Physicists Just Discovered a New Form of Light

Physicists have observed a new form of light, and it could totally change the way we understand the electromagnetic spectrum. 

Light is one of the most well-studied things in physics, but it's clear that it still holds some surprises. 

One of the measurable properties of light is called angular momentum, which measures how quickly a beam of light rotates. Previously, physicists thought the angular momentum could only be a multiple of a number called Planck's constant. Now, researchers have observed a new form of light with an angular momentum of just half Planck's constant. 

An unexpected angular momentum value might not sound like a big deal, but the implications are pretty huge.

"What I think is so exciting about this result is that even this fundamental property of light, that physicists have always thought was fixed, can be changed," physicist Paul Eastham said in a statement.

The research is published in the journal Science Advances. 

What is angular momentum? Simply put, angular momentum measures how much a beam of light is rotating.

"Angular momentum measures how much something is rotating," physicist John Donegan said. "For a beam of light, although traveling in a straight line it can also be rotating around its own axis. So when light from the mirror hits your eye in the morning, every photon twists your eye a little, one way or another."

This is a well understood concept in physics, but until now, physicists didn't think it was possible to have light with an angular momentum value less than Planck's constant.

The experiment: The researchers passed a beam of light through a set of crystals that compressed it into a rotating, hollow cylinder. 

Usually a phenomenon called "quantum effects" causes angular momentum to fluctuate a little, but it always stays a whole number. So when the physicists measured the angular momentum of this beam of light, they were surprised to discover a value half that of Planck's constant. 

We'll need more research before we can start harnessing this new form of light, but it might someday lead to faster and more secure internet connections.

"Our priority is to see what the implications of this are for the science — what else might light do that follows from this," Eastham told Mic in an email. "It's always hard to speculate about potential uses as they're years away. But as almost all our telecommunications is based on light, and we're exploring these basic properties of light, there could be uses there."