This particular scientific event is nothing less that revolutionary. Scientists at the University of Glasgow have for the first time been able to drag light by slowing its speed, down to the speed of sound; and then successfully sending it through a rotating crystal.
For most people, courtesy what we have studied in our school books, the speed of light is constant, but this fixed speed is only in a vacuum, such as space, where light travels at a constant speed of 3,00,000 kilometers per second or at 671million mph. Making the light from sun reach earth in approximately eight minutes.
However, when the same light travels through mediums of different levels of denseness (also called density), such as water or solids, its speed is reduced (the more dense the medium, the slower the speed), with different wavelengths (colors) travelling at different speeds.
Scientists always had the knowledge (via observation) that light can be dragged when it travels through a moving substance, such as glass, air or water – a phenomenon first predicted by Augustin-Jean Fresnel in 1818 and observed a hundred years later; but not much effort is put into the researching this phenomenon. Although it has been often repeated that, the drag happens, like when light travels through glass, movement of the glass drags the light with it too (Glass may look solid, but there are movements in it, just like water).
To conduct the breakthrough experiment, scientist tried to mimic an observation in their lab, wherein -- Spinning a window as fast as one could is predicted to rotate the image of the world behind it ever so slightly. This rotation would be about a millionth of a degree and imperceptible to the human eye.
In research detailed in the latest edition of the journal Science, and shared by Physics blog, researchers Dr Sonja Franke-Arnold, Dr Graham Gibson and Prof Padgett, in collaboration with their colleague Professor Robert Boyd at the Universities of Ottowa and Rochester, set up an experiment: shining a primitive image made up of the elliptical profile of a green laser through a ruby rod spinning on its axis at up to 3,000 rpm.
Once the light enters the ruby, its speed is slowed down to around the speed of sound (approximately 741miles per hour) and the spinning motion of the rod drags the light with it, resulting in the image being rotated by almost five degrees: large enough to be perceptible to a naked eye.
The potential of the breakthrough:
Although the scientists planned the experiment of using slow light in ruby to observe the photon drag, mainly to demonstrate a fundamental optical principle, but they find the results having the potential in many futuristic applications too. To explain this the lead researcher says: Images are nothing but information and the ability to store their intensity and phase(angle or degree) is an important step to the optical storage and processing of quantum information, potentially achieving what no classical computer can ever match.
The option to rotate an image by a set arbitrary angle presents a new way to code information, a possibility not accessed by any image coding protocol so far.
Amen! --------
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