No, length contraction in special relativity does not imply a decrease in the mass of an object as it moves at relativistic velocities. Length contraction is a phenomenon described by special relativity, which states that an object moving at a significant fraction of the speed of light will appear contracted or shortened along its direction of motion when observed from a relatively stationary reference frame.
According to special relativity, as an object's velocity approaches the speed of light, its length in the direction of motion shrinks relative to its length at rest. This effect is observed from the perspective of an observer in a different reference frame than the moving object. However, it's important to note that the contraction of length is only apparent from the perspective of the observer in the other frame, and the object itself does not physically change in size.
The mass of an object, on the other hand, is not directly related to length contraction. In special relativity, the mass of an object is considered to be invariant, meaning it does not change with velocity. The mass of an object remains constant regardless of its motion relative to different observers. This concept is known as the "mass-energy equivalence," expressed by the famous equation E=mc², where E represents energy, m represents mass, and c represents the speed of light.
It's worth noting that relativistic effects, such as length contraction and time dilation, are often interconnected. As an object approaches the speed of light, both length contraction and time dilation occur simultaneously. The object appears contracted in length, and time appears to pass more slowly for the moving object relative to observers in a different reference frame. However, these effects do not imply a change in mass.