I Is there only one structure of the universe?

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(See illustration) Object A is moving, to the right, really fast towards object B on the x axis. At (0,0) they meet. There are two rocks next to each other ahead of the speeding object A. The two rocks are shown as world lines red and green as they would exist for each observer. Assume that the length contraction is 1/2 for object A.

There would seem to be two different structures of the same thing in the universe. Is this correct?
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student34 said:
There would seem to be two different structures of the same thing in the universe. Is this correct?
No. You've asked the same question in multiple previous threads, and the answer hasn't changed.

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From $$0 = \delta(g^{\alpha\mu}g_{\mu\nu}) = g^{\alpha\mu} \delta g_{\mu\nu} + g_{\mu\nu} \delta g^{\alpha\mu}$$ we have $$g^{\alpha\mu} \delta g_{\mu\nu} = -g_{\mu\nu} \delta g^{\alpha\mu} \,\, . $$ Multiply both sides by ##g_{\alpha\beta}## to get $$\delta g_{\beta\nu} = -g_{\alpha\beta} g_{\mu\nu} \delta g^{\alpha\mu} \qquad(*)$$ (This is Dirac's eq. (26.9) in "GTR".) On the other hand, the variation ##\delta g^{\alpha\mu} = \bar{g}^{\alpha\mu} - g^{\alpha\mu}## should be a tensor...
I asked a question here, probably over 15 years ago on entanglement and I appreciated the thoughtful answers I received back then. The intervening years haven't made me any more knowledgeable in physics, so forgive my naïveté ! If a have a piece of paper in an area of high gravity, lets say near a black hole, and I draw a triangle on this paper and 'measure' the angles of the triangle, will they add to 180 degrees? How about if I'm looking at this paper outside of the (reasonable)...

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