Spacetime 'more like clear whisky than frothy beer'

Astrophysicist Robert Nemiroff of Michigan Technological University and NASA Goddard, reached this conclusion after studying the tracings of three photons of varied wavelengths that were recorded by NASA's Fermi Gamma-ray Space Telescope in May 2009. The 'Science Daily' reported.

The photons originated about 7 billion light years away from Earth in one of three pulses from a gamma-ray burst. They arrived at the orbiting telescope just one millisecond apart, in a virtual tie.

Gamma-ray bursts are short-lived bursts of gamma-ray photons, the most energetic form of light. They can originate far across the universe, and astronomers believe many are caused by giant stars collapsing, often billions of years before Earth was formed.

"Gamma-ray bursts can tell us some very interesting things about the universe," Nemiroff said.

In this case, those three photons recorded by the Fermi telescope suggest that spacetime may not be not as bubbly as some scientists think.

Some theories of quantum gravity say that the universe is not smooth but foamy -- made of fundamental units called Planck lengths that are less than a trillionth of a trillionth the diameter of a hydrogen atom.

Planck lengths are so small that there's no way to detect them, except via photons like those that make up gamma-ray bursts.

The reason the wavelengths of these photons are some of the shortest distances known to science