Light must travel in a straight line and at a constant
speed, or so the laws of nature suggest. Now, researchers at the University of
the Witwatersrand in Johannesburg have demonstrated that laser light traveling
along a helical path through space, can accelerate and decelerate as it spins
into the distance.
This is the first time that angular acceleration has been
observed with light, and is therefore likely to lead to new applications using
these structured light fields.