Symbol ddotx^mu

The passage around this formula

…of spacetime itself, and a body in free fall — no rocket, no resistance — simply follows the straightest available route through that curved geometry, a geodesic, obeying the same one-line logic as light and no other: $\ddot{x}^\mu$ + $\Gamma^\mu_{\alpha\beta}$$\dot{x}^\alpha$$\dot{x}^\beta$ = 0 , the geodesic equation, in which curvature has replaced force as the reason anything bends [ 11 ] . Newton needed a force to explain why a thrown ball leaves a straight line; Einstein needed nothing but geometry, because the…

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