Saturday, January 18, 2014

Does Anybody Really Know What Time it Is?

When we last spoke, we discussed the use of our time, and why using it to make money in Second Life isn't generally a great idea.

But speaking about time, there's a lot of confusion about time in Second Life, and I'd like to talk about that today.  There are two basic causes of this confusion:  clock time (time zones), and sidereal (sun) time.

Time Zones
The real world is divided up into a number of time zones.  By an arbitrary historical convention, the "home" time zone for the world is located at the longitude of Greenwich, England, the so-called "prime meridian".  All time zones are referenced to Greenwich Mean Time (GMT).  Locations to the west of Greenwich are earlier in the day.  For example, New York City is five hours behind GMT, or "GMT-5"  When it's noon in Merrie England, it's only 7:00 a.m. in the Big Apple.  Similarly, locations to the east of Greenwich are in "GMT+" time zones.

"GMT" is actually an older term.  The current, politically correct term is "Universal Time" or UTC, but I'm old fashioned in some ways.  I still think of Pluto as a planet!

By the way, for the rest of this piece, I'm going to switch to 24 hour time, or "military time", to remove any confusion about a.m. or p.m.  The 24 hour clock is easy, fast, convenient and much cleaner all around.  In this naming system, midnight is 0000, and the hours of the day are numbered consecutively, using four digits and no colons separating the minutes.  2:30 a.m. becomes 0230 hours.  Lunchtime is 1200, and quitting time is 1700, not 5:00 p.m.  Dinner is at 1830 and the kids have to be in bed by 2200.  Got it, Lieutenant?  Good!

To complicate matters, some time zones change by government decree.  Some of the border lines don't follow simple lines of longitude, but meander to include some country, state, or district in one time zone instead of another.  And some of the time zones vary with the seasons, like Daylight Savings Time in the United States.  There are places you can go on the web to find out what time it is anywhere in the world.

Second Life has residents from all over the world.  You might be in world, talking to a friend from Japan.  If you are in New York City, and it's 1530 on Saturday, January 18 for you, for your friend Kimiko, it's SUNDAY, January 19, 0530.  (The date change comes because Tokyo and New York are on opposite sides of the International Date Line, the longitude directly opposite Greenwich, where the time is 12 hours different from GMT.  New York is GMT-5, and Tokyo is GMT+9, a difference of 14 Tokyo is in "tomorrow", compared with New York.)

In the Real World, we try to minimize this confusion by using GMT as a standard time.  Scientists and space travelers all use GMT.

In Second Life, we do much the same thing...but we use Second Life Time, or SLT.  All in world events are listed by their SLT.  This time is also shown in your viewer, in the upper right corner...but instead of "SLT", it's labeled either "PST" (Pacific Standard Time) or in the summer, "PDT" (Pacific Daylight Time.)  Linden Lab is located in San Francisco, California, and runs on Pacific Time...and therefore, so does Second Life!

That's pretty easy to understand, once you get used to it.  What's REALLY confusing, at least to me, are the time stamps shown in your communications window.  The time stamps shown next to lines of chat or IM are in SLT, but if you get a message while you are offline, the notification uses your LOCAL time!  This has never made any sense at all to me, and rather than try to convert such notifications, I generally just ignore the time stamps.

So much for clock time!  SLT = California Time, and everything is good.  What's that?  Oh, you say it's 0600 SLT, but the sun is just now setting in SL?  Well, that happens a Second Life, the sidereal time -- the sun position -- bears no relation to the clock on the wall (except of course, where it does!)  We'll talk more about that next time!

Meanwhile...have a nice day! 


  1. Going all pedantic here:
    Actually, scientists use UTC, which is not simply a politically correct term for GMT.
    GTM is astronomically defined, which means that two seconds may not be the same length of time, depending on how the Earth happens to rotate and hurtle through space, and Earth's rotation is gradually slowing, making the seconds longer.

    UTC is defined so each second is the same period of time, which is very convenient for precise measurements, but in turn requires "leap seconds" every now and then to keep it in sync with the astronomical GMT (and ultimately the actual day/night cycle).

  2. Hello Lindal,

    I enjoy your blog and have particularly liked these recent pieces on approaches to time and land.

    The time thing is a favorite issue of mine and I do believe it is past time or high time :) we did something to put all of us on the same page as to what time it is in virtual worlds. This has become a bigger issue in the past year especially as "grid hopping" from one virtual world to another is growing in OpenSim via the Hypergrid. And when different grids use different time zones, one can easily be confused as to exactly when a concert or dance is taking place, for example.

    I blogged about this last year and suggested a solution: We select a time zone and a name for it and every virtual world uses it. I suggested we use the Pacific Time Zone of the U.S. because it is Second Life Time and SLT is as close as we have to a standard time in virtual worlds already. I also suggested that rather than have it named after a particular world, we call it: Virtual Time or Virtual World Time. "The singer or DJ goes on at 10 VT or 10 VWT." It might sound a little strange right now but I think we'd get used to it quickly.

    My reasoning for these suggestions are spelled out in my blog. I think you might find it interesting and possibly even entertaining...

    Keep up the good work.

    Best regards,

    Danko Whitfield

    1. Thank you for the thoughtful comment! Even though I'm in the USA, and I'm used to using Pacific time for SL, I would vote for GMT to be the universal time zone for virtual worlds. Color me stodgy, but that's what everyone else uses when they want a reference time!