In a comment on the quantitative Doppler effect post, my mother had the following to say:
"Mom again. I have a feeling that however clearly you explain it, some people who have never taken advanced math in any form will never really understand it. I like much better the idea of the dark matter, the neutrinos racing through my finger-tips, etc. Perhaps you should select your subject-matter differently - when you say you are a physicist, what questions do people at cocktail parties ask you? I'm sure not about variables. The best stuff is the underground machine etc. You may think I am trivial or superficial-minded, but I speak honestly."
I understand her point, but I think I'd like to keep trying with the quantitative posts every now and then anyway. The problem I have with separating this blog from the quantitative aspects is that without the math behind it, physics is reduced to a matter of faith. It's nice to talk about neutrinos going through fingernails and underground mines, but at a cocktail party I inevitably have to say something like, "trust me" or "you'll just have to believe me." We can't actually feel neutrinos going through our fingernails. With this blog I'm trying to show that the rather general, romantic and literally intangible idea of dark matter is actually based on years and years of physics research and that most of what goes into it is fully understood and not a matter of faith at all (although, I will be the first to admit that much of it is speculative - after all, we don't truly know what we are looking for, just that it is there).
As physics arguments are generally expressed in mathematical terms, I think I'll keep the math arguments in there from time to time, even if my mom generally ignores them. I think she could understand it if she really wanted to and it was explained well (which this blog probably will not do as it's probably the wrong vehicle anyway), but in the end, it really doesn't matter to her if she can derive an expression for the Doppler effect or not, does it? The main point that I would be trying to illustrate, then, is that such a derivation exists and could be understood.