Working on my final thesis draft has me thinking about time-scales. From our point-of-view time is linear, marching at a constant rate from past to future (unless you are stuck in an extremely dull lecture or on an overcrowded bus crammed beside someone with bad BO – then time seems to slow down to a snail's pace). So, when the conditions are right for something to happen, how long until it does? This isn't so easy to figure out, however, it's relatively easy to figure out the minimum time when that 'something' can happen. For example, my favorite, and apparently everyone else's favorite, coffee goes massively on sale once in a while. When I see the sale in the flier, the conditions are right for cheap coffee. However, I'm at home and the coffee is a short walk away. So, even though the conditions are right, the minimum time I can actually get the coffee is about 15 min later (I've learned this cheap coffee sells out quickly, so I need to go right away). So the coffee time-scale is about 15 min – which is the minimum amount of time until I have the coffee.