At what scale does time dilation manifest itself? Is time dilation dictated only by the velocity of entire large objects (people, watches)? Or is it based upon its component particles? For example if a clock is at rest with respect to a room, but its component atoms are vibrating at a speed of 1 km/s, is the latter speed used? Or is a much smaller scale used (objects vibrating on the Planck scale, etc.)? I would also like to know, just out of curiosity, what kinds of speeds are seen at the atomic or subatomic level. There is obviously very little net displacement, but I am wondering about the speeds at which objects "vibrate."