Introduction About the author As a long-time woodworker, I enjoy being able to tell one wood from another. In the process of learning how to do that, I’ve developed some knowledge of wood anatomy that I think will interest both biology students and woodworkers. There is an enormous variety of wood-anatomy characteristics; this article discusses…
Overview of “What If” Questions We receive many “what if” questions here on Physics Forums. This article explores three common types and offers suggestions for students whose questions may fall into one of those types. “What if” questions that contradict physics as we know it. “What if” questions that are themselves self-contradictory. “What if” questions…
Computer languages fall into a small number of core types: machine language (raw binary instructions), assembly language (human-readable mnemonics for those same instructions), compiled higher-level languages (like C, Java, and Python), interpreted and scripting languages (like BASIC, JavaScript, and Perl), and markup languages (like HTML). Each trades programmer control for ease of use, with assembly…
The balloon analogy uses pennies glued to an inflating balloon to show two ideas from modern cosmology: that unbound regions of the universe expand roughly uniformly over large scales, and that this expansion has no center. The analogy is a simplified teaching tool, not a complete model of cosmology, and it breaks down if pushed…