[yor_on]

Because that will be what you expect, that those laws rules and properties will change.

[yor_on]

and it comes back to the question of what 'dimensions' are. a construct or a 'origin', and that goes for all four of them. Length, width, height, time.  But we should exchange time for 'clocks' if we want it to be a construct, as I think. With 'time' becoming one of the 'laws' able to create a universe.

[yor_on]

The universe you consist of has a time, defined by your local clock. Me joining your frame of reference will share the same clock.

[yor_on]

We doing the same measurement, although under different relative motions, inside a black box, should be able to reach a agreement on them. Locally defined you and me share the same 'frame of reference' according to our experiments.

[yor_on]

Our clocks will, according to a distant observer, differ due to our relative motion being different from each other.

[yor_on]

Worth thinking of, isn't it?

[yor_on]

It doesn't really matter if we set the distant observer as being the origin from where set our different speeds, or not. The principle will be the same for him anyway, that he finds our clocks to differ relative his. None ticking the same.

[yor_on]

The mass of the black box?

Well, lets assume those two black boxes are 'identical' in all terms for it.
Except the relative motions.

[yor_on]

" Using my definitions it becomes a presumption to assume that you can set a clock to the very small even though you can define probabilities for it. What guarantees that your local macroscopic clock is what defines it? "

Locality, and relative motions. That's how we define repeatable experiments on earth.

[yor_on]

We also go out from an assumption that this will hold wherever you are. And we are 'testing it' repeatably due to earths and the solar system, and our galaxies relative 'motions'. And they are as real as can be, everything moves in this universe as far as I know.

[yor_on]

So motion exist, but what is it? If you're going to say displacements then you didn't get what I mean.

[yor_on]

For those thinking that a acceleration is what sets a time dilation it will though. They will want a same origin and different accelerations from it to reach those speeds.

[yor_on]

But then you have the black boxes, and their 'identical frames of reference' locally defined.

[yor_on]

We can do another experiment, two identical origins at different uniform motions. Two rockets, identical, leaving each one, accelerating at a identical pace, still finding each other having different clocks once being in a relative motion. 

No clock will be found to be the same here either. But the experiments will. This one contains of stipulations that needs to be fulfilled, stopping their acceleration at a same 'gravity' etc. but the point is that there is no way to define those origins relative speed, locally. So no matter your origin you start from a same local definition. Speeds doesn't matter for it locally.

[yor_on]

If it did you could assume that accelerating in the motion of what you define earth to have you would reach a higher speed than if you accelerated at a same pace against that 'motion'. You're welcome to prove this to be true, if you can.

[yor_on]

If you could it would mean that relativity is wrong. It would mean you finding a definition of absolute speeds, no longer relative. It's all about black boxes, not about using earth as your reference frame.

[yor_on]

It should also mean that you would have to expend more energy pushing yourself away, accelerating in the 'motion of earth', than you would have to accelerating against this motion, if I'm thinking right here.

[yor_on]

I haven't checked it up but I think that both Newton and Einstein would agree on this not being true. That relative motion would matter for the energy expended as you accelerate from it. If you define what you leave as your reference frame it will matter, but if you don't, staying in that black box it has no meaning what speed you define to your origin. That it matters in a collision is another thing depending on your relative speeds versus each other, and there it can be as complicated as you want it to be depending on the frames used for defining it.

[yor_on]

If you're starting to feel a slight headache by now I can assure you you're not alone.

[yor_on]

What I mean about 'the frames' defining your collision. You can take two cars colliding, each one traveling towards each other at 50 km. You find a energy from those facts involved together with the mass. But let's assume one of the cars are moving against the motion of earth as defined relative some other galaxy, the other with it. It doesn't matter, does it?