Traveling at relativistic speeds, close to the speed of light, has several significant effects due to the theory of special relativity. Here are some of the key effects:
Time Dilation: According to the theory of relativity, time appears to pass slower for objects moving at relativistic speeds relative to an observer at rest. This means that time would seem to move more slowly for a fast-moving object compared to a stationary observer. As the speed approaches the speed of light, the time dilation effect becomes more pronounced. Therefore, from the perspective of an observer, an object moving at relativistic speeds would experience time at a slower rate.
Length Contraction: Another consequence of special relativity is length contraction. When an object moves at relativistic speeds, its length appears to contract along the direction of motion as observed by a stationary observer. This means that the object would appear shorter in the direction of motion compared to its rest length. As the velocity approaches the speed of light, the length contraction effect becomes more significant.
Mass Increase: According to special relativity, the mass of an object increases as it approaches the speed of light. This effect is known as relativistic mass increase. As the velocity of an object increases, its mass also increases, making it more difficult to accelerate further. This phenomenon is commonly expressed by the equation E = mc^2, where E is the energy, m is the mass, and c is the speed of light. As an object's speed approaches the speed of light, its mass approaches infinity.
Energy Increase: As an object's mass increases at relativistic speeds, its kinetic energy also increases. The relationship between energy and velocity in special relativity is given by the equation E = (γ - 1)mc^2, where γ is the Lorentz factor (γ = 1/√(1 - v^2/c^2)) and v is the velocity. At relativistic speeds, the kinetic energy of an object becomes significantly larger compared to its rest energy.
Regarding your question about whether an object moving at relativistic speeds would look like the same object, the effects mentioned above would certainly alter how the object is observed. The time dilation, length contraction, and mass increase would result in significant changes in how the object appears to an observer. For example, its shape may appear distorted due to length contraction, and its color might change due to the relativistic Doppler effect. However, it's important to note that these effects would be perceived by an external observer relative to their own frame of reference. The object itself would not experience any change in its own perception of itself.