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This question appeared to me when I was thinking about General Relativity. During the expansion of space, the space in which particles reside is expanded. Now, general relativity states gravity is the curvature of space-time. So does this expanded fabric of space-time behave the same way as regular space-time (as in space-time before some magnitude of expansion), or does it behave in a different way than how our normal Earth tensile materials which have are stretched?

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    $\begingroup$ Welcome to the Astronomy SE! It seems you have multiple questions you're considering here; perhaps you could narrow it down to one and put the others as separate questions? $\endgroup$
    – Justin T
    Feb 15, 2023 at 19:13

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The only physical property of a point in spacetime is its curvature (specified by a many-component tensor). There is no property that tells us "how much it has expanded". So "expanded" space behaves identically to "unexpanded" space.

Of course, it could not be any other way, because the "expansion of space" is just a mathematical convention and not (locally) a physically real phenomenon (see my answer to "How do we know we're not getting bigger?"). Space isn't stretching in the first place.

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