>>14297270You would have to ensure that the measuring devices themselves are static to begin with. You'd have to kick them out of any gravity well including the local galaxy's too.
If you don't do that and allow the devices to float around with the gravitational pull that both of you share, then the reference becomes you yourself measuring yourself - it's as redundant as just doing it literally.
And here's where the circular redundancy appears. To freeze these measuring devices in place, you'd need to know what the frozen frame of reference is, which would be the answer to your question to begin with. In other words if you could craft such a device then you already know the measurements that it is about to measure, but you need these measurements to measure them.
So what's this? It's a Münchhausen trilemma. You cannot do anything about it without making an unproven axiomatic assumption. You can probably refine it into an actual physical law if you care so much, that discovering the objective frame of reference is physically impossible in this universe. Perhaps there's such that I'm not aware of. If there isn't, then I hereby name it
>anon's midwit proof of relativity 
