How is the universe constantly expanding ?


I don’t understand the concept behind the fact that the universe is infinite and that it is always expanding.

In my mind: something expanding assumes that there is space for it to go into, and if that space existed previously, it can’t really be considered an expansion since it was already there.

Perhaps I have misunderstood what is meant through the term ‘expansion’ in this case or made an incorrect assumption, I’d appreciate if anyone could clarify the process for me.

In: 1

You are thinking of the expansion as if the universe is a room and the walls are moving away from center making it larger. What’s actually happening is the universe is like a giant balloon and galaxies are dots on the balloon. As the balloon expands and fills with air, the dots move away from each other, but aren’t moving along the ballon. Things in the universe, like galaxies, are becoming more distant. The space between things is what is expanding, increasing the scale of the universe.

first of all, this concept is not easy to grasp, so its completely normal that you are confused.

basically, space is not expanding into anything, but rather space itself is growing. This is really weird. Imagine an infinitely large bed sheet getting streched. Everything moves further apart, because the space between stuff is getting “bigger”. Its not that you add fabric at the sides (since there are no sides, it is infinitely big), but the fabric itself gets pulled apart. Note that this is a very ELI5 explanation.

We don’t know.

Several comments have addressed a mechanical flaw with your question in regards to expansion as it relates to the distance between things versus expansion into a predefined space which is fair enough but your actual question was “how the fuck is it happening?” and we legitimately don’t know.

Not a topic that can really be addressed in ELI5.

Dont think of universe as a ball that’s growing in size.

The best way to visualize it is this. Imagine a balloon. But the universe isnt inside of the balloon, the universe is the 2d surface of the balloon.(its 2d only for visualization purposes, you can intuitively translate this to 3d later).

Now, you can walk on the surface of the balloon forever, but youll never reach “the end” or the edge. Same goes for the universe.

And what universe expansion looks like is same as how the surface of the balloon is expanding when you blow it up. Every point in space is expanding and getting away from one another at the same time.

A mind boggling question, what created all the matter in the first place, there must have been a time where there was no matter & space was completely empty of everything, just a one in a million chance there is some sort of afterlife & we’ll find out.