The speed of light, denoted by the letter "c," is considered the maximum theoretical speed in our universe according to the theory of special relativity, formulated by Albert Einstein in 1905. There are several reasons why the speed of light is regarded as the ultimate speed limit:
Consistency with Observations: Over the years, numerous experiments and observations have consistently shown that the speed of light is constant in a vacuum, regardless of the motion of the source or the observer. This consistency led Einstein to propose that the speed of light is a fundamental and unchanging constant in the fabric of our universe.
Lorentz Invariance: Special relativity is based on the principle of Lorentz invariance, which states that the laws of physics remain the same for all observers moving at constant speeds relative to one another. By setting the speed of light as a universal constant, special relativity maintains the consistency of physical laws across all inertial reference frames.
Time Dilation and Length Contraction: According to special relativity, as an object approaches the speed of light, time dilation occurs, and its length contracts in the direction of motion. As an object with mass gets closer to the speed of light, its mass would approach infinity, requiring an infinite amount of energy to reach or exceed the speed of light. This phenomenon prevents anything with mass from ever attaining or surpassing the speed of light.
Causality and Paradoxes: Allowing objects with mass to travel faster than light could lead to causality violations and paradoxes. For instance, an object moving faster than light could arrive at a destination before a cause (such as a signal) has been sent. This could lead to situations where cause and effect become reversed, undermining the fundamental principles of causality.
While there are theoretical particles like neutrinos that have been observed to move at speeds very close to the speed of light, they still do not exceed it. As of our current understanding of physics, the speed of light stands as the ultimate cosmic speed limit, and nothing with mass can travel faster than it in our universe.