I think parallel universes would come in handy at times. Right now I’m setting up several meetings that involve different people from disparate settings. My usual mode is to send out an email saying “Give me your days and times and I’ll attempt to match them up using the most common denominator.” Invariably the days that suit some, others urge me to avoid at all costs. If we had access to an asynchronous parallel universe or two we could handle calendar clashes – just slide from one reality to the next!
How to keep track? Outlook already allows multiple calendars. Those who still carry appointment books could colour code them. You’d have to be extra vigilant, of course. Trying to remember which universe you absent-mindedly left your car keys in would be an extra challenge.