Anything other than a single letter variable with at most subindexes, bold, upper/lower case simply doesn't work in maths and science. And because we only have 26 letters, you do have to go to Greek.

Actually, that might be a good exercise: try doing some moderately abstract equations with variable names such as you'd write in a programming language and you'll find yourself shortening them pretty quickly. We literally do it sometimes when modeling an equation for a new domain: we start by writing words and at the end of the blackboard they already became a symbol.