Equilibrium configurations of two charged masses in General Relativity

An asymptotically flat static solution of Einstein-Maxwell equations which describes the field of two non-extreme Reissner - Nordstr\"om sources in equilibrium is presented. It is expressed in terms of physical parameters of the sources (their masses, charges and separating distance). Very simple analytical forms were found for the solution as well as for the equilibrium condition which guarantees the absence of any struts on the symmetry axis. This condition shows that the equilibrium is not possible for two black holes or for two naked singularities. However, in the case when one of the sources is a black hole and another one is a naked singularity, the equilibrium is possible at some distance separating the sources. It is interesting that for appropriately chosen parameters even a Schwarzschild black hole together with a naked singularity can be "suspended" freely in the superposition of their fields.Comment: 4 pages; accepted for publication in Phys. Rev.

Researcher positionality in cross-cultural and sensitive research

The status of the insider and outsider is an important concept for cross-cultural and sensitive research. In recent years, the concept of placement of the researcher has received much attention. Until a few generations ago, researchers who shared the same cultural, social, and linguistic background with those of the research participants mainly conducted research. However, over the last two decades, we have started to witness researchers who have different characteristics to that of the research participants conduct research in health and social sciences. In current times, this has led to the debates of insider versus outsider status of the researchers, as the way research participants “place” the researchers, and vice versa, is vital for the success of any research. In this chapter, we shall introduce the concept of researcher positionality. We will look at the debates on researcher positionality in cross-cultural and sensitive research and discuss “placing” issues such as gender, age, culture and ethnicity, social class, and shared experiences

Fundamental cosmological observations and data interpretation

ISBN 978364200791