On the Wikipedia page for the Twin Paradox, the example lays out the perspective of each twin in turn. Both twins are portrayed as understanding the ship's velocity as v, and the travelling twin's sense of time is then explained by saying that the earth-distant star system, being in effect one giant object, undergoes length contraction ie the twin travels less distance, ie less time went by for the twin. But if the entire rest of the twin's system, ie. the twin's whole sense of distance, has shrunk, shouldn't the twin's sense of velocity shrink too? How can they agree on velocity but not distance, when v = d/t ? The v is relative to what?
Or are we saying that our usual sense of reality is wrong, when we think of an object's location at a given time (absolute or otherwise) as an intrinsic truth upon which we define velocity as Δlocation/unit time, when in fact it's the other way around and an object's velocity is intrinsic. Are we saying velocity actually IS absolute even though time and distance aren't?