Differential equations are fundamental tools in physics: they are used to describe phenomena ranging from fluid dynamics to general relativity. But when these equations become stiff (i.e. they involve ...

Lateral-thinking puzzles fall into the latter category. Among the trickiest riddles out there, these brain games will give your noggin a serious workout. That’s because they’re not as clear-cut as ...

So craft one, in clear language, about your problem. Write about why the change is needed, how things will shift and what you ...