I wanted to add another reply here.

What If I wanted a really cool expandable cake like we talked about and asked you to make it for me.

But I've got a very special request.

After you bake the cake and add the frosting. I'd like to add a special flavoring. So that anyone can make this cake taste the way they'd like.

See if you can figure this out. Can I do this? What do the actual interactions look like? If I dropped the flavoring into one part of the cake, how would it distribute?

Would it be evenly? Could it ever fill the entire cake, assuming the cake never stopped growing? How would it travel from one cake molecule to the next?

This will help you to understand concepts like speed of light, and why we can't pass information faster than it.

It'll help you to understand localized events and how they interact with portions of the universe, but never the entirety of it.

Think about the relative movement. Without the flavoring now. The space between two cake molecules will always be a different relationship depending on the location of where they exist in relation to one another.

Two cake molecules side by side will always experience the same relative separation. But two molecules separated by the entire cake will always experience greater total separation because all the spaces of molecules growing in between them are cumulative.

We can pass flavor between two cake molecules, indefinitely. But assuming the cake never stops growing, what you'll find is the ability to spread the flavor becomes a function of the overall growth rate of the cake as a whole, meaning it can never keep up and that the total amount of the cake that is flavored in respect to the total cake, will always decrease.

That's odd. Because we're still getting more cake that is flavored. It's just that the amount we get will always represent a smaller percentage of the whole.

edit: We've taken our analogy in a very specific direction. One of infinite inflation of a mostly spherical object. Our universe doesn't need to meet those criteria. This is just one way to consider things. If the universe has different parameters, the interactions would inherently be different. What if our cake was really a doughnut? What if it were just a 2d plane of 3d information?

Keep these things in mind, as there are clear limitations to locking our thoughts into the ability of analogies to represent ideas.