In the last couple of weeks I produced an article on Mass and Energy (along with a bit on Momentum). But I warned you in that article not to confuse “Mass” (which is somewhat related to Energy, after Einstein’s work) and “Matter” (which is not related to energy, despite the fact that the phrase “matter and energy” can be found all over the place.)
I’ve just finished a new article “Matter and Energy: A False Dichotomy”. This article points out that “matter” is defined differently in different contexts. And in each of those contexts, matter and energy aren’t opposites, partners, or in any other way crisply related. The situation is inherently confusing — but I hope the article itself cuts through some of that confusion and helps clear up the matter.