At best, you are claiming that swebs' argument was correct because there is a different argument for the point he claimed has been demonstrated - but that is, as you say, "a very different thing." My original objection to that argument stands, and you have agreed that it does!
> Demonstrating the opposite is an very different thing from failing to demonstrating a difference at all.
Who is making any claim about demonstrating the opposite? You can see from my original post that I agree that spacetime is expanding; I merely disagree with swebs' argument for claiming to know that it is.
>> What set of measurements and calculation do you have in mind that avoid this circularity?
> Any measurements that would actually work, I think.
In that case, you will have no difficulty in stating, or providing citations for, the actual measurements and calculation that get the job done - if any such set of measurements exist, that is. Otherwise, your reply is equivalent to "I don't know."
My point is that I do not think that there is any set of deduced remote measurements that a) show, as a certainty, that space itself is expanding, and b) can be deduced without implicitly or explicitly assuming a position on the issue. Current cosmology expects that the large-scale measurements will show the same results as from Earth (e.g. the same Hubble constant, if and only if you derive it using the same assumption about space itself expanding), but the absence of a difference between there and Earth would fail to satisfy a).
Furthermore, I notice that you have still not made clear which redshift measurements support your claim that the issue has been resolved experimentally. A citation would be sufficient.
I probably could have been more explicit. To be clear, the opposites here are 'the big bang is an expansion of spacetime' and 'the big bang is an expansion in spacetime.' Swebs claimed the diagram showed the former, but it acually literally shows an expansion in space (which, it so happens, also works for an expansion of space, and so does not, as it stands, show a way to choose between the two.)
> Demonstrating the opposite is an very different thing from failing to demonstrating a difference at all.
Who is making any claim about demonstrating the opposite? You can see from my original post that I agree that spacetime is expanding; I merely disagree with swebs' argument for claiming to know that it is.
>> What set of measurements and calculation do you have in mind that avoid this circularity?
> Any measurements that would actually work, I think.
In that case, you will have no difficulty in stating, or providing citations for, the actual measurements and calculation that get the job done - if any such set of measurements exist, that is. Otherwise, your reply is equivalent to "I don't know."
My point is that I do not think that there is any set of deduced remote measurements that a) show, as a certainty, that space itself is expanding, and b) can be deduced without implicitly or explicitly assuming a position on the issue. Current cosmology expects that the large-scale measurements will show the same results as from Earth (e.g. the same Hubble constant, if and only if you derive it using the same assumption about space itself expanding), but the absence of a difference between there and Earth would fail to satisfy a).
Furthermore, I notice that you have still not made clear which redshift measurements support your claim that the issue has been resolved experimentally. A citation would be sufficient.