough to share." The standard construction was that in early 1998 two teams had independently reached the same surprising conclusion—that the expansion of the universe appeared to be accelerating. In June 2006, Perlmutter, Riess, and Schmidt learned that they had won the Shaw Prize in Astronomy, a $1 million award endowed by the Hong Kong media magnate Sir Run Run Shaw in 2002. (Jim Peebles had gotten here first, too, in 2004.) So far, so good. But the following month, July 2006, came the announcement that the Antonio Feltrinelli International Prize in Physical and Mathematical Sciences—awarded once every five years by Italy's Accademia Nazionale dei Lince, or Academy of Lynxes, dating back (albeit with a centuries-long interruption) to Galileo's day, and carrying an award of about $315,000—was going to Perlmutter ... and only Perlmutter.

  Members of the High-z team interpreted this news as evidence that the Berkeley Lab "publicity machine" had done its job. They still recalled how George Smoot in 1992 had broken the agreement not to publicize the COBE results before the public announcement; to make matters worse, as Mather wrote in a book about the project, the LBL press release "mentioned NASA only in passing and did not cite a single member of the COBE science working group other than George." Now, members of the High-z team feared, the LBL press office was performing the same beyond-the-call-of-duty (and possibly of ethics) service for Saul, making him "appear to be God and the greatest thing since sliced bread," in the words of Filippenko. It had persuaded someone, somewhere, in a position of influence that in the January 1, 1998, Nature paper, or maybe at the January 8, 1998, AAS press conference, or maybe among the January 9, 1998, AAS posters, the Supernova Cosmology Project had announced the discovery of cosmic acceleration.

  Members of the SCP, however, had long thought that the High-z team was trying to discredit them. In 2001 Filippenko's personal account of his experience as the only astronomer who was a member of both teams appeared as an article in Publications of the Astronomical Society of the Pacific; the following year Bob Kirshner published his own personal account as a book, The Extravagant Universe. After Mike Turner reviewed Kirshner's book for Science, LBL's Robert Cahn—still seething from his own experience having to defend the SCP from Kirshner's recommendation to shut it down, followed by Kirshner's appropriation of Perlmutter's Hubble Space Telescope plans—said to Turner, "Well, it tells me something that after their results, Saul set out to design an experiment in space to really understand this, and Kirshner decided to write his memoirs." Or as one member of the SCP collaboration remarked, pretty much summarizing the response of the whole team, "The High-z accounts don't recognize the other side of the Mississippi." For his part Perlmutter asked the LBL publicity department to compile a preemptive history of the discovery, then file it away for the day it might be most useful.

  As the tenth anniversary of the discovery grew closer, tensions grew stronger. At one cosmology conference "celebration" of the anniversary, Gerson Goldhaber reviewed the history of the discovery, concentrating on his histogram from the fall of 1997. "I'm mentioning the dates," he said, "because the date of discovery is of some importance." He also talked about the colloquia that Perlmutter had given late that year. "Now, the question is, who remembers all that?" he said. "Well, Saul's talk was videotaped, and I have the videotape."

  Riess followed him. He opened his talk by wishing Goldhaber a happy birthday. Goldhaber nodded and accepted the applause of the audience. Then Riess showed some of his team's e-mails from January 1998. And then he showed a clip from his appearance on the McNeil-Lehrer NewsHour on the day that Science published an article on Filippenko's talk at the UCLA meeting.

  The following morning it was Perlmutter's turn. He opened by saying he hadn't planned to focus on the past, but he did want to show that on January 9, 1998, his team had their "equivalent of the McNeil-Lehrer" moment with the publication of the front-page article in the San Francisco Chronicle covering his participation in the AAS press conferen
ce, and although he didn't have e-mails from that period, he did have their "equivalent"—the minutes of the team's meetings from the fall of 1997, which he also displayed.

  "Dear Saul," Bob Kirshner began a letter dated January 12, 2007:

  I was dreamily thinking about 2006, as people often do on the final day of the year.

  As part of this idle foolishness, I took a look at the Shaw Prize site. I want to say again that I think this award is a great thing and I am very glad the cosmic acceleration is being recognized. You have a lot to be proud of, and I feel the same way about the work that Adam and Brian and the rest of us have done.

  But there was one point that jumped out at me and I can't get it out of my mind. That is why I am writing to you.

  Over the years Brian Schmidt had come to recognize that Kirshner's promotion of Schmidt's thesis work at conferences in the early 1990s—however much the two of them might have disagreed about the apportionment of credit—was part of what a big gun did: get the word out to the community about an acolyte's accomplishments. Now Kirshner had taken on similar duties regarding the High-z team's accomplishments, peppering magazines and newspapers with letters and e-mails objecting to coverage that, in his opinion, favored the SCP.

  In this case, he was objecting to the mini-autobiography that Perlmutter had written for the Shaw Prize website, in particular this passage: "We announced these results at the American Astronomical Society January 1998 meeting. Because both our team and Brian's team—including Shaw co-winner Adam Riess—independently announced matching results at conferences in the beginning of the year, by the end of the year most of the scientific community had accepted the startling findings." Over seven single-spaced pages, Kirshner proceeded to quote from (and link to) the LBL's January 8, 1998, press release, contemporaneous press accounts, and books to support his conclusion that Perlmutter "did not announce," "did not announce," " did not announce," and, for good measure, "did not make an announcement" (boldface his) of acceleration in January 1998.

  When Kirshner didn't hear back from Perlmutter, he revised the letter, removing the salutation and the references to "you," among other modifications, and on February 27, 2007, he posted it on his Harvard website under the link "Thoughts on the discovery of dark energy."

  "Dear Bob," Perlmutter finally replied, in a letter dated June 12, 2007:

  Now that the teaching semester is over let me address the 9-page letter that you sent concerning our January 1998 AAS scientific presentation and press conference. As I mentioned in my earlier email I was greatly surprised by your letter, and in fact had previously been thinking I should email a request to a few members of the original High-Z team that they stop referring to our January announcement as "weaker" or "more tentative" than the High-Z team Marina Del Rey announcement, since I think this is incorrect. However, before your email I had never heard the suggestion made that we had not presented *any* substantive results at the January meeting. (Obviously, there is no question about which group's paper got out first, but you are clearly making a broader claim here that I believe misrepresents the history.)

  The controversy was coming down to the meaning of the word "announce." A month later, responding to Perlmutter's letter, Kirshner addressed the issue directly: "Did you or did you not 'announce' the accelerating universe at the AAS meeting in January 1998? 'Announcing' is what you claim to have done in your Shaw autobiography. Twice. That's what your letter aims to show. After reading your letter, I am even more convinced that this is not correct." And he went on, for yet another seven single-spaced pages, to cite some of the same press accounts as before, as well as to rebut the references that Perlmutter had included in his June letter, including the front-page article by Charles Petit in the San Francisco Chronicle that ran under the sub-headline "Universe getting bigger and bigger, faster and faster—forever," and reported that the SCP study "seems to indicate" that the "expansion is starting to speed up."*

  This time Perlmutter didn't bother to respond.

  During the pre-anniversary period, tensions grew stronger within the teams as well. In 2007, even while he was exchanging gritted-teeth pleasantries with Perlmutter, Kirshner managed to alienate some of his collaborators. For a talk entitled "Supernovae and the Accelerating Universe" at the Aspen Center for Physics, Kirshner presented "A Timeline of Important Developments" that, among multiple references to the High-z group, included exactly one mention of Brian Schmidt—a (near) omission that only reinforced the feeling among some team members that Kirshner took "too much credit for himself." Nor was the SCP team immune from this self-cannibalization. Gerson Goldhaber began circulating his own history of the discovery, which underwent several revisions to accommodate the complaints of some SCP collaborators who felt he was claiming the discovery for himself. Privately, though, Goldhaber stuck to his story: "My team found it first, and I found it for my team."

  As part of the preparation for the tenth anniversary, STScI—Riess's home turf—sponsored a media day; Perlmutter flew in from the West Coast for the occasion. A week later, Newsweek ran an article on dark energy that led with a re-creation of Riess's 1997 calculation of a universe with negative mass, and went on to quote Kirshner on the cosmological constant. Not only did Perlmutter and the SCP receive no mention, neither did the existence of any discoverer other than Riess (aside from a reference to "and his colleagues").

  That did it. Perlmutter contacted the LBL press office: The time had come to release the SCP version of the history of the discovery of dark energy. Shortly thereafter it appeared on the Berkeley Lab website as a three-part series. Part One began: "Saul Perlmutter, leader of the international Supernova Cosmology Project (SCP) based at Berkeley Lab, made the first public announcement of evidence for the accelerating expansion of the universe on January 8, 1998...."

  In Cambridge, in an office half a mile up Garden Street from Harvard Square, a quivering hand reached for a keyboard.

  This wasn't the legacy Schmidt or any of the other members of the two teams wanted for themselves: bickering eggheads. And now they couldn't even guarantee that they had done their discipline proud.

  "Fundamentalist Physics: Why Dark Energy Is Bad for Astronomy." The title alone would have guaranteed that the paper would get attention. That its author was Simon White, one of the directors at the Max Planck Institute for Astrophysics, Germany, guaranteed that it would get serious consideration. That it presented arguments the community had begun finding unavoidable made it a sensation.

  The paper appeared online in April 2007, in advance of publication in the journal Reports on Progress in Physics and just prior to the McMaster conference and Perimeter workshop. Like the contentiousness over the Gruber Prize, the paper preoccupied Schmidt that week, not only because everybody else was talking about it, but because he was sympathetic to a lot of what White had to say. The core of White's argument was that astronomy and particle physics constituted two different cultures. Astronomers, White said, were "generalists," exploring the complexities of the universe on a case-by-case basis. Particle physicists were "fundamentalists," wringing the complexities of the universe in the hope of squeezing out an "ultimate foundation"—a "Truth." "Dark Energy," he wrote, "is a unique link between them, reflecting deep aspects of the Fundamental Theory, yet apparently accessible only through astronomical observation."

  In the theory-and-observation, call-and-response system of investigating nature that scientists had refined over the previous four hundred years, the dark side of the universe represented an irruption. Copernicus's heliocentric theory anticipated Galileo's observations of Jupiter and Venus, which inspired Newton's theory of universal gravitation, which anticipated more than two centuries' worth of moons, planets, and stars, which inspired Einstein's theory of general relativity, which anticipated the observations of the expanding universe, which inspired the Big Bang theory, which anticipated the observations of the cosmic microwave background, which inspired the revival of Einstein's theoretical cosmological constant, which
anticipated the observations of Type Ia supernovae, which inspired ... what? Not a theory, exactly. Just a name for a theory—and not even a theory. A theory-to-be: dark energy.

  "We're desperate for your help," Schmidt had called to the theorists in the audience at another cosmology meeting a couple of years earlier. "You tell us what you need, we'll go out and get it for you."

  To which the most succinct response was one his old officemate theorist Sean Carroll offered at yet another cosmology meeting: "We have not a clue."

  Not a clue, yet no end of ideas. Every day Adam Riess checked an Internet site where scientists posted papers; he was hoping for the paper that would finally present a "deep theory," but he found most of them "pretty kooky." Saul Perlmutter liked to begin public talks with a PowerPoint illustration: papers on dark energy piling up, one on top of the next, until the on-screen stack ascended into the dozens. Schmidt had looked online at how many papers cited the original dark-energy papers and found three thousand—of which twenty-five hundred were theories. In his talk at McMaster, he had included a list of prospective candidates for dark energy that a friend had culled from the recent literature:

  Tracker Quintessence, single exp Quintessence, double exp Quintessence, Pseudo-Nambo-Goldstone Boson Quintessence, Holographic dark energy, cosmic strings, cosmic domain walls, axion-photon coupling, phantom dark energy, Cardassian model, brane cosmology (extra-dimension), Van Der Waals Quintessence, Dilaton, Generalized Chaplygin gas, Quintessential inflation, Unified Dark matter and Dark energy, superhorizon perturbations, Undulant Univese, various numerology, Quiessence, general oscillatory models, Milne-Born-Infeld model, k-essence, chameleon, k-chameleon, f(R) gravity, perfect fluid dark energy, adiabatic matter creation, varying G etc, scalar-tensor gravity, double scalar field, scalar+spinor, Quintom model, SO(1,1) scalar field, five-dimensional Ricci flat Bouncing cosmology, scaling dark energy, radion, DGP gravity, Gauss-Bonnet gravity, tachyons, power-law expansion, Phantom k-essence, vector dark energy, Dilatonic ghost condensate dark energy, Quintessential Maldacena-Maoz dark energy, superquintessence, vacuum-driven metamorphosis