Tuesday, July 28, 2015

Paul Steinhardt Introduces The Anamorphic Universe

Paul Steinhardt has a new paper on the arXiv. Here is the abstract.

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 of adiabatic density perturbations. The defining feature is a smoothing phase that acts like a contracting universe based on some Weyl frame-invariant criteria and an expanding universe based on other frame-invariant criteria. An advantage of the contracting aspects is that it is possible to avoid the multiverse and measure problems that arise in inflationary models. Unlike ekpyrotic models, anamorphic models can be constructed using only a single field and can generate a nearly scale-invariant spectrum of tensor perturbations. Anamorphic models also differ from pre-big bang and matter bounce models that do not explain the smoothness. We present some examples of cosmological models that incorporate an anamorphic smoothing phase

Saturday, July 18, 2015

Physics Q&A #1: Discrete Spacetime

I spend a lot of time on this blog explaining a physical spacetime model and the underlying metaphysics. In this series of posts, each entry poses a physics question for the spacetime model, along with the answer. A separate series of posts answers metaphysics questions.

Physics Question #1. The model says spacetime is made of discrete points. OK, then what's between them? What keeps them apart? For that matter, what keeps them from flying away from each other? The first question has been used as a put-down ever since someone first suggested that spacetime might be discrete. The other questions are used in the same way. Actually, the answers to these questions are simple, although not obvious.