I noticed that the subject says "decimal time," which is not what I'm talking about. I'm talking about the use of currently defined SI units.
> I'm not sure what your point is, here. I wasn't arguing for conversion to > metric units. Using metric units is a given on this list server, with no > argument in favor being necessary. Excuse me, but I thought that was the whole POINT of this list! Is it not for promoting the conversion to metric units in the US? And in order to do so, are not arguments in favor necessary? Or is this list merely a circle-jerk? I am a metric advocate. I posted here because recently I had a discussion with a guy from Sweden who is proposing that the entire metric system be changed so that the base unit of time interval would be 1/1,000,000 day, and all SI units derived from the second be replaced. (Although I have long been intrigued by the use of decimal time of day, such as Julian Dates and French revolutionary time, I get annoyed by all these people who claim to have invented "metric time" (which usually has little to do with the metric system beyond being decimal) who seem to be ignorant of the fact that there is already a metric unit of time, and who cannot distinguish the difference between time interval and time of day.) I have argued that such a change is unnecessary, impractical and prohibitively expensive. However, my arguments are undercut by the continued use of non-metric units with regard to time interval. We know "how many hours it is to the destination" because we know hours. I was tought how to tell time in scool, in hours and minutes. I was also taught the metric system, pretty much once a year then forget it. (I don't recall any such comprehensive instruction on customary units of measure, which is probably why I still don't remember how many pints are in a gallon, etc.) I don't remember ever hearing any mention made of kiloseconds, nor of hectoseconds, dekaseconds, etc. If people were taught to think in terms of ks, then there would be no need for km/h. I don't see how this cannot be done part and parcel with teaching the rest of the metric system. It would not require a change in telling the time of day, merely of units of time interval. If people were familiar with ks as a unit of time, then they would not have a problem with travel speeds given in m/s, since they would know that this is the same as km/ks, and know how many km and how many ks. The only reason that we do not know this now (how many ks to the destination) is because we don't know ks. We could learn to use ks, and Ms, etc., along with derived units such as m/s, without changing the way we tell time. But I am not trying to convert anyone, merely asking a question, why do we still use non-metric hours and minutes but NEVER kiloseconds? I am not advocating that kiloseconds replace hours and minutes for determining the time of day. That has not even occurred to me before. I don't think that would be practical or desireable, nor would it be necessary in order to use ks. However, on a lark I just now created a JavaScript clock that counts ks from 00.000 to 86.399, which you can view at http://john.hynes.net/ks.html. I don't expect anyone, including myself, to use it; it's merely for amusement. It may or may not be a good idea to use decimal time of day (as the French tried while they were creating the first metric system) but this is an entirely different subject from metric time, i.e. metric units of time interval. John Hynes ----- Original Message ----- From: "Bill Potts" <[EMAIL PROTECTED]> To: "U.S. Metric Association" <[EMAIL PROTECTED]> Sent: Tuesday, December 07, 2004 11:06 PM Subject: [USMA:31621] RE: Some decimal time... jabs > Responses interspersed. > > >I used km/ks as a comparison with km/h, keeping the top unit the same, > >instead of 27800 km/s. > > That's somewhat fast. In fact it's almost one tenth of the speed of light. > Gotta watch that decimal point. > > >The problem with your explanation is that you say it "makes sense" to use > >hours only because "you know" hours. You could just as well say that it > >makes sense to use miles because you know how many miles it is. > > I didn't say anything about knowing hours. I referred to knowing how many > hours it is to the destination. > > >That is not a good argument for not converting to metric units. Most > Americans would > >not be able to easily calculate their travel time from km/h, because they > >use miles, but does that mean that they should continue to use mph? > > I'm not sure what your point is, here. I wasn't arguing for conversion to > metric units. Using metric units is a given on this list server, with no > argument in favor being necessary. > > Americans would, in fact, find it just as easy (exactly as easy, in fact) to > calculate travel time from their speed in km/h as they do now from their > speed in mph. That is, assuming they know how many kilometers it is to their > destination. > > The whole point of conversion (metrication) is getting people used to > thinking > >metric. They should be able to wrap their minds around m/s just as you > >expect them to switch from miles to kilometers, if they get used to using > >kiloseconds, as well. > > The 95% of the world that uses metric almost exclusively has its collective > mind wrapped around km/h, not m/s, for travel. > > Meters per second make a lot of sense for wind speed. You can visualize the > leaves blowing down the road at 10 m/s, for example. The speed with which a > baseball pitcher throws the ball lends itself perfectly to m/s. An analysis > of a collision between two cars should almost certainly involve an estimate > of the closing speed in m/s. One could cite examples ad nauseam. > > >I'm aware that the hour is accepted for use with SI, but it is still not a > >metric unit. It is not a multiple formed by adding a prefix to the base > >unit of time interval, nor is it a derived unit. And it is not just the > >common people who use these "accepted" units, i.e. minutes, hours and days. > >These units are used by scientists, as well, instead of kiloseconds, etc. > > Whether they are used by scientists depends on which field of science is > involved and to whom the scientists are talking. Among themselves, they may > very well say that the Universe is about 7.9 Ps (petaseconds) old. In > communicating with non-scientists, they are more likely to say 15 billion > years. Their audience thinks in terms of birthdays, new year celebrations, > anniversaries, historical dates, etc. Do you prefer to talk about the War of > 1812 or would you prefer to date it by the age of the Universe, in > petaseconds, at the time it happened? (I'm taking some liberties in citing > that as an example, as the age of the Universe is only an estimate.) > > It just seems ironic to me that we aren't considering kiloseconds > >along with the rest of the metric system. > > That may be because we have several billion clocks, watches and other > timekeeping devices. We also have billions of historical documents in which > the time was recorded in the same manner as today. The 24/60/60 scheme is > far more entrenched than Imperial or U.S. Customary ever was. > > The day is based on a natural interval > >(although the SI day is defined as being exactly 86400 SI seconds) > >but hours > >and minutes have no basis in nature and we could probably get used to using > >kiloseconds, even though there are not a round number of them in a day. We > >could make clocks which count from 00.000 to 86.399 ks, for > >instance. Maybe > >our TV shows could be made longer or shorter to accommodate a round > >number of > >ks, maybe 2 or 4 ks instead of 30 or 60 min. > > One can be a zealot or one can be pragmatic. I think most of us who advocate > a massive shift to the metric system are pragmatic. The people at BIPM, ISO, > ASTM, IEEE, NIST, and so on, are certainly pragmatic. > > History is with us with respect to a full shift to SI as it is currently > defined -- including units accepted for use with SI (and which are quite > clearly not discouraged). History is against us with respect to the everyday > use of the kilosecond. I've learned to accept that and am content that the > best we can probably do is to encourage the use of the ISO 8601 Standard for > dates and times (yyyy-mm-dd hh:mm:ss). > > If you are still not convinced, perhaps you'd like to outline for us a > public relations and educational campaign to convert the entire world from > hours, minutes and seconds to kiloseconds and seconds. I would not consider > such an outline complete without a full accounting of the probable costs and > an estimate of the time it would take. (In doing the time estimate, you > should feel free to use megaseconds, gigaseconds, or teraseconds, as > appropriate.) > > Bill Potts, CMS > Roseville, CA > http://metric1.org [SI Navigator] > >
