Subject Interest Groups: physics, mathematics, theoretical physics, astrophysics This book includes important papers written by R Cahill, J G Hartnett, F Cardone, A Marrani and R Mignani, J Dunning-Davies, A Gutierrez-Rodriguez, M A Hernandez-Ruiz and J M Rivera-Juarez, A Vankov, P O'Donell, J Lopez-Bonilla et al, V Varlamov, G.-j. Ni. Interesting mathematical questions of relativity theory, relations to the modern astrophysics, as well as some conceptual foundations are considered in the papers.