Primordial Nucleosynthesis in the Rh = ct cosmology: Pouring cold water
  on the Simmering Universe
  Primordial nucleosynthesis is rightly hailed as one of the great successes of
the standard cosmological model. Here we consider the initial forging of
elements in the recently proposed Rh = ct universe, a cosmology that demands
linear evolution of the scale factor. Such a universe cools extremely slowly
compared to standard cosmologies, considerably depleting the available neutrons
during nucleosynthesis; this has significant implications for the resultant
primordial abundances of elements, predicting a minuscule quantity of helium
which is profoundly at odds with observations. The production of helium can be
enhanced in such a "simmering universe" by boosting the baryon to photon ratio,
although more than an order of magnitude increase is required to bring the
helium mass fraction into accordance with observations. However, in this
scenario, the prolonged period of nucleosynthesis results of the efficient
cooking of lighter into heavier elements, impacting the resultant abundances of
all elements so that, other than hydrogen and helium, there are virtually no
light elements present in the universe. Without the addition of substantial new
physics in the early universe, it is difficult to see how the Rh = ct universe
can be considered a viable cosmological model.
