• Corpus ID: 119255331

Non-invariance of the speed of light in free-space

  title={Non-invariance of the speed of light in free-space},
  author={Nikolai I. Petrov},
  journal={arXiv: Optics},
  • N. Petrov
  • Published 22 February 2019
  • Physics
  • arXiv: Optics
A plane monochromatic wave propagates in vacuum at the velocity of c. However, wave packets limited in space and time are used to transmit energy and information. Here it has been shown based on the wave approach that the on-axis part of the pulsed beams propagates in free space at a variable speed, exhibiting both subluminal and superluminal behaviours in the region close to the source, and their velocity approaches the value of c with distance. Although the pulse can travel over small… 

Figures from this paper



Observation of negative impulse velocity in free space

Since the 1983 definition of the speed of light in vacuum as a fundamental constant with the exact value of 299792458 m/s the question remains as to what apart from the wavefront travels at that

Space-time profiles of an ultrashort pulsed Gaussian beam

By using a different initial value from the previous treatments, we reveal that the pulsed Gaussian beam in free space can be expressed as a simple wave packet along with the complex time, which

Observation of Superluminal Behaviors in Wave Propagation ”

Mugnai et al. [1] have reported an experiment in which microwave packets appear to travel in air with a speed substantially greater than c, the normal speed of light in vacuum. The packets consist of

Spatially structured photons that travel in free space slower than the speed of light

This work highlights that, even in free space, the invariance of the speed of light only applies to plane waves, and shows a reduction in the group velocity of photons in both a Bessel beam and photons in a focused Gaussian beam.

Evanescent and propagating fields of a strongly focused beam.

  • N. Petrov
  • Physics
    Journal of the Optical Society of America. A, Optics, image science, and vision
  • 2003
It is shown that the amplitude of E(ev) decays as exp(-r/w(a)) in the near-field region and that evanescent waves do not contribute to the far field in the forward direction as they do in the transverse directions theta = pi/2.

Superluminal Light Pulse Propagation at a Negative Group Velocity

Anomalous dispersion cannot occur in a transparent, passive medium where electromagnetic radiation is being absorbed at all frequencies, as pointed out by Landau and Lifshitz. Here we show, using

Light speed reduction to 17 metres per second in an ultracold atomic gas

Techniques that use quantum interference effects are being actively investigated to manipulate the optical properties of quantum systems. One such example is electromagnetically induced transparency,

Focusing of beams into subwavelength area in an inhomogeneous medium.

Propagation and focusing of nonparaxial Gaussian beams with spherical wavefront in a graded-index medium are investigated using quantum-theoretical method of coherent states. Explicit expressions for

Observation of subluminal twisted light in vacuum

Einstein's theory of relativity establishes the speed of light in vacuum, c, as a fundamental constant. However, the speed of light pulses can be altered significantly in dispersive materials. While