Conference hydra::dejavu

225.0. "Hypercharge - the fifth force?" by MILRAT::KEEFE () Mon Oct 20 1986 10:52

Associated Press Sun 19-OCT-1986 18:10                            Fifth Force

   Scientists Challenge Fifth Force Postulation

   RIVERSIDE, Calif. (AP) - Scientists at two universities discount
the existence of a fifth force governing matter, and say temperature
changes may have distorted a 77-year-old experiment said to offer
evidence of such a force.
   However, physicist Ephraim Fischbach of Purdue University
contends he took such temperature changes into account when he
postulated the existence of a mysterious fifth force that tends to
counteract gravity over short distances.
   Physicists Shu-yuan Chu of University of California at Riverside
and Robert H. Dicke of Princeton, writing in the current issue of
Physical Review Letters, said temperature changes in the laboratory
of Hungarian physicist Roland von Eotvos could have distorted
Eotvos' experiment 77 years ago.
   Eotvos, confirming research by Galileo, determined the value of
the so-called gravitational constant - a measure of the acceleration
of objects due to gravity - by suspending weights of different
composition from the ends of a balance.
   A combination of Earth's gravity and its centrifugal force would
cause the balance to twist, and the amount of twist revealed the
gravitational constant. He obtained an accurate value for the
gravitational constant but observed discrepancies that he attributed
to limitations in his experimental apparatus.
   Fischbach and colleagues theorized a fifth force might be
responsible.
   The four known forces - gravity, electromagnetism and the strong
and weak forces that govern the structure of the atom - had been
thought to explain all matter.
   Fischback called the new force ``hypercharge.''
   Hypercharge gets its name from a characteristic of subatomic
particles, also called hypercharge. While some subatomic particles
carry an electrical charge, some also carry a hypercharge. Unlike
gravity, which pulls on objects hundreds of millions of miles apart,
hypercharge is believed to act only within a range of several
thousand yards, thus leaving the movement of celestial bodies
unaffected.
   Chu said subtle temperature changes creating ``a gentle wind''
blowing past the experiment's apparatus could account for the
discrepancy in Eotvos' results without the effect of any hypercharge.
   Because the objects on the ends of the balance are different
sizes, in order to make their weights balance, the wind itself could
twist the balance, Chu and Dicke said.
   In the same journal, Fischbach and colleagues said Eotvos'
experiments were conducted over a period of three years, making it
unlikely that a temperature difference would have had the same
effect on all experiments. They also said Chu and Dicke's
calculations fail to take all data into account.
   They note that for most materials tested by Eotvos, the twist
resulting from the temperature difference should be similar, but
when platinum is used, results are different, and that Chu and Dicke
didn't account for that.
   Fischbach's disputed theory has triggered several additional
experiments by other scientists, but results are incomplete.
   One of these other scients, physicist Riley Newman of the
University of California at Irvine, said ``both Chu and Dicke's
paper and the (Fischbach) response are valid.''
   However, he said the data for platinum is ``particularly
crucial.''
   ``But rather than raking over the coals of such an old experiment
again and again, it is better to wait until some of the data from
more modern experiments are available,'' he said.