INFLATION IN MODELS WITHOUT A BIG-BANG

A universe with an exponential expansion is theoretically acceptable i n Einstein's general relativity, and also in general scalar-tensor the ories as well as in scalar-tetradic theories. It may even be, still, a n acceptable description if another theory, rather than standard gener al relativity is physically relevant because the way the universe expa nds, notwithstanding noteworthy advances in cosmological observations, remains a subject of debate. The only undisputed aspect now seems to be the interpretation of observations that point to its actual expansi on. This paper aims to show the possible significance of having a univ erse expand exponentially in the different theories mentioned above: T he fact that these models have a common geometry, that is, the same me tric and expansion factor but their physical predictions are, of cours e, theory dependent.