Who believe which theory explains our universe, if it is close or open?
I don't know which one it is but the physics for both theories is very fascinating.
I do believe if the fabric of spacetime is compose of vibrating strands of energy,
the Theoretical physictists
maybe wasting their time, because strings are so small that some expermental physics believe it will never be tested in the lab, in this universe anyway.
So it will be a theory of Philosophy
not physics, no matter how beautiful the mathematics is.
Quantum Gravity is interesting theory, but I am not sure about this one.
String Theory:is a model of fundamental physics whose building blocks are one-dimensional extended objects (strings) rather than the zero-dimensional points (particles) that are the basis of the Standard Model of particle physics
Quantum Gravity:is the field of theoretical physics attempting to unify quantum mechanics, which describes three of the fundamental forces of nature, with general relativity, the theory of the fourth fundamental force: gravity. The ultimate goal of some is a unified framework for all fundamental forces—a "theory of everything".
Also, it is a quantum theory of gravity in which the very space that all other physics occurs in is quantized.
Spacetime is of discrete composition on Planck scales.
Or time and space comes in pieces.
Lecture notes on loop quantum gravity
For those of you who are technical or study math an physics I have posted the links of lecture notes about the two theories if you are interested, of course.