A long-standing mystery about the universe - we don't see equal amounts of matter and corresponding antimatter - may have been solved with the discovery "left-handed" magnetic fields existing throughout the cosmos, researchers say.

At the birth of the universe, the Big Bang should have produced particles of matter and antimatter in roughly equal numbers, which should then have quickly annihilated each other, leaving no matter at all.

Yet matter is everywhere, and antimatter is conspicuous by its almost total absence - a puzzle that researchers call one of the greatest unsolved mysteries of physics.

In 2001 a researcher at Arizona State University, Tanmay Vachaspati, offered a theoretical solution, suggesting that such annihilation did take place but because of a natural quirk in physics immediately after the Big Bang, the process was biased toward matter, leaving antimatter the loser.

As matter and antimatter particles met in mutual annihilation, he proposes, they would have created monopoles and antimonopoles, particles with just a single magnetic pole, north or south, which when they in turn destroyed each other created more matter and antimatter - but with a greater chance of matter.

There should be evidence of that matter "bias" still existing in the universe today, Vachaspati says, in the form of helical magnetic fields, the remnants of the monopoles that dominated in the annihilations.

And they should be left-handed, as evidence of their monopole origins, rather than right-handed, which would indicate antimonopoles winning out, he says.

Vachaspati and his fellow researchers looked for evidence in gamma-ray data from NASA's Fermi space telescope.

As gamma rays spread through the cosmos, if helical magnetic fields permeate the universe the rays should shows signs of being bent by those fields.

That's what the researchers, writing in the Monthly Notices of the Royal Astronomical Society, say they found - and the bending suggested those fields are left-handed, signs of the ascendency of matter over antimatter.

"What we found is consistent with them all being left-handed," says Vachaspati.

The chance of what they observed in the Fermi data occurring by chance is less than 1 percent, and "that's being conservative," he says.

Still, what they found didn't exactly match what they'd theorized, they acknowledge; in particular, the "twists" in the helical magnetic field are somewhat larger that what was predicted.

"So there is some mystery there," says Vachaspati, adding that additional data from Fermi in the coming months could help answer some remaining questions.