Review Reports

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The report is attached.

Comments for author File: Comments.pdf

Author Response

Deal Editor,

My Response to Referee 1 report can be found in the attached file.

Sincerely,

Meir Shimon

 

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The underlying premise of the paper is within the standard cosmological picture: that our observable universe is a tiny fraction of a much larger (causally) connected parent Universe. It is shown that more general solutions, beyond standard inflation, can address the classical horizon and flatness problems. While inflation provides a dynamical smoothing mechanism that relies on unknown high energy physics, the proposal of the authors provides a resolution that is primarily geometric: homogeneity and flatness arise because we observe only a tiny fraction of a much larger Universe. The role of matter and gravitational entropy are considered in both cases, standard inflation and geometric resolution. For a globally closed Universe, it is shown that the curvature radius defines the size of the Universe. When the latter is much larger than the observable Universe, such a model is essentially indistinguishable from a spatially flat one. The paper adopts a "Small Patch Hypothesis", which proposes the parent Universe is sufficiently conformally older than the observable universe to sufficiently explain the apparent horizon problem. The authors adopt an ansatz power spectrum that logarithmically runs with scale over cosmological and ultra-Hubble+ scale. The authors demonstrate that a wide class of power spectrum alternatives are also possible in addition to logarithmic, all of which are well-approximated within the observable universe by red-tilted power law. It is remarked that currently the CMB only samples 3 to 4 decades in scale, providing insufficient information to presently rule out the proposed logarithmic running power law. Future tests are proposed that would be able to falsify geometric solutions. The paper is well written, the sections well organized, and the paper is succinct. It is very insightful and suggests a new line of cosmological research offering a possible alternative to standard inflation. I support its publication in current form.

Author Response

Dear Editor,

My response to the report of Referee 2 can be found in the attached file.

Sincerely,

Meir Shimon

 

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

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