At first I was inclined to name this post “Being precise about time,” but that was misleading. I don’t plan to talk about nano- and attoseconds. I want to talk about using the correct words when you write about time.
Perhaps, at work, you reply to a request with something like
I’ll get back to you on that real fast.
Better for you to say that you’ll get back to the person real soon. (Yes, purists, it should be really soon, not real soon).
Soon is the measure of how long it takes to reach a goal, the time between now and when the event you’re thinking about happens. Presumably not far into the future.
Fast refers to the speed at which you do something. If you get back to someone fast, you are, perhaps, in danger of colliding with someone in the hallway. You can say that a fast typist can finish typing a document sooner than a slow typist can if they start at the same time.
I once knew a mechanic who worked on cars used in drag racing (Craig Stiebeling, are you out there?). I learned from him that quick and fast have specialized meanings for drag racers:
Quick refers to how long it takes to get from the start to the finish line, and fast is your rate of speed when you cross the finish line.
Then there’s urgency—a measure of how much pressure you’re under to work quickly to finish your task soon.