This is interesting:
Scientists have recently succeeded in doing all sorts of fancy things with light, including slowing it down and even stopping it all together. Now a team at the Ecole Polytechnique Fdrale de Lausanne (EPFL) in Switzerland is controlling the speed of light using simple off-the-shelf optical fibers, without the aid of special media such as cold gases or crystalline solids like in other experiments.
Maybe it’s because I had only one semester of physics, but the explanation seems contradictory:
Light in a vacuum travels at approximately 186,000 miles per second, but a popular misconception is that, according to Einstein’s special theory of relativity, nothing in the universe can travel faster than this speed.
This seeming paradox can be resolved because a pulse of light is actually made up of many separate frequency components, each of which moves at their own velocities. This is known as the pulse’s phase velocity. If all the frequency components have the same phase velocity, then the overall pulse will also appear to move at that velocity.
However, if the components have different phase velocities, then the pulse’s overall velocity will depend on the relationships between the velocities of the separate components. If the velocities differ, the pulse is said to be moving at the group velocity.
By tweaking the relationship between phase velocities, it’s possible to adjust the group velocity and create the illusion that parts of the pulse are traveling faster than the speed of light.
If it’s only an illusion, then how does this disprove the popular misconception that “according to Einstein’s special theory of relativity, nothing in the universe can travel faster than this speed”?
As an aside, are MSM science writers always required to tag on to the end of their articles some way this science can be practical?
One area where such an advance could be enormously beneficial is in the telecommunications industry.