|No, not “Dark Side of the Moon”
Light traveling in a vacuum moves through space-time at approximately 300,000 kilometers per second. But MUST light travel that fast? Is the speed of light a constant? Einstein said that light could be bent by a gravity well, but he didn’t ever discuss changing the speed of light. We know that light is slowed as it passes through matter, such as water, that refracts it (which is why it’s darker in the ocean as you go deeper). But if you stop light, is it still…light? Maybe.
The Optical Society’s (OSA) open-access journal Optics Express, cites researchers from France and China who embedded dye molecules in a liquid crystal matrix to throttle the group velocity of light back to less than one billionth of its top speed. The team says the ability to slow light in this manner may one day lead to new technologies in remote sensing and measurement science.*
*Retrieved August 15, 2013, from http://www.sciencedaily.com/releases/2013/08/130813201436.htm
The key to achieving a significant drop-off in speed is to take advantage of the fact that when light travels as a pulse it is really a collection of waves, each having a slightly different frequency. However, all the waves in the pulse must travel together. Scientists can design materials to be like obstacles courses that “trip up” some of the waves more than others. In order to exit the material together, the pulse must wait until it can reconstitute itself.
Other research groups have manipulated the properties of atomic vapors or crystal lattices to significantly slow light and, under certain circumstances, to temporarily “stop” it inside the medium. Bortolozzo’s team instead used a liquid crystal similar to the materials used in LCD television and computer displays that could operate in a simple setup, does not require external voltages or magnetic fields, and works at room temperature and with very low optical power. They added a chemical component that twisted the liquid crystal molecules into a helical shape and then added dye molecules that nestled in the helical structures. The dye molecules change their shape when irradiated by light, altering the optical properties of the material and hence changing the relative velocities of the different wave components of the light pulse as it travelled through. In addition, the helical structure of the liquid crystal matrix ensures a long lifetime of the shape-shifted dyes, which makes it possible to “store” a light pulse in the medium and later release it on demand.
The new possibilities that these investigations could open in the fields of remote sensing and optical storage for computer information. In fact, it may be possible to construct a “quantum computer” by using circuits of ‘stopped light’, increasing computing speed to presently unimaginable levels and storing information with light itself.