Is it possible that there is more than one entirely correct unified field theory? As we approach a more and more solid limit to the data we can get in physics, we find that there are multiple possible explanations (although they are not whole). Is it possible that instead of a single unified theory, there are a multitude of them which all explain the whole universe and all of our explanations perfectly and that they are all mathematical mirrors of each other, thus all being different ways of saying the same thing, but they all make different predictions about things like "is there a multiverse", "are there extra curled up dimensions", etc. and them all being correct, putting the universe in a "superposition" of all of the possible explanations and their implications "outside" of our universe (if there is an "outside").
 A: After the prediction of Hawking radiation due to quantum effects at the event horizon of a black hole, it was found that the total entropy of a black hole is proportional to the surface area of the black hole.  This is an astounding theoretical discovery, because entropy as conceived by Boltzmann and other physicists prior to the prediction of Hawking radiation is based on the total number of micro states in a volume of matter that composes a macro state.
Entropy is a basic concept of physics.  To say that entropy of our 3-dimensional space can exist on a 2-dimensional surface opens the possibility that a multi-dimensional world may be describable by a lesser-dimensional theory.  This is called the holographic principle.
In theory, this would mean that the space-time in which we live emerges from something more basic.  For example, our multi-dimensional universe may emerge from a reality with fewer dimensions.
Juan Maldecena performed a theoretical exercise which shows that this is possible.  He formulated a model of 5-dimensional supergravity anti-de Sitter space (negative vacuum energy - we live in de Sitter space with positive vacuum energy), which is the "dual" of 4-dimensional flat space-time with no gravity.  "Dual" means that although the theories look different, they have the same content.  He was able to describe a 5-dimensional world with a 4-dimensional theory.  One requirement, however, is non-locality, which means that you can't match specific points in a 5-dimensional world with specific points in a 4-dimensional world.  But you can match states in time of one theory with states in time of the other theory.
So it seems that two theories can describe the same world.  But are they two versions of the same theory?  This may be a philosophical question.
