Free Time!

So we finally did it! We have declared our temporal independence from the government and switched over to free time! Now the clocks in our home are all set to local mean time instead of the officially sanctioned government time for our area. The difference between our local mean time and government time is about an hour and a half: a pretty noticeable offset. But we just figure that all our appointments occur ninety minutes earlier than we used to think of them as occurring and it works out fine.

One of the best things about the switch was tonight at sunset. As you know, we're just about at the equinox, when the night is as long as the day all around the world. As you would expect, midday on the equinox would be six hours after sunrise and six hours before sunset for the twelve-hour day. And what do you know? At six o'clock tonight, the sun was setting! It felt so natural and wholesome.

Of course, local mean time isn't the same as real time. Real time varies over the course of the year. In some seasons, the days are more than 24 hours long while in other seasons they're less than 24 hours long. It's because the earth, like any satellite, doesn't orbit the sun at a constant speed. But at most, we're only 17 minutes off of real time at any given point of the year, which is a good sight better than an hour and a half off.

We decided to switch to local time when we both got kind of upset about the early onset of Daylight Saving Time this year. It just felt really wrong. I mean, here we are still in winter and the government is shoving us into a summer time schedule. So we decided to reject the oppression and forge into a new frontier! And it feels good.

If you want to switch to local mean time, too, it's pretty easy. The easiest way is to calculate the difference between your local mean time and Greenwich mean time, which is the local mean time at the prime meridian (longitude zero degrees).

To do that, first find your longitude. You could use a GPS device if you have one handy: that's what we did. An alternative would be to look up your hometown on Wikipedia. Say you live in Punxsutawney, Pennsylvania. Go to Wikipedia's page for that city and notice the page title with a horizontal line right under it. Under the horizontal line, you'll see on the left a statement like "From Wikipedia, the free encyclopedia". On the right, you'll see the coordinates for the bustling metropolis of Punxsutawney (right over the photo of the Groundhog Day celebration in the case of this particular city). Notice that the longitude of Punxsutawney is listed as -78.975175 (you know that one's the longitude because longitude is parallel to the y-axis on a typical Mercator map, and the y-coordinate is always listed second).

Once you've got your longitude, divide it by 360 and multiply the quotient by 24. This gives you the difference, in hours, between Greenwich mean time and your own local mean time. So in the case of Punxsutawney, -78.975175 divided by 360 is -0.219375486111111. . . . Multiply that by 24, and you get -5.26501166666. . . hours (or -5 hours, 15 minutes, 54 seconds) off of Greenwich mean time for Punxsutawney mean time.

Now that you know the difference between Greenwich mean time and your own local mean time, all you need to do is set your clock that far off of Greenwich mean time. To do that, you need to know what Greenwich mean time is. Here is the website we used to find Greenwich mean time. You can also get it here or here. Now you just add the difference you found in the previous step to Greenwich mean time and you get the local mean time for your area. For Punxsutawney, then, you'd subtract 5 hours, 15 minutes, 54 seconds from Greenwich mean time and set your clock to that (remember that adding a negative number is the same as subtracting a positive number).

For the western hemisphere, I find it helps to set your clock right at noon. If I were in Punxsutawney, I'd go to my computer some time near midday and get to a website that told me Greenwich mean time. Meanwhile, I'd set my computer clock to noon even and wait before clicking 'Apply' or 'OK'. As soon as Greenwich mean time hit 5:15:54 pm, I'd click 'Apply' and set my computer's time to noon, exactly 5 hours, 15 minutes, and 54 seconds behind Greenwich mean time. Then I'd set a watch or small, portable clock to match my computer's time, and I would then take that watch to every clock in my house to set each one to Punxsutawney mean time.

Of course, you can also calculate local mean time yourself by observing the local real time. To do that, just find the time when the sun is highest in the sky (which you can do with a stick stuck straight into the ground and see when the shadow is shortest and/or when it points due north or due south) and then use the equation of time to calculate local mean time based on the observation.

If you decide to join us in using your own local mean time, then enjoy the free time!