lightyears are not a part of childish sci-fi stories,my dear friend.it's just a measure of distance/length.in more scientific terms,a light-year is a unit of length, equal to just under 10 trillion (i.e. 1013) kilometers. As defined by the International Astronomical Union (IAU), a light-year is the distance that light travels in a vacuum in one Julian year

Going to church no more makes you a Christian than standing in a garage makes you a car. ~ Garrison Keillor