- #1

matteo86bo

- 60

- 0

[itex]\nabla^2\phi=-4\pi G\rho[/itex]

But I was wondering if, mathematically, we can write the same equation for a scalar field which scale as [itex]r^{-2}[/itex].

Here is the thing. When you deal with gravity, the Poisson equation is derived from the Gauss's law for gravity:

[itex]\int_{\partial V}\dfrac{GM}{r^2}\cdot d\vec{S}=4\pi G M[/itex]

Then we apply the Gauss's law and we get the differential form of the Poisson equation:

[itex]\nabla\cdot\vec{f}=4\pi G\rho[/itex]

My question is: suppose that we have a scalar field

[itex]p=\dfrac{L}{4\pi r^2}[/itex]

Can we make an analogy between this field and the gravitational force and write a Poisson equation for this field in the following form?

[itex]\nabla\cdot \vec p=l[/itex]

where [itex]L=\int l dV[/itex]

My question might also be interpreted as: can we apply the Gauss's theorem to a scalar field?