Yes, the negative running that seems to be required on superhorizon scales in order to reconcile BICEP2 and Planck implies a maximum amplitude for curvature perturbations on these scales. Meanwhile, eternal inflation requires large density fluctuations that dominate over the classical evolution of the inflaton. These two ideas seem in conflict.Chronos said:It further asserts this is sufficient to preclude eternal inflation.
Eternal inflation is a theory in cosmology that suggests the universe has been expanding and creating new universes for an infinite amount of time. The Planck and BICEP2 experiments were conducted to study the cosmic microwave background radiation and provide evidence for the theory of inflation.
The Planck experiment found that the polarization signal previously thought to be evidence for inflation was caused by interstellar dust. The BICEP2 experiment also found that the signal was contaminated by dust, making the evidence for inflation inconclusive.
If eternal inflation is not supported by the Planck and BICEP2 experiments, it means that the theory of inflation may not be the correct explanation for the rapid expansion of the universe in the early stages. This opens up new possibilities and challenges for scientists to further understand the origins of the universe.
Yes, there are several alternative theories to eternal inflation, such as the cyclic universe model and the string theory landscape. These theories propose different explanations for the early expansion of the universe and are currently being studied by scientists.
The disfavoring of eternal inflation by the Planck and BICEP2 experiments means that scientists will need to explore other theories and gather more evidence to understand the early universe. This could lead to new discoveries and a better understanding of the origins of our universe.