Quest for the 'rubber duckie' in our galaxy

While scientists savor the thrill of new discoveries, patient nibbling at intransigent problems also has its rewards. It's paid off for researchers trying to get a handle on the mysterious object pumping radio waves from our galaxy's center. The object has tantalized astronomers for 30 years, hiding its face in dust 25,000 light years from Earth.

Last week, the National Radio Astronomy Observatory in Socorro, N.M., reported that an international team finally has measured its size. It is massive, packing the equivalent of 4 million suns into a volume that probably would fit within Earth's orbit. They believe it encompasses a black hole that, itself, would fit within Mercury's orbit. A black hole is an object that has collapsed to such a high density that not even light escapes its gravity.

The research is like "trying to see your yellow rubber duckie through the frosted glass of the shower stall," says team member Geoffrey Bower of the University of California at Berkeley.

By learning how to judge size from the way the object's radio emissions decrease as wavelengths get shorter, the team can zero in on the "duckie's" size.

Dr. Bower calls this "a big step forward" in the larger quest to determine the nature of the object and, ultimately, to measure the size of its black hole. If successful, it would be the first measurement ever of a black hole.

Meanwhile, another team of nibblers has refined the measurement of one of nature's fundamental numbers - the so-called fine-structure constant. It's a key number in the physics of electromagnetic force and radiation and determines the spectrum of light emitted by an atom.

Scientists have wondered for decades whether nature's 25 basic constants, like this one, are truly constant throughout all space and time or whether they vary. If they do vary, then our understanding of the material universe needs serious revision.

Some astronomical studies reaching deep into the universe and, hence, far back in time, have suggested that the fine-structure constant has increased slightly over the eons. But the European Southern Observatory in Garching, Germany, now reports that observations reaching even further back in time show that no such evidence exists.

An international team led by Patrick Petitjean of the Paris Observatory used data from the observatory's Very Large Telescope array at Paranal in Chile. They were able to look back 10 billion years to see how atoms emitted electromagnetic radiation when our universe was young. They found that atoms back then emitted light just as they do today.

That's a comforting thought for scientists who don't want to worry about the integrity of nature's 25 basic numbers as they pursue other scientific work. But it won't settle the question for cosmological speculators. They'll nibble away at testing constants for inconsistency because the problem has fundamental importance.

As for the black-hole hunters, the scent of their quarry is strong. They'll nibble even harder at refining the radio data from our galaxy's center until they can define the eye on that "rubber duckie."