Comoving Reference Frame in Cosmology

[Arman777]

In cosmology, the preferred reference frame is the comoving rest frame. I am trying to understand why we are using this frame and not another one. The only reason I could come with is this.

Since the expansion of the universe is homogeneous and isotropic it seems our best choice is using the comoving coordinates. However, I am looking for a more mathematical description which suggests that the comoving coordinates are the best coordinate for an expanding universe. Any suggestions?

 

[PeterDonis]

I am looking for a more mathematical description

"Homogeneous" and "isotropic" are mathematical descriptions. You just haven't written down the explicit math that those terms refer to.

 

[Arman777]

You just haven't written down the explicit math that those terms refer to.

That make sense, thanks