The Star-Trek vision of cloaking devices was shown to be a physically realistic possibility by scientific research, and new researxch points to the possibility of making time invisible as well.
Scientists have already managed to make an object invisible in space, but the next big challenge is to make one invisible in time.Cornell University researchers Alexander L. Gaeta and Moti Fridman have been leading a team experimenting with this aim in mind.
Although, truth be told, they only achieved their goal for a pico-second-an unimaginably short time – their success could eventually lead to genuine cloaking devices, though more likely in the short term to better fibre-optic line security.
So-called ordinary cloaking involves scientists and engineers looking at how to make objects invisible to the eye. Using refraction is one way of doing it, this being the property through which prisms split sunlight into the rainbow colours, though the ordinary transparent prism material used to bend the light waves is replaced by scientists with meta-materials.
Engineered to have properties that not be found in nature, such as a negative index of refraction, making light rays bend totally differently, enabling scientists to use such materials to bend light rays away from objects and make them invisible, to all intents and purposes.
If light waves fail to hit an object, it will not be seen, though the cloaking of time is a different ball game, so rather than bending light waves around an object, the team slowed light down on one side, creating a “time lens”.
This works by slowing light wave-lengths and causing them to reach their destinations at different times. This effect means that by passing the light through the time lens, before passing it through a dispersal medium, they created a gap in the light.
This represented a moment in time when no wave-length of light was visible. Shorter wavelengths- violet to blue and green would be seen first, a gap, then the yellow to orange and red wavelengths, which are longer. This light is then through another medium reversing dispersal, then back through another time lens, so that the beam appeared unchanged, with no way of knowing that anything had occurred.
A really practical analogy might be the breaking of a line of cars at traffic signals, and the reforming of the line at the next junction, the idea tested by the scientists via the sending of a light pulse through the gap, at a frequency different from the reference one, that pulse almost invisible.
No practical technology yet exists to allow this phenomenon to be taken advantage of on a large scale, though the combination of this technique with the spatial invisibility research methods could make a true cloaking device a more realistic possibility in the future.