Is Spacetime a Field in General Relativity?

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Could spacetime itself be a field?
 
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No, according to the current understanding acquired since the beginning of the 20th physics, spacetime is a mathematical model/environment where all physics takes place, in particular where particles and field 'live'.
 
Yes, in General Relativity, spacetime is a field described by a metric tensor.
 
I think that in GR I would associate spacetime with the whole Riemannian manifold, not just the metric.
 
No, it is a quality of the gravitational field but is not a field in it's own sense.
 
O10infinity said:
Yes, in General Relativity, spacetime is a field described by a metric tensor.
Spacetime is not a field. A spacetime is a pair (M,g) where M is a smooth manifold and g (the metric) is a tensor field on M. It's considered OK to refer to M as "spacetime", even though it would be more accurate to call it something like "spacetime's underlying manifold". If we use this terminology, we can say that the metric is a field on spacetime.
 

Thread 'Euclidean geometry and gravity'

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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Thread 'Is the variation of the metric ##\delta g_{\mu\nu}## a tensor?'

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...
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