can inertial reference frame ever have "lenght contractions" in 3d or in rest? hi! thank you for all answers in this topic in previous threatin same topic. i open this new thread in same topic but here i try to keep the issue here very short and readable , with no speculation and concentrating to the question. the question is about length contractions: relativistic inertial reference frame in special relativity can have relative properties like slower time and lorenz contraction. also particle in that reference frame has more relative momentum and more relative energy than particle at rest. these properties are always connected to the relative velocity of the reference frame in special relativity, and once the frame or particle decelerate to relative rest, these properties disappears and the particle becomes "normal". but can such inertial reference frame or a object ever exist even in theory that has length contraction in all 3 space dimensions at the same time? secondly can inertial reference frame have lenghth contractions when it is in rest can there be length expansions? i know a bit about relativity theories but i havent ever heard anyone talking about such things.