Quote:
Originally Posted by sjastro
No one knows how a mass curves space time because General Relativity is only a semi phenomenological theory where the emphasis is to explain the effect rather than the cause. It explains the concept of the Newtonian potential of gravity as a distortion of space time without explaining how space time curves. Newtonian gravity is purely a phenomenological theory as it offers absolutely no reason for the cause behind gravity.
Steven
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Excellent explanation.
That said, it's possible to go further than this. The idea that space-time is 'really' 'curved' only arises because we look at the maths of GR and insist on interpreting it in a way that makes intuitive sense to us in the context of the low energy conditions we usually experience.
Personally I find that a very useful way of thinking about it, however it's worth remembering that the physical theory is just a bunch of equations expressing relationships between directly observable quantities, and the actual curvature of space-time is only indirectly observed.
Occasionally it becomes very important to remember that the interpretation attaching to the indirect things is not necessarily real, just useful. A good example of this is the idea of the electromagnetic field. Very important in classical EM, but starts to look distinctly less real in the Feynmann approach (glossing over a lot of technical stuff).