Word: freedman
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Dates: during 1990-1999
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...also pays to listen to Freedman. She's a highly respected observational astronomer, and so are the 13 others on her space-telescope team. Moreover, theirs is only the latest in a series of measurements that point to a relatively young universe. Just a month before these results appeared in the journal Nature, two other sets of astronomers came out with their own young-universe observations. And while a handful of studies have emerged over the past few years arguing instead for an older cosmos, many more have converged on a younger age. The Freedman team's observations are considered...
...CRISIS: "You can't be older than your ma," quips Christopher Impey of the University of Arizona's Steward Observatory. Sounds obvious, maybe, but if Freedman and her colleagues are right about their space-telescope observations, it would seem that the universe hasn't caught on to this bit of common sense. The most straightforward interpretation of their data implies that the cosmos is 12 billion years old, max. But experts insist that the oldest stars in the Milky Way have been around for at least 14 billion years. "They could quite easily be several billion years older than that...
...observations were moved to the head of the Hubble schedule, and by July, Freedman was looking at a pattern on her computer screen that was as familiar as the face of an old friend. "Boom!" she remembers. "All of a sudden there was this glorious Cepheid light curve, as beautiful as any that have ever been measured." By the end of the observing run, Freedman and her colleagues found 19 more, enough to peg M100's distance at some 56 million light-years from Earth...
...calculation gave the astronomers the distance to Virgo, and they used that number in turn to estimate the distance to the Coma cluster of galaxies, about five times as far away. Coma, finally, is far enough out that it's a reliable indicator of the Hubble Constant. Based on Freedman's analysis, the Constant comes in at 80, indicating a universe between 8 billion and 12 billion years...
While most astronomers take these numbers very seriously-along with the cosmic paradox they imply-Allan Sandage, Freedman's grumpy colleague down the hall, is having none of it. He doesn't quibble with her measurement of the distance to M100, but insists that the analysis breaks down after that. Like most astronomers, Sandage has his favorite method of gauging the relative distance of galaxies. He finds a type of supernova-an exploding star-and compares supernova brightnesses from one galaxy to another. He claims, as he has done for more than 20 years, that the Hubble Constant is lower...