It's not everyday that we discover something fundamentally new about light. In fact, it's an area of research that has been considered mostly complete. But researchers from Trinity College Dublin (TCD) could change that; they recently measured the angular momentum of photons at a fraction of what was previously believed possible, according to Ireland's National Public Service Broadcaster.

Angular momentum is one characteristic of a beam of light that measures how much it's rotating around its own axis. What's important about this is that scientists have long believed the angular momentum of all forms of light ought to be measured as a multiple of Planck's constant (which is the physical constant that sets the scale of quantum effects).

To discover that light's angular momentum can be measured in fractional increments of Planck's constant essentially opens up strange quantum possibilities about the behavior of light. These strange properties occur when photons are analyzed in two dimensions instead of three.

"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," said assistant professor Paul Eastham from TCD's school of physics.

Although it has long been established that new quantum states can form when electrons are placed in reduced dimensions, this is the first time something similar has been shown about photons. The finding could lead to new breakthroughs in fields like optical communications.

We often speak of "seeing the light" when we understand something clearly, so it's extra illuminating when light is shone on light itself. It's fun to think that there are still some mysteries we've yet to fully grasp, even when it comes to something as fundamental as light.