A Coherent Electrodynamics Theory of Liquid Water

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript proposes a theoretical framework based on quantum electrodynamics (QED) to explain the anomalous behavior of liquid water. The theory postulates that water is composed of two coexisting phases: a coherent phase, where molecules form phase-locked coherence domains (CDs), and an incoherent phase that behaves as a dense van der Waals fluid. By solving polynomial-type equations, key thermodynamic properties such as minima in the isobaric heat capacity per particle (IHCP) and isothermal compressibility, as well as the observed divergent behavior near 228 K, are derived. The theory also explains water's high static dielectric constant.

Most importantly, the authors present a unified explanation of water anomalies from the first principles of QED, integrating quantum coherence with macroscopic thermodynamics. This approach differs from previous phenomenological models by providing a fundamental basis for understanding the structure, dynamics, and thermodynamic properties of water. The theoretical framework has significant implications for biological systems, materials science, and fundamental physics. Future work is planned to extend the theory to phase transitions, interactions with solutes, and the freezing process.

Overall, the paper is well-written. The title accurately reflects the content. The abstract provides context, presents the research objective, reports some relevant results, and presents well-defined conclusions. The introduction contextualizes the manuscript's topic, clearly presents the knowledge gap, and highlights the importance of the research. The methodology section ("2. Part I")) is quite clear regarding the theoretical approach and equations used, which constitutes the basis for replicability in a theoretical study. The results are clear and well-presented. Likewise, the analysis of the results is sound and well-founded, despite the acknowledged limitations of the model. Finally, the conclusions are entirely consistent with the study's objective.

Below are some minor suggestions

1. In the abstract and page 14 "There is a slight inconsistency in the temperature notation, using "228K" and then "228 K". It is a minor inconsistency but worth making uniform." 228 K
2. Figure 7 and Figure 9 are the same, you must ensure that all references in the text point to the correct figure (Figure 7 in this case).
3. In sections 2.3 and 2.4, the vibrational contributions to the free energy and heat capacity are mentioned. A brief explanation of why "only the low-energy modes (with ℏω≤100 meV) are thermodynamically relevant at room temperature" might be useful for readers less familiar with this detail, since the manuscript may be of general interest and could be consulted by a significant number of young researchers.
4. Although "implications for biological systems" are mentioned, the discussion could be expanded slightly to offer concrete examples of how this theory could change or improve the understanding of biological phenomena related to water. The classic example is protein folding.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Owing the complex and sometimes anomalous behavior of water, in this research authors developed a theory based rigorously in the first principles of quantum electrodynamics (QED). In this way, the proposed theoretical framework enables to address the fundamental question: is water a homogeneous or an inhomogeneous fluid? A subject that has been studied during more than a century involving mainly experimental results and phenomenological approaches. 

In this manuscript is proposed that liquid water is composed by two different mixed fractions, namely: a coherent phase where molecules are phase-locked over an extended space-time region (exhibiting low density) and a incoherent phase made up of individual molecules forming a dense incoherent fluid.

Thus, proposed theory challenges the conventional view that hydrogen bonding serves as the 
fundamental explanation for the behavior of liquid water as widely reported in the literature by physical chemists and chemical physicists. However, in the proposed QED-based framework, hydrogen bonds are understood to result from the deformation of electronic distributions in coherent molecular domains. Furthermore, the disappearance of hydrogen bonding at elevated temperatures is consistent with indicated theoretical predictions: as temperature rises, the proportion of coherent molecules diminishes, leading to the weakening and eventual disappearance of hydrogen bonding. 

Results demonstrated that the anomalous properties of liquid water arise from its dual character, that is, a quantum-coherent system coexisting with quantum thermal fluctuations. 

In my opinion the proposed model contributes to clarifying this interesting old academic issue important form theoretical and practical points of view considering that water is the key factor for life. Thus, the manuscript could be accepted as it is.

 

Author Response

No revisions needed

Reviewer 3 Report

Comments and Suggestions for Authors

This is a bold and ambitious manuscript that seeks to explain water’s well-known anomalies (density maximum, Cp minimum, compressibility minimum, dielectric constant, etc.) within a quantum electrodynamics (QED)-based framework. The authors develop a two-phase model consisting of coherent domains (CDs) and an incoherent van der Waals-like fluid, derive thermodynamic properties, and compare them to experimental data.

The work is mathematically detailed and internally consistent, and it connects to the historical Preparata/Del Giudice theory as well as to the LDL/HDL debate. However, the manuscript suffers from several important weaknesses: its speculative foundations, reliance on fitted parameters, oversimplified treatment of the incoherent phase, and limited experimental validation. Overall, it is an interesting contribution but not yet convincing as a general theory of water.

Major points:

*) The QED coherent domain model remains highly controversial and not widely accepted in the water community. The paper presents it as established, without sufficiently addressing the critical counter-arguments raised in the last decades. A more balanced discussion is needed.

*) While the framework is presented as “first-principles QED,” in practice many parameters (energy gaps, Lennard-Jones terms, reference densities, etc.) are treated as free and fitted to experimental data. This undermines predictive power and blurs the line with phenomenological models. Please frankly state the limitations induced by parametrizations.

*) Recent literature proved that external electric fields can enlarge the "coherence domain": Nat. Commun. 15, 1856 (2024).

*) Approximating the incoherent phase as a van der Waals liquid is too crude, especially when compressibility and Cp are central results. State-of-the-art simulations (e.g., MB-pol, TIP4P/2005) reproduce anomalies without such simplifications. A deeper comparison with these models would strengthen the paper.

*) The evidence for coherence domains of ~30–50 nm radius is indirect and not universally accepted. The manuscript relies on older claims without presenting new or decisive experimental support. A critical review of opposing experimental findings is missing.

*) The paper does not adequately compare its predictions with the widely accepted two-structure (LDL/HDL) model supported by scattering and spectroscopy. Without a head-to-head comparison, the QED model’s added value is unclear.

Minor points:

*) The narrative style is often advocative; more cautious and balanced language would be advisable.

*) Figures: some graphs (e.g., density, compressibility) show only qualitative agreement: this should be acknowledged more clearly in the captions.

*) References: additional citations to modern experimental and simulation studies (e.g., Nilsson/Pettersson 2011-2023, Skinner, Gallo, Sciortino) are necessary to situate the work in context.

*) The dielectric constant derivation is lengthy and partially speculative; simplifying or moving parts to Supplementary Information would help readability.

 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

The Authors made a very thorough revision. I recommend publication of the article but advise the authors that in the current for the newly cited articles are not included in the bibliography. 

Author Response

In the revised paper we added 21 new references mainly within the Introduction and Discussion  sections to situate the work in a context. We checked that all the cited paper are included in the references.