# 2D space-time curvature [closed]

Actually, why is the space-time curvature considered 2D plane. As 2-D dimensional space-time curve is used to explain why moon revolves around the earth stating because the massive objects wraps the space-time curvature i.e bends it due to which low massive objects like moon revolves around the large massive objects like earth. So, here the space-time curve is considered 2 Dimensional. Is it really or am I missing some points over here. And I m newbie Relativity topic.

## closed as unclear what you're asking by ACuriousMind♦, Gert, user36790, Daniel Griscom, MartinJan 7 '16 at 12:45

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• – Qmechanic Aug 17 '15 at 9:34
• Space-time curvature is not "considered 2D plane". – ACuriousMind Aug 17 '15 at 13:57

## 1 Answer

It is an analogy, as a 4 dimensional equivalent would be hard to draw, and if it was 3 dimensional, you couldn't see what's inside!

• For the case of flat spacetime, attempting to draw the 3D+T spacetime in its full glory will give you a bunch of 4 dimensional analogues of hyperbloids. There is too much clutter in that 2D projection of it (because you drew it on a piece of paper) or even a 3D model, and you cannot work with that reliably – Secret Aug 17 '15 at 8:54
• Now, here is my actual question... why do we have to always assume space-time curvature plane with solar plane. Can't we consider being perpendicular to solar plane. This way if we assume we can have a 3D curvature and as it bends the curve as in 2D, it similarly bends the curves around it in every possible ways. I mean for example, Earth would be touching every curves i.e. top bottom sides and their should be bending of curves (as massive objects bends the curve). Now, how does the moon(low massive objects) revolve around earth. Continue to next comment. – Sagaryal Aug 17 '15 at 12:47
• As it seemed in 2D, the bending kind of created a slope in space-time curve like their is a gravitational force acting from below and was assumed moved towards earth.There should be such in other directions too. How do we explain this on the kind of analogy I assumed. – Sagaryal Aug 17 '15 at 13:11
• @Sagaryal You can't explain it using that analogy. That's why it's an analogy: it's necessarily incomplete. In fact, the rubber sheet analogy isn't even close to a useful model. It's only meant to illustrate that space gets warped near massive objects. It is not meant to give a correct model of General Relativity. – Kyle Aug 17 '15 at 13:21