According to Einstein's theory of relativity, specifically the theory of special relativity, traveling at speeds close to the speed of light does not violate the theory itself. However, it leads to some counterintuitive and fascinating consequences.
One of the main implications of special relativity is that the speed of light in a vacuum is constant and the same for all observers, regardless of their relative motion. This means that no matter how fast an observer is moving, they will always measure the speed of light to be approximately 299,792,458 meters per second (or about 186,282 miles per second).
As an object approaches the speed of light, several phenomena occur:
Time dilation: According to special relativity, time appears to slow down for an object in motion relative to a stationary observer. As an object's velocity increases, time dilation becomes more pronounced. From the perspective of a stationary observer, it would seem as if time is passing more slowly for the fast-moving object. This phenomenon has been experimentally verified, such as in the famous example of muons created in Earth's atmosphere that reach the surface despite their short half-life.
Length contraction: Length contraction, also known as Lorentz contraction, refers to the phenomenon where an object's length appears to shorten along its direction of motion relative to a stationary observer. As an object's velocity increases, its length in the direction of motion becomes shorter when measured by a stationary observer. This effect becomes more significant as the object approaches the speed of light.
Relativistic mass increase: According to special relativity, as an object's velocity increases, its mass appears to increase. This phenomenon is often referred to as mass dilation or relativistic mass increase. The faster an object moves, the greater its apparent mass becomes. However, it's important to note that the object's rest mass, which is its mass at rest, remains constant. The increase in mass is a result of the object's energy increasing with its velocity.
These effects become more significant as an object approaches the speed of light. In theory, to reach the speed of light, an object would require infinite energy, which is why it is impossible for massive objects with rest mass to attain or exceed the speed of light. This restriction is known as the light-speed barrier or light-speed limit.
So, while traveling at speeds close to the speed of light doesn't violate Einstein's theory of relativity, it does lead to extraordinary consequences, such as time dilation, length contraction, and relativistic mass increase, which challenge our everyday intuitions about space and time.