Breakthrough: Scientists Have Slowed Down Light By Twisting It! Light, in all its aspects, has captivated the attention of physicists for decades and decades now, specially in terms of its speed. Well, guess what. A team of researchers from the National Institute of Physics of the University of Philippines have just discovered a way to slow it down by causing it to twist! Their findings are published in Scientific Reports.
One of the laws of physics dictates that light travels at a constant speed in vacuum at 299,792,458 m/s; this constant is one of the fundamental ones in physics. Otherwise, light will travel much slower if it passes through a medium other than vacuum, like water. Making it go slower, on the other hand, is thought to come with advantages when it comes to optical computers and telecommunication systems. However, the methods currently known to make it slow down (by making it pass through other media) do not cater for an accurate transmission of information. This is why the findings of the team from the University of Philippines’ National Institute of Physics are thought to be invaluable.
The researchers were able to achieve an unprecedented feat: they made light slow down by making it twist in a different way. Their procedure involved beams of light known as Laguerre-Gauss (LG) beams (currently used in telecommunication systems) which carry orbital angular momentum, or OAM; the latter is a quantity denoting the extent of light rotating. It is to be noted that each light beam has its specific OAM. This is what the team was able to manipulate in LG beams: they changed their OAM. This alteration was done without touching the teams or interfering with them.
The scientists were, thus, able to alter the path of light so that the light would take longer to reach its destination.
Furthermore, the researchers estimated the amount of time by which each LG beam could be slowed down.
These findings could be put to good use in the world of technology: if the beams can be slowed down, and their rate can be controlled, it might become easier to manipulate the flow of information like never before. Telecommunication systems might be made more efficient.
Does this mean that the physicists have changed the speed of light? No, of course not. They only managed to make it twist in such a way that it took more time to reach its destination. But, it could mean that the speed of light is not that much of a constant as it is thought to be.