[ben_w]

> Can you point to real physical process which causes stretching or bending of the mathematical abstraction?

"General relativity" as we keep telling you.

> I cannot see objects smaller than a star or galaxy with naked eye.

Only a factor of about a trillion in the size of those two things.

> However, we can see light stretched to the microwave range.

With your eyes? No. And certainly not through your window, whose own thermal emissions relative to the CMB makes your previous claim roughly as unphysical as saying you can look through the sun's photosphere to see Jupiter during an occultation.

[oneshtein]

General Relativity is a mathematical model. Model needs mapping between physical world and model.

[ben_w]

My phone's GPS only works because that mapping keeps being better than anything else we've tested on that scale.

The atomic clocks (as I mentioned in another comment) demonstrating gravitational time dilation within a building is another fun example.

[oneshtein]

Your phone works because engineers did it.

I see strong annual signal in GPS: https://link.springer.com/article/10.1007/s10291-017-0686-6 .

Why it there?

[ben_w]

> Your phone works because engineers did it.

The engineers implemented results from GR.

> Why it there?

Not that it matters, but the answer is in the introduction.