What if the universe is shrinking instead of expanding?

[Tobbzn]

I'm a first year physics student, and I've recently read up on some wikipedia cosmology and talked to some people who are far more experienced in this field than I am. I've come across things such as the balloon analogy, which made sort of sense until I heard that the universe doesn't expand into anything.

So, space between objects expands (and accelerated too), but the universe doesn't expand into anything? That doesn't sound right. Seems like a paradox. Now, I know there are paradoxes in nature, but the more I thought about it, the more I thought it seemed like it implied a different explanation.

Now, imagine a spherical glass ball in which the universe lies. Imagine, if you will, a cube grid stretching through it. Now, if space expands everywhere, then the balloon analogy would imply more grid space between points, but if the universe doesn't expand into anything, in order to fit the extra grid cubes, you'd have to shrink each cube in size in comparison to the absolute size of the entire universe.

What if that's what is happening? It would explain why space seems to expand but the universe doesn't expand into anything (On a related note, how did we find that out?), if, in fact, we were instead shrinking (and, I suppose, diminishing the speed of light by an equal factor).

When I asked this question to a friend, I was directed to ask at this forum, and I hope I could get some clarification on this subject.

 

[Hurkyl]

You can make things look pretty much any way you want by "measuring" things in ways unrelated to the geometry of space-time.

 

[Tobbzn]

Mayhaps so, but even if this is an inconsequential explanation, it seems less paradoxical to me.

 

[Chalnoth]

There isn't actually any difference between the universe expanding and atoms getting smaller. The two scenarios are mathematically identical.

We just don't talk about atoms getting smaller because we measure everything around us in terms of the size of atoms, and thus consider them to be constant in size.

 

[Tobbzn]

Then what is the logical correlation between space expanding and the universe not expanding?

 

[Chalnoth]

Then what is the logical correlation between space expanding and the universe not expanding?

Well, you have one or the other. You can't sensibly talk about both happening under the same description. Either space is expanding (and, in turn, so is the universe), or space isn't expanding (and neither is the universe), but atoms are shrinking.

 

[Chronos]

The problem is the universe is observationally finite, but, not necessarily spatially finite.