How is the universe constantly expanding ?

Question

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

Answer 1

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.