11D + 11D OPPOSITE BRANE (11D MODEL)

The specific theoretical model of an "11D + 11D opposite model universe with 3D balloon inflation" is not a standard or established theory in physics. It appears to be a unique combination of various concepts from theoretical cosmology and M-theory.
However, mainstream theoretical physics does incorporate the individual elements you mentioned into various brane cosmology models:
1. 11 Dimensions (11D)
M-Theory: The most widely recognized framework operating in 11 dimensions is M-theory, which serves as a unifying theory for all five superstring theories (which exist in 10 dimensions).
Dimensions: These 11 dimensions typically consist of 10 spatial dimensions and one time dimension. The extra seven dimensions are usually hypothesized to be "compactified" (curled up to a size near the Planck length, making them unobservable) or our universe is localized on a brane floating in a higher-dimensional "bulk" space.
2. "Opposite" Branes
Brane Worlds: In some M-theory-derived models, our 3D universe is a 3-dimensional brane (a "3D balloon") existing in a higher-dimensional space (e.g., a 4D or 5D bulk).
Cyclic Universe Models: Some speculative models, particularly Ekpyrotic or cyclic universe scenarios, suggest the existence of a "mirror" or "opposite" brane. These two parallel branes might collide periodically, causing a Big Bang and a subsequent cycle of expansion and contraction. The idea of an "opposite" brane often relates to having opposing energy densities or simply being a mirror universe in the bulk space.
3. 3D Balloon Inflation
Cosmic Inflation: The standard cosmological model uses the theory of cosmic inflation to explain why our observable universe is so uniform and flat on large scales.
Balloon Analogy: The expansion of space during inflation is commonly described using the "inflating balloon" analogy. In this analogy, the surface of the balloon is our 3D space, which expands without a center on its surface. This expansion is thought to have occurred rapidly in the very early universe, dramatically smoothing out any initial curvature.
Summary of the Concept
While a single, recognized model does not perfectly match your description, a viable (though highly speculative) theoretical framework could combine these elements:
Our universe is a 3D brane (the "balloon surface").
It is embedded in an 11D spacetime (10 spatial + 1 time dimension).
Its expansion is driven by a mechanism (inflation) that can be visualized with the balloon analogy.
There could be another, "opposite" brane in the 11D bulk, perhaps involved in a cyclic process.
The mathematical consistency and testability of such a complex, high-dimensional model remain significant challenges for modern physics