Last April Henry Hill, 48, a physics professor at the University of Arizona, presented a paper at the Royal Astronomical Society in Ireland. In it he discussed some solar measurements taken by his astrophysicist team in Tucson, Ariz. Ordinary stuff? Hardly. If he is proven right, Hill will have undermined one of the building blocks of modern physics: Albert Einstein's general theory of relativity. "The probability is 95 percent," Hill observes, "that Einstein's theory was wrong."

Since then Hill may be forgiven if he feels like a cross between the Grinch who stole Christmas and Roger Maris when he broke Babe Ruth's record. For having the temerity to challenge such a revered figure as Einstein, Hill has been subjected to everything from crank letters to criticism framed in the most decorous of academic terms. Among the skeptics is Robert Dicke, a leading relativity scholar at Princeton and Hill's former mentor. "My feeling is that to disprove Einstein's general theory of relativity you have to have a really solid demonstration," cautions Dicke. "Most of us agree that [Hill's] is not a sufficiently strong case to throw out Einstein's general theory."

That theory was first widely propounded in 1916, and it focused on gravity. (The special theory of relativity, which concerns time, light and mass and includes Einstein's famed E = mc[sup]2 formula, is not relevant to Hill's study.) Sir Isaac Newton had argued in the 18th century that gravity was an attractive force between celestial bodies. Then Einstein advanced the astonishing idea that gravity occurred when a massive object distorted space. A major proof of Einstein's theory involved a peculiarity in the planet Mercury's orbit, which he attributed to the distortion of space created by the great mass of the sun. Central to the proof was an assumption that the sun is perfectly spherical. But Hill's observations showed that the sun is not perfectly round, a discrepancy that Hill has said may be "the Achilles tendon of the general theory."

Hill now believes that the core of the sun rotates some six times faster than its surface, which causes a slight flattening of the sun at its poles and a bulging at its equator. This bulge, Hill argues, means that Einstein's predictions were wrong and that the correct measurements indicate that general relativity is most likely not true. "We didn't set out to prove Einstein was wrong," he insists of his findings. "We set out to measure the shape of the sun, and found it to be oscillating. That meant that all concepts about a stable sun had to go down the tube."

There have been many previous attempts to disprove Einstein. Some were frivolous, like Nazi Germany's effort to discredit his theories as "Jewish science." Others involved years of serious research. Ironically, perhaps the strongest challenge before Hill's was advanced in 1967 by Princeton's Robert Dicke himself, in collaboration with Dr. Mark Goldenberg. But it never shook the faith of other physicists in general relativity. "If it hadn't been for Dicke, we wouldn't be where we are today," Hill says. "He could have made the discovery just as easily as we did. Fate chose otherwise."

In the present controversy, no one questions Hill's credentials. He has taught physics at Arizona since 1966. Raised in Texas City, Texas—his father was a machinist, his mother an elementary school teacher—Hill dropped out of high school as a senior to enroll at the University of Houston in engineering, then went on to take his Ph.D. in physics at the University of Minnesota. At 23, he joined the prestigious physics department at Princeton, not far from Einstein's old office at the nearby Institute for Advanced Study. He and wife Louise married in 1954; they have three children aged 13 to 21.

Hill doesn't apologize for stirring up a controversy. "A lot of people are going to run us through the mill over the next few years, and that's good," he shrugs. "If they had accepted our findings without question, that wouldn't have been good science."

In fact, it may be years, Hill admits, before his challenge to Einstein's theory is verified. A major problem is the difficulty of making accurate measurements of conditions on the sun. But if and when his findings are accepted, Hill's sense of triumph will probably be as tempered as was Einstein's when he finally overturned Newton's long-accepted theory of gravity. When the proof seemed certain, Einstein made his announcement. Then he wrote in his journal: "Newton, forgive me."