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## Main Question or Discussion Point

I was thinking - and reading a bit - about the size limit on accelerated frames, and there is an interesting and relevant result I found.

If we rephrase the question from "is there a size limit on an accelerated frame" to "is there a size limit on an accelerated body in irrottational born rigid motion", it is known that the answer is yes, there is a limit. This was pointed out by Born in 1909, according to wiki;

https://en.wikipedia.org/w/index.php?title=Born_rigidity&oldid=961398833

So, as long as we demand that our accelerated frame have the property that objects "at rest in the frame" maintain a constant distance from each other, then there IS a known limit on the size of an accelerated frame.

If we rephrase the question from "is there a size limit on an accelerated frame" to "is there a size limit on an accelerated body in irrottational born rigid motion", it is known that the answer is yes, there is a limit. This was pointed out by Born in 1909, according to wiki;

https://en.wikipedia.org/w/index.php?title=Born_rigidity&oldid=961398833

The limit is that the proper acceleration must be less than c^2/R, where R is the radius of a sphere in which the body is located. I couldn't tell from the wiki article where the proper acceleration was measured, presumably at the center of the sphere - it will vary.wiki said:Already Born (1909) pointed out that a rigid body in translational motion has a maximal spatial extension depending on its acceleration, given by the relation ....

So, as long as we demand that our accelerated frame have the property that objects "at rest in the frame" maintain a constant distance from each other, then there IS a known limit on the size of an accelerated frame.