"Space is a vacuum, it doesn't have points?"How do you measure that if you don't know its destination?
Distance is a measurement between two different points in space. You're asking how to measure the distance between one point.
Space is a vacuum; it doesn't have "points." It is full of THINGS, though--planets, moons, stars--which are in motion relative to each other but, for the most part, can be used as a measurement of distance and speed, but in deep space, this just isn't possible.
This is why I asked the question. In aircraft, you can determine your speed one of two ways: measuring the speed of the air that's rushing past you, or measuring your speed relative to fixed points along the GROUND. Since space has no air, and since there is no ground on which to determine fixed points, an "Absolute speed" is therefore meaningless: there are no fixed points IN space for you to measure against.
All a "point" is, is a definition of location by the use of coordinates. OF COURSE VACUUMS HAVE "POINTS IN THEM." If you can say "in this box, with absolutely no atmosphere inside it, you need to observe a location 3 meters from the floor, 4 meters from the nearest wall, and 5 meters from the wall to your left..." then you've just proven, incontrovertibly, that "there are points in a vacuum." A "point" is not a measure of mass, it's a measure of position (and can include other "dimensions" besides X, Y, and Z... such as "t" for "time")
Here's the thing... and this is really the area of dispute... we do not know if there is any such thing as an "absolute coordinate system" or if there is only a "relative to the fabric of the universe" coordinate system (with that fabric itself twisting and flexing in ways we cannot envision... but which are often referred to as the basis of the "Chi factor" in some fudged warp-drive calculations).
I find it impossible to believe that "all frames of reference are purely relative." For the simple reason that the very math behind the statement can, itself, be used to prove that statement false (though the proofs then raise howls of outrage from certain quarters). Our "math model" is, at best, very rough and incomplete. Can we at least acknowledge THAT?
If you assume that "all motion is relative," and you believe in "time dilation" as it's described within this same math-model... well, "time dilation" cannot exist. Because "time dilation" states that time passes... LITERALLY... at different rates depending on how fast one object is moving relative to another object.
But... if all motion is relative... how do you determine which object is really moving, and which is really stationary? Which one slows down, and which one doesn't?
The math works... IF you assume that all frames of reference must be evaluated with respect to some (up til now undiscovered) "universal frame of reference." Otherwise... it fails, utterly. Any problem which can give multiple contradictory answers is clearly not being solved properly.

So... I believe that there IS some "ultimate frame of reference," and I believe furthermore that eventually... once we start exploring the universe beyond our little pond here... we will gain enough experimental data to determine its nature. So far, we're tadpoles in a pool of stagnant water, pretending we understand the ocean depths, because we know a little bit about our particular puddle of mud.
