[ben_w]

> Nobody pointed to a source of energy for this "expansion" of "space".

Several have been made, the suggestions have issues.

> Usually, coordinate system doesn't expand with time.

Define "usually". Do you have experience of other universes?

> An extraordinary claim requires extraordinary evidence.

Indeed, but this comment box is too small to do the evidence justice.

Edit: that's unhelpful in retrospect, so I suggest the Youtube channel "PBS Space Time". The videos build on each other, so start at the beginning and work through the back catalogue.

> Yes, CMB emitters are much further away, at a distance of about 4Tly,

I have no idea where you got this belief from.

[oneshtein]

> Define "usually". Do you have experience of other universes?

I have experience with coordinate systems. I can bend or expand space-time on my computer all day long, to simulate reality, but I cannot do that in the real world at all.

> Indeed, but this comment box is too small to do the evidence justice.

Looking for the paper or a blog post! However, I suspect that you will just stretch evidence until it will match your model.

> I have no idea where you got this belief from.

Just by looking in the window, I see that some object are close, other are far away, then even further away, and so on, up to 4Tly. Nothing extraordinary. No Big Bangs, no FTL speeds, no hidden sources of energy of epic size, just ordinary physics.

[ben_w]

> I cannot do that in the real world at all

Sure you do, just by sitting there.

Reminds me a bit of my dad; he did radar simulation for military IFF and one of his work anecdotes was about increasing the number of decimal(!) digits of pi the software used.

He stopped boasting about that when I pointed out the extra digits were less relevant than the curvature of spacetime caused by Earth itself.

> Just by looking in the window, I see that some object are close, other are far away, then even further away, and so on, up to 4Tly

I had dreams like that once. Woke up to find I was suffering from testicular torsion.

If you seriously believe you can see 4e12 light years through your window, that's probably hallucinogens of some kind (not necessarily intentional).

[oneshtein]

> Sure you do, just by sitting there.

I 100% sure that I cannot bend or stretch imaginary coordinate system outside of my imagination. Can you point to real physical process which causes stretching or bending of the mathematical abstraction?

> If you seriously believe you can see 4e12 light years through your window, that's probably hallucinogens of some kind (not necessarily intentional).

I cannot see objects smaller than a star or galaxy with naked eye. However, we can see light stretched to the microwave range.

[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.