As the tittle says, I am constantly hearing about spacetime, which I sort of get (it’s a 4D space, with 3 spatial and 1 temporal axis) and curvature, which I do not get. What is curved in spacetime? When we say geodesics, what are they representing? I am getting the feeling that it is something like the spatiotemporal distance between two events that is being modified, but what does it mean in physical terms? Is it even physical, since two observers can disagree in almost everything, except the order of casually linked events?
Or I am thinking it too much, and it’s only a model of interpreting observation that only approximates complex reality up to a point?
In: 5
In ELI5 terms, a sheet of paper is flat, a globe is closed, and a frying pan is open. If you can conceive of those notions in 3+1 dimensions, you understand spacetime curvature
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