Take the 2-minute tour ×
Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. It's 100% free, no registration required.

when the sound barrier is broken,a series of concentric waves of sound is produced.Does it mean when the speed of light barrier is broken,a ripple of photons are created in the space-time fabric?

share|improve this question
add comment

2 Answers 2

The light barrier cannot be broken in vacuum as you should know by now. c is the velocity of light in vacuum.

But, within a medium light can have a lower phase velocity in the medium, depending on the index of refraction of the medium. There the barrier phenomenon can appear and it is called Cherenkov radiation.

While electrodynamics holds that the speed of light in a vacuum is a universal constant (c), the speed at which light propagates in a material may be significantly less than c. For example, the speed of the propagation of light in water is only 0.75c. Matter can be accelerated beyond this speed (although still to less than c) during nuclear reactions and in particle accelerators. Cherenkov radiation results when a charged particle, most commonly an electron, travels through a dielectric (electrically polarizable) medium with a speed greater than that at which light would otherwise propagate in the same medium.

This phenomenon has practical applications as in particle detectors etc.

share|improve this answer
add comment

Speed of light in the vacuum cannot be exceeded by matter, so the barrier cannot be broken.

Speed of light in medium, however, may be surpassed by a charged particle also moving in that medium, resulting in Cherenkov radiation. But it is hardly something as "ripple in the space-time fabric".

share|improve this answer
add comment

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.