The speed of light in a vacuum, denoted by the symbol "c," is approximately 299,792,458 meters per second or about 186,282 miles per second. It is considered to be the ultimate speed limit in the universe according to our current understanding of physics.
In the theory of special relativity, formulated by Albert Einstein, it is postulated that the speed of light in a vacuum is constant for all observers, regardless of their relative motion. This means that light always travels at the same speed, regardless of the motion of its source or the observer.
As an object with mass accelerates towards the speed of light, several effects come into play. First, the object's mass appears to increase according to the concept of relativistic mass. This means that it requires more and more energy to accelerate the object further, and it would require an infinite amount of energy to reach the speed of light. This increase in mass is a consequence of the energy-mass equivalence principle described by Einstein's famous equation E=mc².
Additionally, as an object approaches the speed of light, time dilation occurs. Time dilation means that time appears to slow down for the moving object relative to an observer in a relatively stationary frame. This effect becomes more pronounced as the object's speed approaches the speed of light.
According to the theory of special relativity, an object with mass cannot reach or exceed the speed of light in a vacuum. If such an object were to somehow reach the speed of light, its mass would become infinite, and the amount of energy required to accelerate it further would also become infinite. This is why it is considered impossible for an object with mass to reach or exceed the speed of light.
However, it's important to note that the restriction on objects with mass does not apply to massless particles like photons, which travel at the speed of light. Photons have no rest mass and are always moving at c when measured in a vacuum.