Modeling and Testing Screening Mechanisms in the Laboratory and in Space

Round 1

Reviewer 1 Report

Comments for author File: Comments.pdf

Author Response

We thank the Referee for carefully reading our manuscript, and for providing useful feedback. Below, we provide our responses and the summary of modifications.

As we state in our introduction, our primary interest in this review article has been the screening mechanisms in theories of modified gravity (particularly, scalar-tensor extensions of Einstein's theory of General Relativity). We were invited by the guest editor to write this review precisely about screening mechanisms, rather than tests of gravity in a very broad context. We agree with the Referee that tests of gravity have a very long history. However, for the purposes of our review, we would prefer to stay focused on recent developments relevant to gravity and cosmology communities. We believe the historical context would be suitable for a separate work.

The field of screening mechanisms itself is very broad and, as we mention in our introduction, has been reviewed in a number of excellent papers. However, even though a significant effort of the community is directed toward developing robust methods to model and test screened fifth forces, there still has not been an attempt to review the technical tools used for modeling the non-linear phenomena inherently present in screening mechanisms. We, therefore, believe that our objective of summarizing such efforts is well-motivated and very useful for the modified gravity community. We clearly state the motivation behind this work in our abstract and introduction. 

We are very thankful for the provided references regarding the Casimir experiments. We have now added 11 new references to pioneering and modern Casimir force measurements, as well as assessments of proximity-force approximations (please see our new Refs. [79,80,83,84,86,87,88,91,92,93,94]).

We would like to stress that our paper is very specialized, and, as mentioned above, we would like to keep the discussion relevant to tests of screening mechanisms. In this regard, although we now mention the systematic effects highlighted by the Referee including the suggested references, we do not extend further on these problems in the context of quantum-field-theoretical Casimir forces. We rather focus on reviewing efforts directed towards modeling the non-linear dynamics of coupled fifth-forces in Casimir force experiments, however, we direct the reader to the relevant references for further detail.

Best regards,
The authors

Reviewer 2 Report

The basic categories of screening mechanisms are presented in this succinct summary, along with tests conducted on them in both laboratory and astrophysical settings. They put a lot of emphasis on going over the numerical and technical components of modeling the non-linear dynamics of screening through testing utilizing lab experiments and astrophysical systems, like stars, galaxies, and dark matter halos. Understanding the nature of gravitational interactions will be greatly enhanced by testing modified gravity theories in non-linear regimes. Simultaneously, robust modeling of non-linear events is frequently quite difficult, necessitating significant cross-domain effort. Approximate methods must be replaced with more precise ones because astrophysical and laboratory experiments are becoming much more precise. I recommend publishing this short review in the present form.

Author Response

We would like to thank the Referee for their positive feedback.

Round 2

Reviewer 1 Report

The revised version contains significant improvements, although I am not qualified enough to comment on the more astrophysical-oriented component. In my view there is tension between writing a review paper and considering it as a 'specialized paper'. The main goal of any review, in my opinion, is to provide a broader context, including the genesis of the subfield (which does not imply to write a long essay of history, rather to pinpoint the crucial contributions with proper credit to the pioneers), and to 'connect the dots', bridging the subject to other subfields or nearby areas. 

Having written so, I respect the opinions of the Authors and I have no objection to recommend this revised version for publication in Universe.