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Editorial: 50 years of Statistical Physics in Mexico: Development, State of the Art and Perspectives

In the autumn of 1971, the small group of physicists then working at the Instituto Mexicano del Petróleo (IMP), in Mexico City, was expecting the visit of several distinguished scientists from abroad, who had been invited for talks and seminars on various topics of Statistical Physics. The Mexican physicists at IMP realized that it was an excellent opportunity to organize a meeting on the subject; it could be held the coming January, when most of the would-be speakers were available. Nevertheless, no formal organizing committee was appointed. Leopoldo García Colín, then director of the Applied Research Division at IMP, oversaw the whole operation, made the formal invitations and secured the financial support from IMP. The meeting itself was organized by Fernando del Río, who was assisted by his then Ph.D. student, Luis Mier y Terán, and by Sigurd Larsen, who was on sabbatical stay at the Institute. Besides a fewMexican speakers who joined the visitors from abroad, the participants in thatmeeting were mostly graduate students who were working on the subject. By a combination of sheer luck and common sense, the meeting was planned to be held at Oaxtepec, a lush site about 70 km south of Mexico City that boasts a spring-like weather all year round. The meeting had no title nor name, and nobody foresaw that it would become a yearly event, nor thought to take a group photograph. Among the foreign speakers on that (first) meeting were Melville Green, Sigurd Larsen, Joel Lebowitz, Anneke Sengers, Jan V Sengers, and Robert Zwanzig. The meeting had a wide success. The talks were of the highest quality, and the ample time available and pleasant surroundings was profited by the young Mexican students, who interacted closely with the speakers. This success spurred the decision to organize a yearly event every winter. Since then, 49 meetings have been held, the last one in January 2020. This year should have seen the 50th, but it was suspended due to the Covid pandemic. The Winter Meeting on Statistical Physics (WMSP) constitute the series of physics gatherings of longest standing in Mexico, and have been a valuable asset in promoting the growth and consolidation of the discipline. In these 50 years, Statistical Physics inMexico has grown from a single site of research and a handful of practitioners to almost twenty centers around the country and hundreds of scientists. The present collection aims to commemorate the long standing tradition of the WMSP. It begins with a review of molecular-based equations of state. Regardless of how they are derived (experimental data or simulation results) when obtained from statistical mechanics; these equations are labeled molecular-based. In this work, a general scheme for the derivation of truly perturbed equations is presented. Two approaches are identified, Bottom-up and Top-down, and Edited and reviewed by: Alex Hansen, Norwegian University of Science and Technology, Norway