Quote by Bjarne
So long that time multiplied with speed, is a valid equation, both observer cannot agree about the circumstance of the same orbit.
Right?
So you can sit on the Earth and calculate the orbit of the Earth and you will get a certain result. – You will believe this is 100 % true.
A ISS inhabitant can do the same from his perspective,  and from the exact same orbit, he also will believe his result is absolute right about the circumstance just calculated.
But since time is not the same, (and I assume we agree speed is the same) – we have now 2 different circumstances,  these can’t be the same.
So who is wrong and who is right?
I mean do you believe the orbit of the Earth can be both 250 billion km and also 500 billion km ?
It doesn’t sound logical  and hence hard to buy.

There is a race track near my town. One driver, racing for team ISS, stays always on the outside edge of the race track, and the other, racing for team Earth, stays always on the inside edge of the race track.
Using their odometers they each measure the length of 100 billion laps around the
same track. One obtains a length of 250 billion km and the other 500 billion km.
So who is wrong and who is right? I mean, do you believe that the track can be both 250 billion km and also 500 billion km? It doesn't sound logical  and hence hard to buy.
Therefore, the laws of physics must clearly be different on the inside of the track and the outside.