The Wonder of It All

Knowledge, it has been said, is like a circle. What is known is inside, and what is unknown is outside. The larger the diameter of this circle of knowledge, the greater its circumference. And the greater its circumference, the more the circle borders on the unknown. Every time a question is answered, new questions are raised that people didn’t even know were questions before. There is no end. Knowledge is infinite and unbounded.

So it should not be surprising that recent reports challenge some basic assumptions of modern physics. Mind you, 20th-Century physics has hardly been a stable body of knowledge in the first place. Physicists have been much better able to gather data than to put it all together in a consistent, coherent theory that can both explain and predict. But progress has been made. Two books were published last year that asserted that physics was on the verge of a complete explanation of the universe.

One of the tenets of physics has been that there are four basic forces in the universe--gravity, electromagnetism and the so-called strong and weak forces of nuclear structure. Prodigious efforts have been made to find a Grand Unified Theory that would demonstrate that all four forces are the same.

Now comes word from a team of physicists led by Ephraim Fischbach of Purdue University that there may be a fifth force in the universe that acts against gravity and causes objects to fall at slightly different rates. This force, which they call hyper-charge, would contradict the findings of one ofthe most famous stories in the history of science: Galileo’s dropping cannon balls from the Leaning Tower of Pisa to show that (air resistance aside) all objects fall with the same acceleration regardless of weight or material.

Hypercharge is supposed to be very small and to work only on objects that are fairly close to each other (up to about 600 feet), which would explain why it has not been observed before. We called our friend Richard Feynman, the great theoretical physicist at Caltech, and asked what he thought of this theory. Not much, he said. The new paper by Fischbach and his colleagues is based on experimental data collected in 1909 by Roland von Eotvos. It is not clear, Feynman said, that variations in Eotvos’ measurements of gravity result from an unknown fifth force. They could just as easily have been caused by variations in the conditions of Eotvos’ experiments. Many more experiments need to be done, he said.

But Feynman had no fear that the existence of a fifth force would damage the structure of physics. Science is a process of finding out the truth, he said, and the process is as important as the results. Far from being a stumbling block to a Grand Unified Theory, a fifth force could help scientists refine their ideas and choose among competing models.

In the meantime, it is reasonable to insist on more evidence before rewriting the physics texts.