Holy quantum singularities! Thanks to new calculations by Hubble Fellow and CAS Institute for Astrophysical Research associate Simon Portegies Zwart and a Drexel University colleague, physicists will soon be able to detect the strong gravitational waves produced by colliding pairs of black holes. In addition, as they track these waves, the scientists will be providing the first confirmation of Einstein's general theory of relativity.
For decades, gravitational waves have been known only indirectly to physicists, who had theorized that whirling pairs of neutron stars -- the dense remains of massive stars after a supernova explosion -- create ripples in the four-dimensional fabric of space and time. According to Einstein, this action sends out a weak signal of gravitational waves.
Black holes form when the core of the most massive stars collapse into a "singularity," a point of zero volume and infinite mass from which nothing, not even light, can escape. According to Einstein's equations, space-time is warped around black holes more strongly than anywhere else in the universe because of their immense gravitational fields.
Portegies Zwart and his colleague realized that in globular clusters, which can contain millions of stars, individual black holes fall to the middle because of their great mass. Once there, the black holes attract one another gravitationally and pair off, forming binaries.
Until now, astrophysicists have believed that black hole pairs were so rare that they would be almost impossible to detect, but the new calculations indicate that detectable mergers of black holes could be as much as a thousand times more common than the neutron stars astronomers had planned to study.
Scientists in Louisiana and Washington will test this theory next year with a new $350 million gravitational-wave observatory.
"Because gravitational waves are predicted by Einstein's theory of general relativity, physicists would hail their detection as a major coup," says Portegies Zwart. The study will shortly be published in Astrophysical Journal Letters.
Doing more harm than good. In July 1999 new federal regulations governing the use of physical restraints in hospitals that participate in Medicare and Medicaid programs came into effect, coinciding with a spate of news stories about patients dying while being restrained by physical devices and drugs used by doctors to control both physical movement and behavior. According to SPH Professor of Health Law George Annas, the new regulations are a step in the right direction, but are fuzzy on patients' rights.
"The new rules do not make it clear enough that competent patients have the right to refuse any medical treatment, even to save their lives, and that the use of restraints can never be justified as a means of forcing treatment," he says.
The original phrasing of the new regulations stated that restraints should be used "as a last resort." Later it was changed to "when other less restrictive measures have been found to be ineffective."
Annas thinks that this change was a mistake, and he worries that the absence of a clear statement that restraints can be applied only to incompetent patients leaves the regulations open to potentially dangerous misinterpretation. "They were right to not see the use of restraints as standard medical procedure," he says, "but were wrong to back down from the clearer, more definitive phrasing."
Annas believes that the only justification for the use of restraints is to prevent patients from physically harming themselves or others. Even then, he notes, they should be used for the shortest time possible and with the least amount of restriction.
Also, a competent adult should never be forced to undergo treatment. "If a patient refuses to talk to a physician or undergo treatment, that doesn't mean she or he is incompetent," he adds.
Annas' paper was published in the October 28 New England Journal of Medicine.
Briefs" is written by Joan Schwartz in the Office of the Provost. To read
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