London, Feb 2: A group of radio astronomers have begun looking for signals from small, exploding black holes, which if found, could provide the best evidence yet for extra dimensions beyond the four that we know of.

According to a report in Nature News, the Universe as we see it is made up of three dimensions of space and one of time, but some theories predict that many more dimensions exist beyond the ones we experience.

In particular, the string theory, which suggests that the Universe is composed of tiny, vibrating 'strings', suggests that several extra dimensions might exist beyond our own.

To date, observations have failed to turn up these dimensions, and most theorists suspect that if the dimensions do exist, they are 'curled up' in tiny closed loops around a billionth of a nanometer (10-18 m) in size.

But now John Simonetti and colleagues at Virginia Polytechnic Institute and State University in Blacksburg are investigating another way to look for these dimensions — in the explosions of 'primordial' black holes.

Formed in the earliest days of the Universe, primordial black holes are microscopic in size, despite having the same mass as a small mountain. Because of their small size, the holes are all but impossible to spot directly. Still, some experts believe that they can produce a unique radio signature.

Like all black holes, primordial black holes undergo 'evaporation', a process that causes them slowly to lose their mass. As they shrink, they evaporate more quickly, and theorists predict that their ever-accelerating evaporation might lead to a sudden explosion.

In a new twist, the research team has speculated that an extra spatial dimension might trigger a black hole to blow up.

“A primordial black hole would initially be bigger than the curled-up extra dimension,” said Simonetti. “But as it evaporates, it would get closer and closer to the scale of the dimension,” he added.

According to Simonetti, eventually, the black hole will begin to be stretched around the dimension, something like a rubber band.

“When it gets evaporated enough, the hole will suddenly 'snap' into the tiny dimension, triggering an explosion,” he said.

The blast would be smaller than those predicted from normal evaporation, but scientists believe they still should be detectable as radio waves.

Using an 8-metre antenna array in North Carolina and a second array under construction in Virginia, his group hopes to look for exploding primordial holes up to about 300 light years away. (ANI)