Black holes: a sharper view

By synchronizing radio telescopes, scientists move one step closer to proving their existence.

Sometimes science is like a soccer match in which a demonstration of a more effective way to play the game is more important than the final score.

That’s the way it is with recent research that’s given us the sharpest view yet of the black hole some 25,000 light years away at the heart of our galaxy. It’s also like that with a new way of looking at fingerprints that not only reveals who owns the finger but also what chemicals the finger has poked into.

Sheperd Doeleman at the Massachusetts Institute of Technology and colleagues have taken a tried and true radio astronomy technique to a new level in scrutinizing that black hole. It’s a kind of mathematical sleight of hand in which a bunch of small radio telescopes are linked and synchronized so that they act like one big instrument. Dr. Doeleman’s international research team linked four radio telescopes separated by thousand of miles to form a “virtual” instrument that acts like a single telescope 2,800 miles in diameter. The imaging power of a dish antenna that large is sharp enough to pick out “a baseball on the surface of the moon,” Doeleman says.

Actually, the observations the team reports Sept. 4 in Nature do not show the black hole directly. It’s gravity is so strong that not even light escapes if it’s inside the black hole’s so-called event horizon. This area marks the zone of no return for anything falling toward the black hole. The hole reveals itself by the radiation emitted by material falling toward or orbiting the event horizon.

By sharpening their view, the researchers were able to detect the highest density yet seen for the concentration of matter at our galaxy’s center. Doeleman calls this “important new evidence supporting the existence of black holes.”

In MIT’s announcement, Harvard University astrophysicist Avi Loeb, not a research team member, explains the observing technique’s importance. The fact that such observations are now feasible, he says, “opens up a new window for probing the structure of space and time near a black hole and testing Einstein’s theory of gravity,” which predicts black holes should exist.

At Purdue University, Demian R. Ifa and colleagues are opening a new window for viewing latent fingerprints. As any good “CSI” script will point out, latent fingerprints are just distributions of chemicals in distinctive patterns on specific surfaces. The Purdue researchers are developing a way to get important information from the nature of those chemicals in addition to what can be gleaned from looking at the fingerprint pattern itself.

They explained last month in Science how they obtain samples of the various fingerprint chemicals by an evaporation process. They weigh the samples to get the mass of each type of chemical molecule. They then can proceed to identify what chemicals are present in the print. Their early tests show they can easily detect traces of explosives or illegal drugs. With this kind of analysis, you can tell not only who left the fingerprint but what substances the suspect handled.

These simple examples illustrate an important point: Scientific progress depends heavily on how well your techniques allow you to play the research game.