Accelerating universe

Accelerating universe is a term for the idea that our universe is undergoing rapid expansion. In the late 1990s, observations of type I supernova produced an unexpected result that the expansion of the universe appears to be accelerating. These observations appear more firm as new data has appeared. This means that the speed with which a distant galaxy recedes from us increases over time.

This current acceleration phase is a continuation of the Universe's alternating (acceleration->deceleration->acceleration) history of expansion. The initial acceleration phase, referred to as 'inflation', was followed by a deceleration phase and the current acceleration phase. This alternating expansion is, quite literally, a reverberation of the Big Bang - a gravity wave in time that we can see by looking out into space.

The question is: Where do things go from here? It has been suggested that the expansion will continue to accelerate, to the point that the Universe will end in a Big Rip. Alternatively, the Universe may be a self-regulating, nonlinear system - as might be evidenced by a plot of the expansion rate versus time.

The mechanism for this self-regulation is a feedback loop. We know that the expansion rate has an effect on the rate that matter (i.e., mass) comes into the observable universe. What hasn't been recognized is a second relationship involving the expansion rate of the Universe (exp') and the mass of the observable universe (Mou). That relationship is: exp' = Mou'/Mou, where Mou' is dMou/dt. This second relationship can be derived solely from Einstein's pronouncement that "Space without matter is meaningless".

The result of these two relationships is a self-regulating, non-Ripping Universe.