I know the pat explanation about expanding space is not expanding into space, but I keep asking in order to show you and other BB believers that it is not logical for finite space to have no form, to be expanding into nothing. Nothing does not exist, so given that this BB universe exists, it either exists in infinite space, or nothing. To keep saying the question of 'outside' is invalid is a cop out.

One problem is that you have a very Euclidean view of space. But we know that this need not be the case.

If the universe is spatially flat, then space is more like a higher dimensional sphere: it looks flat close by but curves as yo go further away.

if you want to go a strict general relativity answer to your question, space expands *into the future*. This is quite literally the best answer in that the four dimensional vectors that point in the direction of a larger universe point into the future.

Space is NOT expanding 'into nothing'. Space is literally all that exists at a specific time. it is a time slice of spacetime.

Also, we do not know whether space (as a whole) is finite or not. Again, it need not be in the context of an expanding universe.

Your assumption is that space itself is infinite. But that is precisely the issue at hand: is it infinite or is it finite (and curved)?

As an example of how a curved space would work, think by analogy with the surface of the Earth. Any direction you take, you will eventually return to the same location if you keep going long enough.

This is how a finite volume of space would work: any direction you decide to go, you will eventually return to the starting point if you travel long enough. No boundaries, each point 'looks' the same as every other point. And yet, because of curvature, the total volume is finite.

And, in this context, expanding space means that the total volume at one time is larger than at previous times.

It is similar to the question of what existed before the BB, if you agree there is no nothing, then it had to have began somewhere in infinite space.

I know you will then say time had not begun so the question is invalid, but it's another cop out.

Why is it a cop out? Why do you assume that time goes infinitely into the past? That is an assumption that may or may not be true, but the answer is only to be found through observation because both options are logically plausible. There is NOTHING in logic that dictates that space must be finite in volume.

The logic on which I lean is human logic, if we discard that, then we can not have a reasonable discussion.

Logic is not the relevant factor here. Logic alone only tells whether certain arguments are valid or not. it does not and cannot say whether the basic assumptions about space and time are themselves true.

So, for example, the logic that Aristotle used would be considered to be flawed and confused by today's standards. A *lot* of basic logic was done about 100 years ago by Godel, Hilbert, Skolem, Lowenheim, and others. This *is* human logic (it certainly wasn't done by non-humans). But it goes deeper and shows the mistakes of those of the past.

Logic is *only* those things that use terms like 'if..then, or, and, if and only if, for all, there exists'. Space and time are simply not something that logic alone addresses.

If there were a multiverse, then what would exist between universes? In this multiverse scenario, assuming there would be universes sufficiently developed whereby very advanced intelligent life could detect the BB beginning of new universes, these new BBs would be referenced to spacetime.

I will never accept BBT until I understand how and why it came into being!

And you assume there is a *reason* why it came into being. You assume there was a time before the BB and that is precisely what the BB model says is not the case.