if you start with 26-D spacetime, compactification may be how particles are formed in 10-D. Compactify 10-D and you may get axions or Dark Matter. I do not know of a reverse process.
In my personal theory, if the universe is in 26 dimensions, then within the singularity of a black hole you can pack all the phase space necessary to form an entire universe in 4-D.
The proof of this is to take the 1/22th root of the size of the universe. So the universe is say 100 billion light years in size, and a light year is 3x10^^10 cm/sx365daysx24hrs/dayx3600sec/hr.
Notice that the units cancel out to give you the size of the universe in cm.
Opps. This is the distance across the universe. Its volume is pi/6times this distance cubed, or
This is not the amount of phase space as one volume of phase phase is a Planck volume or
The amount of phase space in the universe is then
V/v=10^^196 planck volumes
So when this many Planck volumes is packed into 24 dimensions (2 are time-like), the resulting volume is
where L is the extent of the volume in planck scales. So to find L you take the 24th root of
The result is 10^^196/24=10^^44/3=3X10^^11
Now a planck scale is 10^^-33 cm
So the size of the entire universe when packed into 26-D is
This is much smaller than the size of an electron and we presume that it could fit into a black hole singularity, even if the full universe were much larger.
So bottomline, the answer to your question is that space is not created between its existence in a black hole singularity to its existence as an entire universe.
What must be true, but there is not yet a theory that demonstrates this, is that phase space is created in the unified field inside a black hole singularity.
This BTW proves that the universe is 26-D as if you try the same calculation with only 10-D, you cannot fit the phase space of a unIverse inside the singularity.