In spite of the seemingly complete compatibility of these outer bonding considerations with all the known and emerging properties of bulk and interfacial water, with no apparent failures, there has been much opposition to the mixture-model views expressed here. However, more recently, with the emergence of growing experimental support, mixture-models are starting to be offered by others for the understanding of water [23,24,57]. Unfortunately, these other models have so far provided a much less explicit representation of the local water structure than the model presented in our own work. Missing, for instance, is the explicit 4.5 Å to 3.5 Å transformation in the outer bonding regions of the liquid, which we believe to be central to all the anomalous properties of water. In fact, over the past twelve or so years, no clear description of the anomalies in terms of the two-state mixture-model structure has really been presented except in our own papers.

The hesitation to be more explicit about "structure" in the liquid is clearly related to prejudices within the liquid state community, even though the use of RDF data has been commonplace for a very long time. These prejudices were reinforced by Kauzmann’s early attempt [58] to discredit anything resembling a "mixture-model" for water. Kauzmann’s alternative to mixture models is summarized on the second page of his 1975 paper, "I strongly suspect that future progress in our understanding of liquid water is much more likely to come from recent approaches which begin at a more fundamental level by assuming no more than a reasonable potential function for water-water interactions, and then proceed by means of the computer or more or less rigorous statistical mechanical methods". Though these suggestions may seem reasonable, and have in fact been followed by all later workers on water, almost no progress towards the understanding of the anomalies of water was made until the reintroduction in our 1986-1987 papers [4,5] of the two-state mixture model. In fact, the stated goal in a later paper [6] was "to try to get the venerable mixture model for liquid water back onto its feet." These efforts have been decidedly uphill. Kauzmann’s influence has been so strong that other workers, until quite recently, have ignored mixture-model views. Does this reemergence of a physically understandable very simple mixture-model view about water in a number of different laboratories mean that the century-old problem of liquid and interfacial water will at last soon find a solution that is generally accepted by condensed matter physicists, chemists and biophysicists alike? One would like to think so, but only time will tell.

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