What is the speed of light in a vacuum?

The speed of light in a vacuum is universally recognized to be approximately 3.0 x 10^8 meters per second. This value is a fundamental constant in physics, often denoted by the symbol 'c'. The speed of light is crucial not only in the study of optics but also in the realms of physics and cosmology, where it plays a key role in theories such as relativity.

This specific speed signifies how fast light travels through the empty space of a vacuum, which is the fastest speed at which information or matter can be transmitted according to our current understanding of the laws of physics. Understanding this speed is essential for various calculations in optics, such as determining how light interacts with different media, calculating distances in astronomy, and understanding phenomena like refraction and diffraction.

The other options represent either incorrect values or speeds that are much slower than the speed of light in a vacuum, which is why they do not hold true in this context.