The alternative vision on this is that the universe has no age (since the universe did not have a begin), and the estimation of 13.7 billion years is a relative age (dating back to the most ancient event we can measure), by which it is expressed that the universe is endless in time.

(And as an explenation to this, it is to be stated that matter/energy can only be converted/transformed, but not created or destroyed, and the reasoning that time can not be said to have begun, since a beginning of any something must itself be positioned within time itself to denote something meaningfull, thereby classifying events that happen "out-side" of time as not meaningfull and not physical notions).

Note also that the Big Bang theory as a scientific theory does not prescribe that the universe began with the big bang, and that the big bang event is not the begin of time. All theories about what caused the big bang, are not strictly part of the big bang theory itself, but merely extentions to that, like the theory of cosmic inflation,or the ekpyrotic model of string theory.