Entries by Orodruin

Learn the Basics of Dimensional Analysis

As a university teacher and as a PF member, I have often noted that students are largely unaware of or not using dimensional analysis to help them in their pursuit of knowledge or to check their results. A number of recent threads on PF have also highlighted this issue. This intent of this Insight is…

The Birth of a Physics Textbook

  It is said that you should accomplish three things in life: Plant a tree. Have a child. Write a book. Out of the three, I have completed at least one. At the time of writing this Insight, my textbook “Mathematical Methods for Physics and Engineering” just hit the virtual online shelves. This Insight will…

Knut Lundmark and the Prehistory of Dark Matter

Look in your standard cosmology textbook (in my case, the closest one at hand is Barbara Ryden’s Introduction to Cosmology) and go to the section which describes experimental discovery of dark matter. Two of the things you will likely find in there are the following pieces of information: The virial theorem applied to the Coma cluster by…

Plus/minus What? How to Interpret Error Bars

People some times find themselves staring at a number with a ± in it when a new physics result is presented. But what does it mean? The aim of this Insight is to give a fast overview of how physicists (and other scientist) tend to present their results in terms of statistics and measurement errors….