Length contraction is a concept in special relativity that describes how an object's length appears to decrease when it is moving at high speeds relative to an observer.
Lorentz and Einstein both proposed theories of length contraction, but they differ in their explanations of why it occurs. Lorentz's theory states that objects physically contract in the direction of motion, while Einstein's theory states that it is the perception of length that changes due to the effects of time dilation.
Length contraction causes an object's length to appear shorter when it is moving at high speeds relative to an observer. This means that the measured length of the object will be shorter than its actual length.
Length contraction is a real phenomenon that has been confirmed through numerous experiments and observations. While it may seem like a perception, it can be mathematically calculated and has practical implications for things like particle accelerators and GPS systems.
Length contraction is typically only observable at extremely high speeds, close to the speed of light. However, it can also be observed in everyday life through the decay of muons in Earth's atmosphere, which travel at high speeds and experience length contraction as a result.