Space-Time Loops May Explain Black Holes

Physics cannot describe what happens inside a black hole. There, current theories break down, and general relativity collides with quantum mechanics, creating what’s called a singularity, or a point at whichthe equations spit out infinities.

But some advanced physics theories are trying to bridge the gap between general relativity and quantum mechanics, tounderstand what’s truly going on inside thedensest objects in the universe. Recently, scientists applied a theory called loop quantum gravity to the case of black holes, and found that inside these objects, space and time may be extremely curved, but that gravity there is not infinite, as general relativity predicts.

This was the first time scientists have applied the full loop quantum gravity theory to black holes, and the results were encouraging, researchers said.

A black hole is created when a huge star runs out of fuel for nuclear fusion and collapses under its own gravity. The star’s outer layers are expelled, and its core falls in on itself, with the pull of gravity becoming ever stronger, until what’s left is the core’s mass condensed into an extremely small area. According to general relativity, this area is a single point of space-time, and the density there is infinitely large — a singularity.

But most scientists think singularities don’t really exist, that they’re just a sign that equations have broken down and fail to adequately describe reality. Loop quantum gravity appears to be an improvement on general relativity in describing black holes because it doesn’t produce a singularity.

The idea is based on the notion of “quantization,” which breaks an entity up into discrete pieces.Whilequantum mechanics says atoms exist in quantized, discrete states, loop quantum gravity posits that space-time itself is made of quantized, discrete bits, in the form of tiny, one-dimensional loops.

“The loop means the fundamental excitations of space-time themselves are one-dimensional in nature,” said Jorge Pullin, a physicist at Louisiana State University, who co-authored the new study with Rodolfo Gambini of the University of the Republic in Montevideo, Uruguay. “The fundamental building block is a loop, or network of loops. For a visual image, think of a mesh fabric.”

Source: http://www.space.com/21903-black-holes-explained-space-time-loops.html