That’s the relative bit. It literally doesn’t matter, there is no way to know whether you (and the earth) are stationary and the second clock is blasting off away from you at a bazillion miles an hour, or both you and the second clock started going a bazillion miles an hour* and the clock launched off in such a way as it was stationary. The resulting time dilation is the same.
assuming for the sake of argument that the earth is moving in a straight line at a bazillion miles an hour, it’s not of course but to consider that you need to think about gravity and acceleration. That’s where things get interesting.
I think the meaning of my OP wasn’t clear. I understand about relative frames of reference. But I’m the experiment I referenced in the OP, two clocks were separated and brought back together. Outside frames of regency shouldn’t come into play.
I think Whack-a-Mole understands the gist of it:
Einstein was famous for his gedankenexperiments - accelerating elevators and blind beetles - so let me propose one. You are standing on the sun with 3 clocks all set to the same time. You reach out with your very long arms and set one on Mercury and one one Pluto simultaneously and let them go along their way.
After a year, you reach out and pluck them off of their respective planets, put all three together again and check their times against your control clock. If Whack’s speeds are right, the Pluto clock will be slower and Mercury’s slower still, right?
So their individual speeds do matter in a real way to the clocks - not just a frame of reference way.
Ok, now, suppose you have 3 clocks all set to the same time. From your spot on the sun, you reach out and place one on the earth and one one a rocket sitting on earth. The earth is traveling at 66,000 mph in its orbit around you. As soon as you place the clock on the rocket, it blasts off the earth with 66,000 mph’s worth of thrust in the opposite direction of earths orbit. Essentially causing it to become stationary from your sun frame of reference. 365 days later, the earth catches up to it bringing those 2 clocks together. You reach out and bring them to the sun and compare their times. What will be relative times of the clocks? Will the rocket clock’s time be slower or faster than the earth clock?
There’s no way to instantly place clocks on the earth. Placing clocks on earth means they travel there (presumably at or below the speed of light).
From your post on the sun, neither of those clocks are sync’ed with your sun-clock and aren’t ‘stationary’ to your clock
It still seems to be an issue of understanding what reference frames are and that there is no preferred frame, i.e. simultaneity in the sense you mean doesn’t exist.
This gets you to the core of the twin paradox and its ilk. What do you mean by “pluck them off”? That generally means they swap reference frames. Every every change of reference frame matters.
And what is meant by “simultaneously”. Simultaneity is another stumbling block in thought experiments. If you are standing on Mercury versus standing on Pluto, the apparent order of events is not so well defined.
Well, no, not really. At any given point you can define a reference frame based on the CMB, but it’s going to be a different reference frame at each point. And even if you define your reference point, it’s still no more privileged reference frame than any other, with respect to Special Relativity.
And for objects in orbit, you can’t do the calculations with just Special Relativity. General Relativistic effects are also relevant, larger than the SR effects, and in the opposite direction.
Yeah. I wasn’t getting my thoughts straight.
Would the CMB be flat inside a galaxy or galaxy cluster? Given the gravitational attraction holds them together I assume space remains constant?
Still only another undistinguished frame, but an odd thought. I guess frame dragging has an effect as well, albeit very tiny.