Science has often used the humble thought experiment, for example Schrödinger's cat, Einstein's elevator or Maxwell's demon (check them out for an interesting distraction), to think through a problem, to test a theory or to pose possible solutions. It's cheap and immediate and doesn't require a building full of equipment, just some innovative brain power and possibly a whiteboard. It can also have uses in everyday life, both private and business.
Business workshops invariably focus on outcomes, whereas thought experiments allow the mind to explore the unknown and to go down as many rabbit holes as needed, without consequences. There are no limits, other than those of imagination.
So when you see someone deep in thought and apparently doing nothing, don't disturb them. Thought precedes action and they may be thinking through the next big breakthrough … or thinking about what to do on the weekend. You may never know but give them the benefit of the doubt. I suspect that even Einstein sometimes appeared to be idle.
And for those of you who need to be busy and can't live without deadlines, a final thought from the late, great Douglas Adams: "I love deadlines. I love the whooshing noise they make as they go by.”