Science is the
communication of
testable models of
repetable experience.
Like the 'real' reality in The Matrix, or the 'noumeal' reality posited by Kant, once you add one extra layer of 'real' reality, why not add an infinte number? Why have any at all? The tests of repeatability and faslsifiability for hypotheses avoids pure phenomenology or solipsism which most people offer as a reason for the concept of reality.
The function of such a concept is for easing communication about our models...but it is unprovable, and unnecessary.
All people have a basic faith in their memory, which allows us to create models for understanding our experiences, but like belief in God, the belief in an objective Universe is completely unprovable, because all evidence can only be more experience - there is no way to falsify the notion, or prove it. This type of concept is known as an untestable hypothesis
This verbose craziness brought to you at the hands of the Freelance Nodeshell Rescue Team