Physicists Slow Down Light by "Twisting" It

Tuesday, 31 May 2016 - 1:45PM
Tuesday, 31 May 2016 - 1:45PM
The speed of light is one of the most important constants in physics, and it remains unchangeable. But in spite of this, scientists have just found a way to "slow down" light, by twisting photons so they take longer to get to their destination.

According to the laws of physics, the speed of light, denoted by c, remains constant while traveling through free space. On Earth, light travels at a different speed when it's slowed down by barriers like glass or even air, but the speed within a vacuum (299,792,458 m/s) always stays the same. But according to this new study, published in Nature, light is "by nature dispersive," even while traveling through free space. As a result, physicists have found a way to effectively slow light down.

For the study, the researchers used a type of light called Laguerre-Gauss (LG) beams, which carry Orbital Angular Momentum (OAM), a quantity that measures how much light is rotating. The scientists demonstrated that they were able to indirectly change the OAM, thereby increasing the amount that the light rotated in its path, which caused the light to move slower towards its destination.

To be clear, this doesn't mean they have found a way to "change" the speed of light; the light is still moving at speed c, but since it's taking a less direct path towards its destination, it takes longer to get there. And since the researchers were able to predict how much the light beams would slow down, LG beams can potentially be used for a variety of applications, particularly when it comes to transmitting information over optical fibers. This research could allow for scientists to much more accurately control the flow of information that is transmitted via light.

Via Science Alert
Image Credit: RX Photography

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