The program “Ether space-time & cosmology” to which this book belongs, comprises several volumes designed to inform the physics community of the resurgence of the ether in modern science. The reality of the concept and its importance were evident by the end of the 20th century, and at the beginning of the 21st century: researches undertaken during the last 20 years have confirmed the existence of physical properties within space, even where it is devoid of ordinary matter. In addition to the well known properties of permittivity, permeability and the ability to transmit electromagnetic waves, other features have been more recently associated with the concept of space. These include the Casimir Effect and a significant amount of energy. The necessity of the ether is not questioned today, even by those who pretend to do so, but who don’t hesitate to attribute qualities to the vacuum. Ether theory plays a creative role even if given different names such as physical vacuum, fundamental plenum or cosmic substratum. This second volume, as the first did, presents articles written by experienced physicists dealing with different aspects of the ether concept. One of the objectives of this series of books is to progressively disclose its properties. The introduction of the ether as a main actor in physical processes, will resolve a number of paradoxes in 20th century physics which arose because of its dismissal. Ether space-time & cosmology” is a development of the Physical Interpretations of Relativity Theory conferences, which began in 1988, in London, and which now take place in London, Moscow, Calcutta and Budapest. Details of these conferences, including names and addresses of contacts and sponsors, are given on the PIRT web site www.physicsfoundations.org.