The speed of light in a vacuum, denoted by the symbol 'c,' is considered a fundamental constant of nature. In the theory of relativity, formulated by Albert Einstein, the speed of light plays a crucial role.
According to the theory of relativity, the speed of light is achievable and constant for all observers in all inertial reference frames. It is the maximum speed at which information, energy, or any physical interaction can propagate through space.
In practical terms, light is an electromagnetic wave, and its speed is determined by the properties of electromagnetic fields and the permeability and permittivity of free space. These properties give rise to the speed of light being approximately 299,792,458 meters per second (or about 186,282 miles per second).
Achieving the speed of light requires the absence of mass or a form of energy that has no mass. Photons, which are massless particles and carriers of electromagnetic radiation, travel at the speed of light in a vacuum. They do not experience the same constraints as objects with mass and can achieve the speed of light.
It's worth noting that objects with mass, such as particles with rest mass, require an infinite amount of energy to accelerate them to the speed of light. This is due to the increase in their relativistic mass as they approach the speed of light, as described by Einstein's theory of relativity.
Therefore, while the speed of light is achievable for massless particles like photons, it is unattainable for objects with rest mass, as they would require infinite energy to reach or exceed the speed of light.