Gibsense, I think it might help if we pretended that I had not seen your posts about hyperspheres, and just wanted to explain use of my analogy, in the light of my having had it around in my head for a while now.
I mean no disrespect to your ideas. I just do not think they help in understanding what I am trying to convey. My analogy may differ slightly from your ideas - I think they are fine, but just tend to overcomplicate what I intend. In other words, I have no criticism at all regarding your 4D statements - they are just not helpful (IMHO) in my analogy.
Let us consider a mathematical sphere. Considering a bubble is not helpful, as a bubble has two surfaces containing a thin film of aqueous medium. (Water plus surfactant).
Let us, just for the sake of this analogy, consider that this sphere (surface) represents the universe for a flatlander. I have suggested elsewhere that expansion of the universe only makes sense to a being able to appreciate one more dimension than the flatlander.
Thus, considering a larger spherical surface represents the view of his universe expanding.
It is not a picture over time, per se, since time is included in the universe.
It supports my suggestion that expansion of 'our' universe can only be understood by appreciation of a higher dimension than is available to us.
There are organisms which live on water surfaces, so the idea is not so outlandish.
If we use a bubble, the thickness starts causing problems which are not really relevant, but we can adjust to that if we just think there is a thickness wherein they live, if necessary.
The only point I want to make is that expansion of the universe can be better understood if we consider the abilities of a being with higher understanding of dimensions.
Is that OK?
Cat