Tribute to H. Eugene Stanley.

T issue of the Journal of Physical Chemistry B is dedicated to H. Eugene (Gene) Stanley, William Fairfield Warren Distinguished Professor and Professor of Physics, Chemistry, Biomedical Engineering, and Physiology at Boston University. The scope of Gene Stanley’s research accomplishments is virtually unparalleled in the physical sciences. In more than 1000 publications, he has made groundbreaking contributions to the fundamental understanding of phase transitions, critical phenomena, polymers, biological materials, protein aggregation, the statistics of DNA sequences, econophysics, granular materials, physical and social networks, and especially supercooled and glassy water. With nearly 48,000 citations to his journal articles (109 of them with more than 109 citations) and over 8000 citations to his books, Gene’s work has had enormous impact across many fields of science. Gene’s contributions in condensed matter theory include his important early work on the two-dimensional Heisenberg ferromagnet and the spherical model, as well as subsequent fundamental studies of percolation and dendritic crystal growth. He has fruitfully applied scaling concepts that underlie the theory of critical phenomena to biology, discovering long-range correlations in noncoding nucleotide sequences in DNA and longranged anticorrelations in sequences of human heartbeats; to economic systems, showing that the dynamics of the Standard & Poor’s 500 economic indicator can be described as a L evy stable process; and to medicine, demonstrating scaling behavior in the size distribution of neuropathological lesions in Alzheimer disease. His work on networks, both physical and social, has led to deep insights on topics ranging from the web of human sexual contacts to urban growth patterns and from the general scaling properties of networks to the catastrophic failure of power grids. Along with a select group of scientists including Austen Angell, Osamu Mishima, and the late Erwin Mayer, Gene has helped to define the boundaries of contemporary knowledge onmetastable water at low temperatures. In more than three decades of pioneering work, he has been the originator of the picture of water as a transient gel, and of the liquid liquid phase transition hypothesis for the phase behavior of cold, metastable water. Because of water’s unique importance, this body of work has farreaching implications in biology, astrophysics, materials science, and the technology of low-temperature preservation of biological molecules. In 1979, Gene proposed a model that has had lasting impact on the understanding of supercooled water. In this model, correlations between density, energy, and entropy fluctuations arising from the formation of hydrogen bonds give rise, at low temperatures, to anomalous increases in the response functions, such as those observed experimentally in supercooled water. This model, which was subsequently discussed in detail in a now-classic paper with Jos e Teixeira, provided the first molecular-based interpretation of the anomalous properties of supercooled water (sharp increase of response functions upon cooling), which had been discovered by Angell and co-workers a few years before. For more than a decade, the Stanley Teixeira correlated site percolation model, together with Speedy’s stabilitylimit conjecture set the terms of the debate on the interpretation of supercooled water’s thermodynamic behavior. In a series of highly influential papers beginning in 1992, Gene and his co-workers proposed the fascinating hypothesis that, at sufficiently low temperatures, pure water phase-separates into two distinct forms. According to the liquid liquid phase transition hypothesis, the two low-temperature phases are the liquid analogues of the two experimentally observed distinct glassy phases of water, known as LDA (low-density amorphous ice) and HDA (high-density amorphous ice). Two papers from among this body of work deserve special mention: the 1992 molecular dynamics study of supercooled and glassy water, where the liquid liquid transition hypothesis was first formulated, and the 1998 paper with Mishima, which, in a veritable experimental tour de force (measuring the metastable melting curve of a high-pressure polymorph of ice), provided evidence consistent with the liquid liquid transition hypothesis. The liquid liquid phase transition hypothesis remains a subject of active inquiry and vigorous debate. In addition to providing a plausible (but not proved) interpretation of experimental observations on supercooled and glassy water, it has also opened up an entirely new field of research, which has come to be