BSc in pure mathematics (1984). Retired from a career in Information Technology in 2014. I divide my time between studying physics when I'm home in London and mountaineering.
Favourite area of physics is Quantum Mechanics.
Introduction This Insight looks at the various probabilistic factors and related terminology involved in disease and virus testing. As we all know, tests are rarely 100% reliable. The frequency of false positives and false negatives, however, not only depend on the tests themselves but also on the prevalence of the disease or virus within the…
Introduction A frequent concern among students is how to carry out higher order partial derivatives where a change of variables and the chain rule are involved. There is often uncertainty about exactly what the “rules” are. This tutorial aims to clarify how the higher-order partial derivatives are formed in this case. Note that in general…
Baryon Introduction At the beginning of the 20th century, it was thought that all matter consisted of only three particles: the electron, the neutron, and the proton. The major outstanding question was how the neutrons held the positively charged protons together within the atomic nucleus. In the search to answer that question, however, it was…
Introduction There are a number of posts on PF involving a general confusion over the multi-variable chain rule. The problem is often caused by a lack of clarity about the roles of functions and variables and what precisely each derivative means. This insight is an attempt to clarify things. Part A: The Single-Variable Chain Rule…