Can light particles be slowed? It was unthinkable in an open space. Up to now. A team of researchers from the University of Glasgow and Heriot-Watt University (UK) have succeeded in slowing down photons (light particles) in free space for the first time in history. The study has been published in the journal Science Express .
Taking into account that the speed of light does decrease subtly when passing through materials such as glass or water, until now it was considered impossible for this to happen when photons travel through open space without interactions with any kind of material .
The key to achieving this milestone in physics has been a mask that changes the shape of the light particles and slows their speed slightly. Thus, for their experiment, applying a mask to an optical beam, they verified that photons could be given a spatial structure that reduces their speed. They proved by a race against the clock with two photons, that the photon modified by the mask arrived later than the other , which confirmed that it traveled more slowly in the open medium because what the mask does is limit the maximum speed at which the photon is able to travel.
According to the work, in a distance of one meter, the photon registered a decrease in speed of up to 20 wavelengths , leaving out of any doubt that it was a figure within the margin of error of the device.
“This finding unequivocally demonstrates that the propagation of light can be slowed down below the commonly accepted figure of 299,792.458 km / s , even when traveling in the air or in a vacuum,” explains Jacquiline Romero to the Sinc agency. co-author of the study.
