The speed of light in vacuum, commonly denoted c, is a universal physical constant important in many areas of physics. Its exact value is defined as 299792458 meters per second (approximately 300000 km/s, or 186000 mi/s).It is exact because, by international agreement, a meter is defined as the length of the path travelled by light in vacuum during a time interval of 1⁄299792458 second. According to special relativity, c is the upper limit for the speed at which conventional matter, energy or any signal carrying information can travel through space.
Nothing can travel faster than light. But what if we switched the rules a little?
Imagine a world where the speed of light was slower. Way slower. About the speed that sound travels at. In turn, the sound in that hypothetical world would be accelerated until it reached the speed of light.