When you work across many time zones, you do time arithmetic in your head, counting on your fingers and very roughly if need be. Portugal is 8 hours ahead of Portland, etc. However, when it comes to publishing the time for a meeting that can involve people from all over the world, I always use http://www.timeanddate.com/ to check the time. Also, I always write invitations with UTC (or GMT/Zulu)-time, plus New York or San Francisco just to support the intuitive side. In fact, usually I go the extra mile and provide a link to a specific time for the meeting, so people can just click to see what time it will be for them.

How very nice that tonight is the night for changing daylight saving in such a synchronous fashion! Europe and the US fall back and Australia springs forward on the same date. Would that it were always so easy. When next spring comes around, it all happens on different dates, so your short-hand calculations don’t work for the last week in March / first week in April. And a year from now the US changes at a different time, so there will be a few “gotcha weeks” when planning meetings will be more difficult and your rules of thumb won’t work. How about a little global integration for such things?

Anyway, I find that adding and subtracting time zones is hard for me, but a good rule of thumb, supported by a widget like Foxclocks, to keep my intuitive mental clock as accurate as possible, seems to work pretty well. It’s still a lot of work. This quote from Jean Lave certainly applies very much to doing time-zone arithmetic: “Activity such as arithmetic problem solving does not take place in a vacuum, but rather, in a dialectical relationship with its setting.” Change the setting and problem-solving is likely to change, too.

We’re just wrapping up the September 2006 Foundations of Communities of Practice workshop and one of the things that seems to bend the minds of so many participants is actually working intimately with people in distant time zones. Part of the magic of the workshop is that all of a sudden the hassle of working across time zones is worth the effort. The October 12th, 2006 issue of The Economist has a survey of telecoms convergence that suggests that, “even if the traditional telephone is not quite dead yet, its business model certainly is: metered telephone calls whose cost depends on the length of the call and the distance covered are becoming an anachronism.” And yet time zones persist and they are not necessarily managed in a coordinated fashion (well, at least Indiana now conforms with the rest of the US, but what about coordination with the time in Mumbai or Moscow?). More and more of us have to deal with more and more time zone calculations, thanks in part to the falling cost of a phone call (and of synchronous interaction in general) but it’s not as easy as it should be.