Analysis of Falling Objects : Fifth Fundamental Force May Govern All Matter
Generations of science teachers have apparently been wrong.
A classic paradigm taught to students from elementary school on up is that any two objects, such as a lead weight and a feather, will fall to Earth at the same speed, if the effects of wind resistance are discounted.
New analysis suggests, however, that--contrary to logic--the feather would actually drop slightly faster than the lead.
That conclusion rests on the apparent discovery of a fifth fundamental force governing matter. The four known forces--gravity, electromagnetism and the strong and weak forces that govern the structure of the atom--are thought to explain all things in nature.
The hypothetical fifth force, called hypercharge by its discoverers, is much weaker than the other four forces and acts over very limited distances, perhaps no more than 600 feet. It thus has little effect on the physical laws that govern everyday life, including the movement of celestial bodies.
The discovery of hypercharge could, however, have a major effect on the efforts of theoretical physicists to develop a grand unified theory that would explain the interaction of all known forces.
What is perhaps most unusual about the supposed force is that it was not discovered with the use of giant accelerators or any of the other sophisticated tools of modern physics. Instead, its existence was deduced from a re-examination of results originally reported in 1922.
Its existence was again suggested in the Jan. 6 issue of the journal Physical Review Letters by a team headed by Ephraim Fischbach, who is on sabbatical from the University of Washington in Seattle.
The team undertook the study, Fischbach said in a telephone interview, because it observed “something funny” in certain results obtained by them and by other investigators.
Fischbach and S. H. Aronson of Brookhaven National Laboratory, for example, were studying the difference between the masses of two elementary particles known as k mesons. They found that the difference in mass depends upon the speed of the particles.
“This difference could not have arisen from any known force,” Fischbach said.
Similarly, Australian physicist Frank Stacey had been measuring the so-called Newtonian constant, a supposedly invariant characteristic of gravity. Stacey found that the value of the constant obtained in a deep mine was not the same as the value obtained on the Earth’s surface.
Again, this difference could not be explained using known forces.
Series of Experiments
Fischbach and his colleagues decided to re-examine a classic paper published by Hungarian physicist Roland von Eotvos. The paper details a series of experiments, conducted over two decades, in which Eotvos and his colleagues had--in a roundabout manner--compared the speeds at which objects would fall in a vaccuum.
Eotvos and his colleagues had noticed slight differences in the speeds but had believed that those differences resulted from limitations of their equipment. Their dismissal of the discrepancies led to the conventional interpretation that all objects fall at the same rate.
Fischbach’s re-examination showed, however, that those slight differences in speed were real and that they could be explained by hypercharge.
“Hypercharge is similar to electromagnetism and gravity,” Fischbach said, “in that it acts over (relatively large) distances,” up to about 600 feet. The strong and weak forces, in contrast, act over microscopic distances comparable to the size of an atom.
Hypercharge has a strength only about a hundredth that of gravity, which was previously considered to be the weakest known force, according to Fischbach. It also is a repulsive force that varies from chemical element to element. Iron has the greatest hypercharge, Fischbach said, and elements above and below iron in the periodic table show declining amounts of hypercharge. Hydrogen, the lightest element, has the least hypercharge.
Minute Differences
A lead weight, for example, thus has relatively high hypercharge and is more repulsed by the Earth than an organic feather, which has relatively low hypercharge. The net effect is that, in a vacuum, the feather should fall slightly faster than the lead weight.
For a 30-foot drop, the difference in falling times would be measured in billionths of a second.
Fischbach’s paper has met mixed reviews. The theory, according to Robert Dicke of Princeton, a leading expert on gravity, is “one of those revolutionary things which, if right, has great importance. But you have to be very careful with revolutions.” Nonetheless, Dicke said, “I can’t pick any holes in the analysis.”
Like other physicists, however, Dicke would like to see the experiments conducted under more modern conditions, and Fischbach is planning to do so as soon as possible.
The existence of a fifth force could, in Dicke’s words, have “great impact” on theoretical physicists who are trying to develop a grand unified theory, or GUT, that would explain the interactions of matter.
Physicists have been attempting to develop a GUT since Albert Einstein broached the subject in the early 1900s, but they have met with little success.
The introduction of a fifth force seemingly would make their task more difficult. But it also might make it easier.
Proton Drawback
One of the main drawbacks of existing GUTs, according to UCLA physicist John Cornwall, is that they all require protons to decay or break down over time.
“But the embarrassment of GUTs,” said Cornwall, “is that protons don’t decay.”
A few scientists have thus speculated that there may be a fifth fundamental force that would act to stabilize the proton and prevent its decay. That force, Cornwall said, would be very weak and would be analogous to electromagnetism in that like particles would repel each other.
That force sounds suspiciously like hypercharge.
