Multiverse Predictions for Habitability: Stellar and Atmospheric Habitability

Round 1

Reviewer 1 Report

Report on the paper “Multiverse Predictions for Habitability: Stellar and Atmospheric Habitability” by McCullen Sandor, Vladimir Airapetian, Luke Barnes and Geraint F. Lewis

In this paper the authors continue to discuss possibilities of placing constrains on the multiverse hypothesis by studying conditions of habitability. The paper contains new important results and in my opinion should be published.

Author Response

We thank the reviewer for their favorable appraisal.

Reviewer 2 Report

The paper is well-organized and well-written. It seems to be the last entry of a series of papers previously published by the same authors in the same Journal. That being said, I think the paper deserves publication as is. My view as a physicist is that nothing meaningful can be drawn from the multiverse hypothesis. The uncertainties behind each tiny step of the inference process are so profound that we can say everything and its contrary. Anyhow, I think any fair reviewer should be severe with blatant errors but acknowledge the hard work of the authors. I did not see any blatant error; I just do not believe in the authors' approach. 

Author Response

We appreciate the reviewer's skepticism and tolerance toward our ideas.  Their criticisms may well be right, but it is our prerogative to investigate this methodology for fruitfulness. If it turns out to be a fool's errand, well, then, we never claimed to be anything otherwise.

Reviewer 3 Report

This is an important paper that merits publication.  It contains a unique perspective on how our search for life might give us insights on the cosmology we inhabit.  I have two (minor) comments:

1.  In the discussion of atmospheres on page 8 the authors cite references that Venus' initial water content was similar to earth's.  This is a controversial topic with some recent work suggesting otherwise (M. Turbet, et al, Nature, 598, 276-280, 2021).  It would be useful to note this controversy.

2.  In that vein, the conclusions on P 18 would benefit from some suggestions of what specifically to look for as we look for life on Mars, outer planet icy moons and Venus.  What in particular measurements (life chemistry, atmospheric abundances, etc) should we look for?

Author Response

We thank the reviewer for their suggestions.  We've included these discussions and citations on pages 8 and 18, respectively.