Gravity = Yang–Mills

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The paper is well written, with some new results. The observation that in the double field theory some operators have additional properties not present in the single field theory is interesting. I think the `essay' is publishable. However I suggest some improvements 

(i) The new observations are not stated explicitly in the abstract and require to be highlighted in the text of the paper. 

(ii) E-H action in linearized approximation is polynomial. If the authors mean something else apart from the non-polynomial measure in the E-H action in the statement in Page 2, kindly clarify.

(iii) Perhaps the open problem of the Hull and Zweibach reference [8] should be elaborated upon.

Author Response

We thank the referee for the positive remarks and constructive suggestions 

for improvement. In response to these we had adapted the text as follows: 

 

(i) We have added some clarification in the first paragraph on p. 11 regarding 

the additional states of double field theory once the latter is taken to be 

"weakly constrained". In this case double field theory encodes, in addition to 

the familiar massless states, massive momentum and winding modes, 

which are implicitly encoded in the dependence of the "massless" fields 

in the doubled internal coordinates. 

 

(ii) We agree that the E-H action to linearized order is quadratic and hence 

polynomial in fields, but what we are referring to here is the complete expansion 

of the E-H action, including cubic and all higher orders, in which case the action 

is non-polynomial. We hope that the reference to "perturbative QFT" in that 

paragraph makes this clear. 

 

(iii) We have changed and expanded the last sentence of the first paragraph 

on p. 11 in order to say in more detail what the results of Hull and Zwiebach were 

and in which case an a problem is solved that was open before. 

 

Reviewer 2 Report

Comments and Suggestions for Authors

The essay deals with a provocative proposal of an equivalence of gravity with the Yang-Mills theory. The work is intriguing and well written, and I have no specific objection to the publication. I just suggest to explicitly explain the acronyms (ER, EPR, QFT,...) when they are used for the first time. 

Author Response

We thank the referee for the positive remarks, and we agree that an 

explanation of acronyms is warranted, which we have done in the 

updated version.