I have read that Einstein's formulation of gravity [tex]G_{ab}=\frac{8 \pi G}{c^4}T_{ab}[/tex] is analogous to the differential form of Newton's version [tex]\nabla ^2 \phi = 4 \pi G \rho[/tex] with the metric tensor and energy-momentum tensor in the modern form playing the same roles as gravitational potential and density in the classical one, respectively.(adsbygoogle = window.adsbygoogle || []).push({});

My question: why did the 4 become an 8?

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# About poisson's equation

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