Where they crossed, X marks the spot, and that's where the treasure was buried. and £2A. Our kind of treasure.
My postdoc, Peter Garnavich, was eager to plunge into this game. Peter was a late bloomer. He had been a graduate student at MIT, then quit and worked at the Space Telescope Science Institute before going to the University of Washington for a Ph.D. He had observed exactly one supernova as a graduate student, but he seemed like a good choice for a postdoc. Peter was turning out to be far more versatile and courageous than I expected. He had done a great job with our first Space Telescope data, but in hall 1997, we weren't quite ready to say that the data required acceleration. In 1998, we had the evidence for acceleration. Now he was ready to take the next step. With Harvard graduate student Saurabh Jha, Peter looked into the problem. You needed to compute how well the two kinds of data agreed with every possible value of SiIT, and £2A. Saurabh made a plot that showed what you learned from the supcrnovac alone, and then what you gained from crossing it with the CMB data. I was stunned. When you combined the microwave background data with the supernova data, they made a bull's eye of probability. Those lines could have crossed anywhere, but the place they crossed was at = 0.3 and £2A= 0.7. We had hit the treasure! This work was published in The AsirophysicalJournal Letters in February 1998."'
The value for £2A wasn't, by itself, a powerful test—the fact that it was bigger than zero was the unique contribution of the supernova work. But the fact that the X came out at Q™ = 0.3 was something that we could compare to independent measurements of £2n.f measurements that had nothing to do with supernovae or the microwave background. Following Zwicky's lead, there was a rich literature of measurements for the dark matter of the universe. Galaxy motions in clusters, gravitational lensing, and X-ray emission were all ways to detect invisible matter from its gravitational effects. And the measurements showed £2r:i = 0.3 ±0.1. When completely independent lines of evidence converge, then you hear the ring of truth.
The story got even better at the beginning of 1999 when two balloon experiments designed to measure fluctuations in the microwave background reported their results. BOOMERANG, which had
Figure 11.2. Combining information from super novae and from fluctuations in the cosmic microwave background Zteroes in on the values for iL and ii* Courtesy of Saurabh Jha, Harvard-Smithsonian Center for Astrophysics
Figure 11.2. Combining information from super novae and from fluctuations in the cosmic microwave background Zteroes in on the values for iL and ii* Courtesy of Saurabh Jha, Harvard-Smithsonian Center for Astrophysics circumnavigated Antarctica and come back to its launching site after making 10 days of observations, and MAXIMA, another balloon experiment, both showed clean signals at the angular scale of T. What's more, the precision of these new measurements was enough to pin down the total They showed that Q = 1.00 ± 0.04. Since ti = 1.0000000000 ... is the value to which omega will be driven with exquisite accuracy by inflation, there are cheerful faces among the theorists. Inflation may not be the only model for the Big Bang, and there are variations on the inflation theme that do not produce £2=1, but this was a test the purest version of this model could have failed. It did not fail and its several authors have good reason to be pleased.
While the cosmological pieces were rapidly falling into place like the cheerful frenzy of the last minutes of completing a jigsaw puzzle, Mike Turner, head cheerleader for cosmology, was writing r« 7 v
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