New form of light discovered, proving Planck’s constant can change

Scientists have discovered a new form of light, proving that a “constant” calculation used for more than 100 years can indeed be inconsistent.

This new revelation by researchers at Trinity College Dublin (TCD) in Ireland introduces humans to light with an angular momentum that’s a fraction of Planck’s constant, as opposed a multiple of the German physicist’s calculation like all existing forms.

Angular momentum is a measure of how much a beam rotates on its own axis and serves as a valuable scale within quantum mechanics.

“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,” TCD Assistant Professor Paul Eastham said.

With Planck’s constant recognized since 1900, this new discovery, published by researchers from TCD and the CRANN Institute in the journal Science Advances, completely changes how scientists will study light.

To make their discovery, scientists tweaked a technique first discovered at the university in the 1830s by mathematician William Rowan Hamilton and physicist Humphrey Lloyd.

By sending beams through crystals using an optical filter to create screw-like structures, they created a scenario in which a photon’s angular momentum was one half of Planck’s constant.

"Our discovery will have real impacts for the study of light waves in areas such as secure optical communications,” which could, for example, result in increased bandwidth in fiber-optic cabling, said Professor John Donegan.