08-30-2016, 12:36 PM

" ... equally, we can choose a frame and identify that as the absolute reference frame, as in Lorentzian Relativity."

That violates the Einstein principle of relativity.

"The obvious absolute frame to choose, for every spacetime point, is the one that makes the Microwave Background Radiation isotropic."

Every arbitrarily chosen point of four dimension spacetime in an isotropically expanding universe is the origin of CMB.

"Note the fixed reference frame can exist without ether, but it's harder to imagine ether without the fixed frame."

Why? The coordinate point at infinity isn't fixed, and survives nicely with an ether. Just not a 'luminiferous" ether, due to the limiting speed of light -- a spacetime ether is unbounded.

That violates the Einstein principle of relativity.

"The obvious absolute frame to choose, for every spacetime point, is the one that makes the Microwave Background Radiation isotropic."

Every arbitrarily chosen point of four dimension spacetime in an isotropically expanding universe is the origin of CMB.

"Note the fixed reference frame can exist without ether, but it's harder to imagine ether without the fixed frame."

Why? The coordinate point at infinity isn't fixed, and survives nicely with an ether. Just not a 'luminiferous" ether, due to the limiting speed of light -- a spacetime ether is unbounded.