1.5k citations · 3.3k across the 33 of their papers we have counts for
12 papers · 1 filter
Rapidly Descending Dark Energy and the End of Cosmic Expansion
Cosmin Andrei, Anna Ijjas, Paul J. Steinhardt
If dark energy is a form of quintessence driven by a scalar field evolving down a monotonically decreasing potential that passes sufficiently below zero, the universe is…
Astro2020 APC White Paper: The need for better tools to design future CMB experiments
G. Rocha, A. J. Banday, R. Belen Barreiro +27
This white paper addresses key challenges for the design of next-decade Cosmic Microwave Background (CMB) experiments, and for assessing their capability to extract cosmological in…
The Simons Observatory: Science goals and forecasts
The Simons Observatory Collaboration, Peter Ade, James Aguirre +247
The Simons Observatory (SO) is a new cosmic microwave background experiment being built on Cerro Toco in Chile, due to begin observations in the early 2020s. We describe the scient…
Bouncing Cosmology made simple
Anna Ijjas, Paul J. Steinhardt
We introduce the "wedge diagram," an intuitive way to illustrate how cosmological models with a classical (non-singular) bounce generically resolve fundamental problems in cosmolog…
Cyclic completion of the anamorphic universe
Anna Ijjas
Cyclic models of the universe have the advantage of avoiding initial conditions problems related to postulating any sort of beginning in time. To date, the only known viable exampl…
Implications of Planck2015 for inflationary, ekpyrotic and anamorphic bouncing cosmologies
Anna Ijjas, Paul J. Steinhardt
The results from Planck2015, when combined with earlier observations from WMAP, ACT, SPT and other experiments, were the first observations to disfavor the "classic" inflationary p…
The anamorphic universe
Anna Ijjas, Paul J. Steinhardt
We introduce "anamorphic" cosmology, an approach for explaining the smoothness and flatness of the universe on large scales and the generation of a nearly scale-invariant spectrum…
Scale-invariant perturbations in ekpyrotic cosmologies without fine-tuning of initial conditions
Aaron M. Levy, Anna Ijjas, Paul J. Steinhardt
Ekpyrotic bouncing cosmologies have been proposed as alternatives to inflation. In these scenarios, the universe is smoothed and flattened during a period of slow contraction prece…
A general mechanism for producing scale-invariant perturbations and small non-Gaussianity in ekpyrotic models
Anna Ijjas, Jean-Luc Lehners, Paul J. Steinhardt
We explore a new type of entropic mechanism for generating density perturbations in a contracting phase in which there are two scalar fields, but only one has a steep negative pote…
Inflationary schism after Planck2013
Anna Ijjas, Paul J. Steinhardt, Abraham Loeb
Classic inflation, the theory described in textbooks, is based on the idea that, beginning from typical initial conditions and assuming a simple inflaton potential with a minimum o…
Scale-free primordial cosmology
Anna Ijjas, Paul J. Steinhardt, Abraham Loeb
The large-scale structure of the universe suggests that the physics underlying its early evolution is scale-free. This was the historic motivation for the Harrison-Zel'dovich-Peebl…
Inflationary paradigm in trouble after Planck2013
Anna Ijjas, Paul J. Steinhardt, Abraham Loeb
Recent results from the Planck satellite combined with earlier observations from WMAP, ACT, SPT and other experiments eliminate a wide spectrum of more complex inflationary models…