Can an entity have properties of its own, known only to itself, were it capable of knowing, and so absolute not relative? Isn't the falling item, whether observed from a train or from an embankment, only what it is itself, and not the varying impressions that observers receive?
We only know what we can observe ("seeing is believing") but that is a problem not an advantage. Otherwise why say "only"? Our impressions are always to some extent out-of-step with underlying reality.
The inner properties of something may be held in a fixed frame of reference which is the containing item itself. Equally the frame of reference that is authoritative for effects on an entity, is its own frame of reference, what it encounters from its vantage point. That we cannot see things that way is merely our problem.
Two entities may collide and the fact that various others cannot see the collision at the same times is their problem. It's no consolation to the items which collide and are destroyed. When did it happen? When the entities collided. Never mind where we were. We had a distorted view of each entity, and we will receive a distorted view of when they collided, but the entities are not in any doubt themselves. When did it happen? Ask the collision. When did we see it? At different times.
Things have conditions and properties which we try and ultimately are not able precisely to discover. Does the theory of relativity confuse what is observed with what is at the point that owns the attribute, where the attribute is a condition of the entity and not a condition of its image? Images are distorted, but attributes that underly them are authoritative. Relying on images, we cannot see in a precise or timely way, that which the items in question "experience" or bear as attributes of themselves.
So turning to that intangible and much denied concept, the soul, and thereby losing the goodwill of any readers who've got this far, maybe it is the sum of one's absolute attributes, known not to oneself even but to itself, invisible and inexpressible except imperfectly, about which one can only wonder.