How can something infinite be quantitized?

Question

I read that there are x number of atoms in the universe.

I also read that the universe is infinite.

How can there be a finite number of atoms in an infinite space? Wouldn't that mean atoms would be so rare that statistically, atoms would never ever come into any kind of close proximity to each other? Or would it mean that were in the mist of an atom soup, and beyond it is space but an infinite amount of it, giving us basically an 'edge'?

Answer 1

You can't believe everything you read, even if it's called science.

The estimates of the number of atoms are simply estimates of the 'observable universe'. We have no way of knowing about events so distant from us in time and space that light has not had time to reach us.

We know atoms are not so rare, because we observe them in close proximity.

In a way, you are asking what's beyond the universe.

The main options:

1. Nothing. Just define 'universe' so it includes everything.

2. Space containing no matter and perhaps even no energy.

3. There is no such thing. Space exists only as relationships between matter, so if there is no matter, there is no space. I'm not joking. Some scientists seriously consider this.

4. There is no such thing. Space is expanding along with the material universe.

5. There is no such thing. The universe is a closed topology. I don't think there is any particular evidence to support this.

6. Conjecture whatever you like. We'll never know. It's beyond our event horizon. Imagine parallel universes if that tickles your fancy.

Answer 2

The observable universe is finite; that is the part from which light can reach us during the 13.7 billion years since the Big Bang. There is a larger, infinite universe beyond that that we cannot observe because of the finite speed of light (though we see a bit more of it every day!). But the finite part that we can observe of course has a finite number of atoms... about 10^80, we think.

Answer 3

Atoms are matter. The universe is space. You can have a finite number of atoms distributed within an infinite space.

Answer 4

You can't have both, unless you posit that the "untenanted" universe contains not a speck of matter (an infinite vacuum).
Even the thinnest parts of galaxies contain some atoms.
So the edge would be where the galaxies end.
But still, wouldn't the number of galaxies be infinite?
A conumdrum and on of the unsolved mysteries of the universe.