Warps in space, time are detected Distortion: Scientists find strong evidence that massive, fast-spinning bodies twist space-time like a tornado.

November 07, 1997|By Frank D. Roylance | Frank D. Roylance,SUN STAFF

Warps in space and time -- once safely caged inside the worlds of science fiction and theoretical physics -- appear to be mind-bending realities lurking in our own galaxy.

Two teams of scientists -- one Italian, one American -- told a high-energy astrophysics conference in Colorado yesterday that they have found rapidly spinning neutron stars and black holes that appear to be "dragging" space and time around them, like cows and silos swept up by a tornado.

Although the space-time distortions would not be perceptible to the crew of a space ship cruising near the black hole, the scientists said, they can be detected from a distant vantage point like Earth's.

Called "frame dragging," the phenomenon was predicted nearly 80 years ago by Austrian scientists as an inevitable consequence of Albert Einstein's general theory of relativity.

But it had never before been detected.

Now, through a combination of mathematical calculations and direct observations of "wobbling" X-ray emissions from exotic objects in the Milky Way, the astronomers believe they have seen it.

"It's certainly not conclusive. But the agreement between theory and our observations makes it very suggestive that this is JTC probably due to frame dragging," said Wei Cui, a research scientist at the Massachusetts Institute of Technology.

Also on the U.S team are Wan Chen of NASA's Goddard Space Flight Center, in Greenbelt, and Shuang N. Zhang, of NASA's Marshall Space Flight Center in Alabama.

The findings were reported to the High Energy Astrophysics Division of the American Astronomical Society, meeting this week in Estes Park, Colo.

According to Einstein's theories, space, time, mass and gravity are all interrelated, tightly bound by laws revealed through complex mathematics.

Many of the consequences suggested by Einstein's work boggle the imagination and clash with everyday human experience -- such as the slowing of time near massive objects or aboard speeding spacecraft.

But decades of scientific observations have confirmed more of Einstein's predictions, including the existence of black holes.

"I'm not saying we should blindly believe anything until it's proved," said Cui (pronounced SWEE). "But as the evidence really starts to accumulate, at some point you have to ask, 'What is the likelihood that this theory is wrong?' "

Extrapolating from Einstein

In 1918, Austrian physicists Josef Lense and Hans Thirring took Einstein's work and predicted that a moving massive object would drag space and time with it.

Some have suggested that this "Lense-Thirring Effect" is analogous to the effect of a moving electric current, which creates a new, invisible but detectable force around it -- a magnetic field. That effect, once recognized, led to the invention of electric motors.

Similarly, they said, anything that has mass, and moves, will distort space-time around it. The greater the mass, or the faster it moves, the larger and more easily detected the warping becomes.

"I'm distorting space around me, but it's so small it's undetectable," Cui said.

The Earth, too, is distorting space and time as it spins and moves along its orbit. NASA is preparing to launch a satellite in 2000, called Gravity Probe B, designed to detect that distortion for the first time.

For now, astronomers must look for the effect in the most massive and fastest-moving objects they can find.

The Italians, led by Luigi Stella, of the Astronomical Observatory of Rome, and Mario Vietri, of the Third University of Rome, focused their search on neutron stars spinning at hundreds or thousands of revolutions per second -- up to one-third the speed of light.

These objects are more massive than the sun, but too small to become black holes.

They have collapsed into extremely dense objects just a few miles across.

They are visible because they are stripping matter from normal companion stars. As that matter spirals into the neutron star, it heats to temperatures of several million degrees, emitting gushers of X-rays.

Stella and Vietri measured the movement of those X-ray sources using NASA's Rossi X-ray Timing Explorer satellite.

They detected a "wobble" with a frequency that matched mathematical predictions for the effects of frame dragging.

The American team noted the Italians' results and went looking for similar effects near rapidly spinning black holes.

(Black holes are the remnants of huge stars that have exhausted their fuel and collapsed into extremely dense objects, with gravity so powerful nothing that comes near can escape, even light.)

The black holes they studied are seven to 30 times more massive than the sun, but they have collapsed into objects just 30 miles to 125 miles across.

They can't be seen directly either. Like neutron stars, their sizes and masses are calculated by measuring how fast their visible companion stars are orbiting around them and how wide that orbit is.

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