Answer
I'm not sure that there is one definitive answer. Some theorists might say that space is finite and unbounded (no boundaries). This is roughly like the idea that the surface of a globe is finite and unbounded. You can just keep going and going, and you don't come to the "edge".
This is not entirely accurate for several reasons. It is true that space has been viewed as flat, spherical, or saddle shaped in keeping with gravity as curved space-time. Both that flat and saddle would result in walled in space at the the edge of the manifold. However there are more reasons than merely gravity to consider space to be "Finite Yet Unbounded" but what does this mean percisely? No One Really Knows. Yet it is entirely true that you could not in any rational way come to a boundary in space; like a wall with a sign reading "Please turn back now because you run out of space." So let's think together for moment. An Infinite Euclidean Manifold will also not do since it would have an inaccesable, fuzzy boundary. What we need is space that is the same everywhere with no boundary. If you try to twist space to find the manifold you will soon discover that you would have to turn a sphere inside-out with intersecting of its surface. The only way to do it is to make time to be the radius and space its surface like this:
"Space Is Finite But Unbounded"
This is a Spherical Knot Manifold
(x, y, z) = τ(θ, φ, ψ, t)(θ, φ, ψ) = (τ(θ, φ, ψ, t)θ, τ(θ, φ, ψ, t)φ, (θ, φ, ψ, t)ψ)
The radius: τ(θ, φ, ψ, t) = ∫ v dt
is derived from time, and θ, φ, ψ, angles measured in radians so that each term is like S = rθ part of a circumference of a circle (when the angle is θ = 2π radians you have a whole circle).
It's simple because of The Heisenberg Uncertainty Principle
Δp Δx ≥ ħ /2 or ΔE Δt ≥ ħ /2
The Nothing Universe -------> Space ---------> Matter ; End of story "Complete Unified Theory of Everything".
Now everything makes sense. Space is curved hyperperpendicularly to time much like a magnetic field. Lines are curved around a charge perpendicular to the electric field lines. In this model one could even begin to see further identity/unity into time and space. At The Point Universe Stage the universe would be in a state of Complete Destructive Interference that would be The Nothing Universe. This is possible owing to the unique geometry of a Spherical Knot Manifold since it has only interior points, no exterior points nor boundary points so it would be the opposite of points in space which have no interior points.
Further it is quite reasonable to think that there were several big bangs until a stable universe formed; one with the right mass not to collapse as in a big crunch. Any harmonic oscillation would have to be a random Quantum Harmonic Oscillation. But it is quantumly random and would come to rest in the form of a Stable Universe.
One further insight on this is:
The basic outline in function notation is β:Ø ----> U where Ø = { }.
Everything exists with "ignition (1)" including all math since Nothing is Nothing: Ø = { } ≠ {math} . Therefore the greatest unified theory is at the heart of thesingularity. So the payoff is bigger than you could ever imagine.
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