Ive heard that length contraction does not occur when the movement of the object is perpendicular to the observer. Is this correct? Say two identical rings were travelling at eachother at relativistic speeds, whilst the observer is perpendicular to them. Ring A would see ring B contract and therefore pass through whereas ring B would see ring A contract and go through it. Since both cant contract AND pass through eachother as seen by the perpendicular observer, it does not apply to perpendicular frames of reference.