Consequences of Special Relativity

The relativity of simultaneity is the concept that simultaneity is not absolute, but depends on the observer's reference frame.

Time dilation is an actual difference of elapsed time between two events as measured by observers moving relative to each other.

The twin paradox is a thought experiment: one twin makes a journey into space and returns home to find that twin remained aged more.

Objects that are moving undergo a length contraction along the dimension of motion; this effect is only significant at relativistic speeds.