The slowest moving object in the universe is a difficult concept to define precisely. In the context of motion, it is important to consider the frame of reference from which we are observing. In the absence of external forces, an object at rest in one frame of reference might appear to be moving in another frame of reference.
However, if we consider the cosmic microwave background (CMB) radiation, which permeates the universe, it can be viewed as a reference frame that is at rest with respect to the overall expansion of the universe. From the perspective of the CMB frame, we can say that all objects in the universe, including ourselves, are in motion. In this sense, the slowest moving objects would be the ones that have the least relative motion compared to the overall expansion of the universe.
As for the concept of time dilation and relativity, according to the theory of general relativity, time can be experienced differently depending on the strength of gravity and relative motion between observers. This means that two observers in different gravitational fields or moving at different velocities can experience the passage of time at different rates.
To provide a specific age difference in terms of relativity, we would need to specify a particular scenario. For example, if one observer is in a strong gravitational field while the other is in a weak gravitational field, the observer in the weaker field would experience time passing slightly faster. Similarly, if one observer is moving at a significant fraction of the speed of light relative to another observer, time dilation effects would occur.
However, for everyday life on Earth and within our solar system, the effects of time dilation are extremely small and negligible. The age difference between observers due to relativity would generally be on the order of microseconds or less. It is only in extreme conditions, such as near black holes or at speeds close to the speed of light, where significant time dilation effects become noticeable.