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Wales, United Kingdom
In autumn 2010, my husband Ian and I both quit our jobs, sold our house and left the flatlands of the east for the mountains of Wales. Our goal is to create a more self-sufficient lifestyle in a place we actually like living. Whilst Ian will continue to earn some money as a freelancer, my part of the project is to reduce how much we spend by growing and making as much of what we need as possible. The purpose of this blog is to keep friends updated with how the grand project is progressing, but all are welcome here. If you're not a friend already, well perhaps you might become one.

Sunday, 27 March 2016

About time

This morning (or yesterday evening, for the organised), clocks across Britain were set forward one hour. This is something that has always irritated me. Why do we need to do this? If we want to make the most of light mornings, why can't we just get up earlier? Why do we need to fool ourselves into thinking that the time is an hour later than it really is?

Here's the thing that irritates me: British Summer Time is not real. The position of the hands on a clock face are a measurement, and as such, should aim to measure as accurately as possible. But what are they measuring, exactly? Well... it gets a little more complicated than you might expect when you try to answer this question. Roughly, it's the position of the sun in the sky, but not relying on actually being able to see the sun, and extended through the hours of darkness, too. It's a measure of the Earth's rotation. As such, Noon should mean the time when the sun reaches its highest elevation in the sky.

There are two things which make this an approximation. The first is the use of time zones. Here on the west coast of Wales, the sun sets fifteen minutes later than it does in London and similarly, noon - meaning the highest elevation of the sun - is fifteen minutes later as well. It used to be the case that every town operated to its own local time, but the coming of the railways made it necessary to keep the same time across the whole country. Imagine trying to devise a train timetable with a different time zone for each stop!

I can see the sense in having the same time across the country, so the time is accurate to within about half an hour. For that purpose we all use Greenwich time (the political choice of a location right at the east of the country is also a little irritating - somewhere in the middle would be better), but what about the mean part of GMT? This is mean in the sense of average and derives from the fact that noon-to-noon is not exactly 24 hours, most of the time. On some days it takes a little more and on other days a little less than 24 hours for the sun to return to its highest elevation in the sky.

The reason for this variation is the eliptical shape of the Earth's orbit around the Sun. I was going to give you a brief explanation there, but then I looked it up and it got complicated. If you're interested, Wikepedia has a lengthy article on the subject. The upshot is that some of the time, a sundial is fast relative to a clock, and some of the time it is slow. When clocks were new, the sundial was taken to be correct and an adjustment was applied to the new-fangled clocks to calculate the correct, sundial time. Nowadays, if you are so inclined, you can apply the adjustment (in reverse) to sundial-time to get the correct time as per a clock.

This leaves me in a quandry. I share the modern instinct that the regular clock, with exactly 24 hours each day, is the more correct measure of passing time, but if the sundial, which reliably reports the position of the sun, is inaccurate, what are we measuring with the clock? The concept time of day has become abstracted away from the position of the sun, and that abstraction opens the door to people mucking around with it, with time zones and daylight saving. This feels wrong, as if we've somehow become separated from a fundamental aspect of the natural world. I am very tempted to set up a sundial in my garden and use only that for timekeeping. If only we had more sunlight.

2 comments:

  1. Oh my! Apparently this time of year promotes discussions on these sorts of topics. CatMan and I had a lengthy discussion on Gregorian vs. Julian calendars and lunar vs. solar calendars - all brought on by the curious fact that Easter is almost an entire month before Passover this year!

    Anyhow, I actually LOVE daylight saving time, and wish we could just stay on it year round - but it's at least partially because Denver sits in the eastern part of the Mountain Time Zone, so our sunsets are much earlier than I think they should be. Being a night owl also contributes to my preference for DST because I see morning light as "wasted" since I'm generally asleep when it happens.

    CatMan always says I could just get up earlier if I wanted to - and this is, of course, true - but I can't make the evening news come on earlier, or make evening events happen earlier, yadda, yadda, yadda.

    I do have a fantasy of being able to completely discard all of my clocks one day - this goes along with my fantasy of getting rid of lights and televisions and computers - of course, that would require a great deal of weaning from the culture in which I live, which I'm not quite ready to do yet. But maybe someday... It would certainly be the more natural approach!

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    Replies
    1. I hope you'll forgive me for sticking my oar in here, because I know this is a subject you've given a lot of thought to, but I got thinking...

      I was wondering whether daylight saving time is just an hour closer to your natural waking/sleeping time, then realized that I'm waking up later 'by the clock' at the moment because I haven't adjusted yet, so daylight saving goes against night owls if you don't shift your sleep hours.

      That must mean that you love daylight saving because it forces you to shift your sleep an hour earlier, in which case, your sleeping times are responsive to external cues, such as the time on the clock, the evening news, other evening events, yadda, yadda, yadda.

      If your sleep patterns are (at least partially) responsive to external cues, I'm puzzled by a couple of things: I'd have thought sunlight would affects you, being quite a strong external cue. If it's social cues you respond to, like evening events, how come you end up with sleep patterns that are out of sync with other people?

      It's as if you have a deep, subconscious belief that the time to go to sleep is x hours after everyone else goes to sleep, and that belief is massively resistant, even to things like daylight saving.

      Hmm, not sure what that does for you, but that's my two penn'orth, anyway.

      Delete

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