Tiny black holes may be detonating like time bombs all over our cosmic backyard, according to a story in New Scientist magazine.

The speculative idea, which has not gained widespread support among other scientists, might explain a particular class of short energy bursts observed on Earth.

Gamma-ray bursts are huge releases of energy that can for a few seconds outshine everything else in the universe. They can come from any part of the sky, and astronomers have long assumed they originate at the edges of the universe.

But a handful of the thousands of these bursts last less than 100 milliseconds, according to David Cline and his colleagues of the University of California in Los Angeles. These short gamma-ray bursts seem to come from an area concentrated toward one particular spiral arm of our Milky Way Galaxy, the researchers told the magazine.

Cline suggests they are the detonation of microscopic black holes formed in the Big Bang, which most astronomers believe was the beginning of the universe. If the idea is right, billions and billions of relatively nearby, primordial black holes are just waiting to explode.

Some may exist just beyond the orbit of Pluto, based on the math.

But there is little danger, the researchers say. "One would have to go off closer than the Sun to affect the Earth," Cline said.

Other astronomers expressed caution over the whole idea. Roger Blandford of the California Institute of Technology in Pasadena said he was not convinced, but he added that the idea should be testable.

Said Sir Martin Rees of the University of Cambridge: "The idea isn't completely mad."

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