Times and Folding; Theory of Relativity

A few less-than-scientfic ponderings:

Times and Folding

Today in class the prof was talking about enzyme kinetics, and how a "hundredfold" increase in concentration covers most of the range of reaction rates. My problem is not with enzyme kinetics but rather with the use of "numberfold." I have never been sure what exactly it means. Is "fold" the same as or different than "times?" I feel as though it is commonly used as both of these.

Example: "Our profits increased twofold." Does that mean our profits doubled, that is, went up times two, or does that mean the profits were quadrupled, that is, folded two times, or two raised to the power two? When I hear "fold" I immediately want to exponentiate 2ⁿ (like folding a piece of paper n times), but it seems that it is not always taken as such.

Theory of Relativity

Not the one that good ol' Al thought up. I'm talking about relative periods of time. I notice in my writing and speech that I use relative measures of time quite often, and it can be a bit confusing for everyone because I don't always give the benchmark to which it is relative. What I ought to do is force myself to adopt a set of standards for the following cases:

1. When does the other day become last week?
2. When does several weeks (e.g. six or eight if we were talking exact terms) become a few months?
3. When does about a year and a half become about two years?
4. When does recently become a while back and then change to a long time ago?
5. What the hell do I mean when I say when I was younger???

I suppose it's all just a question of rounding and significant figures, all relativity. But it sure makes it rough when I say, "I haven't seen that movie in a long time," and then I need to clarify, "Well, I saw it about a year and a half ago," when indeed I saw it twenty months to the day!