The speed of light in the vacuum is defined as a universal constant of value 299 792 458 m / s (it is usually rounded to 300 thousand kilometers per second). It is designated by the symbol c (from the Latin celéritās, meaning celeridad or fastness).
In non-empty spaces the speed of light is less affected by the electromagnetic characteristics of the medium and the refractive index. This velocity is not only light but the speed of propagation in the vacuum of all electromagnetic radiation.
The speed of light was established by Albert Eintein in Theory of Special Relativity, published in 1905. Einstein came to call the speed of light as "the limiting speed of the Universe", the speed that nothing can overcome. In September 2011 we published the results of an experiment in which neutrinos were observed moving at a rate higher than the constant c questioning the theories of Albert Einstein.
However, later experiments refuted these data and the scientists reviewed the experiment to discover that there were errors in some measurements. The speed of light remains the maximum theoretical speed attainable by any object in the Universe.
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Source: Exploring the universe
Credits: Minute physics