how do you know there isn't a limit and its not gonna stop.. so that will make it so its NOT infinite

Scientists say that the universe will stop expanding when gravity becomes more powerful than whatever is causing the expansion, something they predict may never actually happen.

But... Expanding where?

...whatever is outside the Universe. Infinite, complete nothingness, presumably.

Assuming that the Universe is "stuff", the Universe is expanding into the "not stuff".

That's impossible! Because if the universe holds all that exists, and outside him there is nothing. I mean, there isn't anything. We cannot say there is nothing. The form ``is´´ is not aplicable.
Or maybe our concept of the universe is very limited.

The eter.

but what the **** is outside of the universe. how does it expand if it doesn't have an end. fffffffuuuuu-

Outside the Universe, there is nothing. Not even quantum foam, or the fabric of empty space.
It isn't even "space" because there is no such thing as here or there outside the universe.
It's just nothing. An infinite nothing.

using the phrase "outside the universe" is rather misleading. there is no such thing as "outside the universe." it's not that there's nothing out there, it's that it simply doesn't exist.