blackholesun
Registered Senior Member
From the article:
"What is shocking is that such an effect has been observed for the first time without a great deal of attenuation, amplification or distortion of the pulse. It appears as though energy has, in fact, travelled faster than light.
Of course, this is not the case. The effect observed at NEC only works in the presence of an amplifying medium, i.e. a medium that stores energy. In this case the energy is stored in the pump-laser beams. The caesium atoms are prepared in a state that allows them to transfer energy from these beams to the signal beam. The faster-than-light propagation occurs because the pump beams preferentially amplify the leading edge of the incident pulse, lending power to the signal and being repaid by absorbing some of the energy in its trailing edge. (It is important to note that even the dramatic 60 ns advance is only one fiftieth of the width of the pulse.) This is exactly analogous to the intuitive explanation of normal dispersion, except that in this case the atoms temporarily amplify the light pulse rather than absorb it. "
And:
"Although relativity emerges unscathed from these experiments, our understanding of exactly which velocities are limited (or not) by c continues to evolve. And even though neither energy nor information is transmitted faster than light in experiments like the one at the NEC, it has already been proposed that the effects may one day be useful in compensating propagation delays in electronic systems."
So relativity prevails and this only seems to work in controlled environments under the proper conditions in a prepared medium.
"What is shocking is that such an effect has been observed for the first time without a great deal of attenuation, amplification or distortion of the pulse. It appears as though energy has, in fact, travelled faster than light.
Of course, this is not the case. The effect observed at NEC only works in the presence of an amplifying medium, i.e. a medium that stores energy. In this case the energy is stored in the pump-laser beams. The caesium atoms are prepared in a state that allows them to transfer energy from these beams to the signal beam. The faster-than-light propagation occurs because the pump beams preferentially amplify the leading edge of the incident pulse, lending power to the signal and being repaid by absorbing some of the energy in its trailing edge. (It is important to note that even the dramatic 60 ns advance is only one fiftieth of the width of the pulse.) This is exactly analogous to the intuitive explanation of normal dispersion, except that in this case the atoms temporarily amplify the light pulse rather than absorb it. "
And:
"Although relativity emerges unscathed from these experiments, our understanding of exactly which velocities are limited (or not) by c continues to evolve. And even though neither energy nor information is transmitted faster than light in experiments like the one at the NEC, it has already been proposed that the effects may one day be useful in compensating propagation delays in electronic systems."
So relativity prevails and this only seems to work in controlled environments under the proper conditions in a prepared medium.