From: Pat Naughtin <[EMAIL PROTECTED]>
Reply-To: [EMAIL PROTECTED]
To: "U.S. Metric Association" <[email protected]>
Subject: [USMA:37820] Speed of light
Date: Sun, 21 Jan 2007 20:32:05 +1100
Dear Brij,
As you know the metre is currently defined as a fraction of the speed of
light and it has been since 1983 October 21.
This definition of the metre is based on a speed of light that is exactly
299 792 458 metres per second. This is exact because the metre is defined
by
this exact fraction.
Have you ever considered the implications that might follow if the
definition of the metre was altered slightly so that the speed of light
became a neat round number of 300 000 000 metres per second. The definition
of this new metre would then be:
'The metre is the length of the path travelled by light in vacuum during a
time interval of 1/300 000 000 of a second.'
I would appreciate your thoughts.
Cheers,
Pat Naughtin
PO Box 305 Belmont 3216
Geelong, Australia
61 3 5241 2008
Pat Naughtin is manager of http://www.metricationmatters.com an internet
website that primarily focuses on the many issues, methods and processes
that individuals, groups, companies, and nations use when upgrading to the
metric system. You can contact Pat Naughtin at
[EMAIL PROTECTED]
On 21/01/07 6:59 PM, "Brij Bhushan Vij" <[EMAIL PROTECTED]> wrote:
> Pat & all:
> BIPM & CCU have been 'in delibration' to the use of mm, cm, m & km - the
> common factor being the definition of Length Unit METRE, as a measure of
the
> distance traversed by light during 'specified time'. However, cm & mm
are
> convinient for laboratory work, BUT distance between towns need be
measured
> in km & day-today commercial activity only METRE is preferred unit of
> distance.
> Yesterday, an irrelevant question came up i.e. conversion of - say wind
> velocity 65 MPH to days, weeks, months, years etc. Yes, this sets in a
> dimension less unit *time/time - a number - like SOUND factor Unity, to
> represent velocity of sound.
> I argued to redefine length unit, METRE New (m' or yd') in terms of
> arc-distance on Eaarth surface, made by arc-angle Pi/180 (1-degree) at
> centre of Earth. I call this Metre New (m') [ or for convinience Yard
New
> (yd')]. This can easily be defined via distance traversed 'in time' at
> velocity of light. Please also see:
> http://www.brijvij.com/Brij.d-sec.sd.doc
> Regards,
> Brij Bhushan Vij
> (MJD 2454122)/630+D-021 G (Sunday, 2007 January 21 H13:54(decimal) IST
> Aa Nau Bhadra Kritvo Yantu Vishwatah -Rg Veda
> Jan:31; Feb:29; Mar:31; Apr:30; May:31; Jun:30
> Jul:30; Aug:31; Sep:30; Oct:31; Nov:30; Dec:30
> (365th day of Year is World Day)
> HOME PAGE: http://www.brijvij.com/
> ******As per Kali V-GRhymeCalendaar*****
> "Koi bhi cheshtha vayarth nahin hoti, purshaarth karne mein hai"
> Contact # 011-9818775933 (M)
> 001(201)675-8548(when in US)
>
>
>> From: Pat Naughtin <[EMAIL PROTECTED]>
>> Reply-To: [EMAIL PROTECTED]
>> To: "U.S. Metric Association" <[email protected]>
>> Subject: [USMA:37818] Re: Centimeters
>> Date: Sun, 21 Jan 2007 18:25:55 +1100
>>
>> Dear Tom,
>>
>> Thank you for your detailed commentary on the use of the centimetre.
>>
>> I have interspersed some remarks in black.
>>
>>
>> On 3/01/07 1:20 AM, "Tom Wade" <[EMAIL PROTECTED]> wrote:
>>
>>>> It seems to me that applying the adjectives 'perfectly good' to the
>>>> centimetre following such observations is inappropriate.
>>
>> My objection to the value judgements implied in the words, 'perfectly'
and
>> 'good' are simply based on my observations that metrication transition
>> processes are much, much, slower when centimetres are used rather that
>> millimetres.
>>
>> Let me clarify the basis of my personal observations. I have been
observing
>> metrication processes and attempted metric conversions closely since
1970
>> and I have yet to see any fast, smooth, or economical metric
transitions
>> that involved using centimetres. Typically, the use of the centimetre
>> simply
>> leads to a long, protracted, rough, and expensive process where metric
>> conversions dominate both TO metric units but more often FROM metric
units
>> back to the old pre-metric measures.
>>
>> However, having said that, I know the status of the centimetre both
>> historically and in the current BIPM brochure.
>>
>>> The centimeter is certainly a 'perfectly good' unit. When it comes to
>>> standardizing within an industry, the millimeter is far more likely to
>>> be the more appropriate unit, but this is not necessarily always the
>> case.
>>
>> My assessment based on Australian job titles is that millimetres are
used
>> in
>> about 84 % of trades, crafts, and professions; centimetres and inches
are
>> still used in about 10 %; and the rest such as butchers (6 %) don't
measure
>> much length anyway.
>>
>>> In any engineering discipline, the mm will be preferable, as it gives
>>> greater precision without the need to resort to decimal places. It
does
>>> end up with more digits on large measurements than the cm does, but
the
>>> greater precision more than compensates for this. If I am doing any
DIY
>>> work, I always measure in mm.
>>
>> To the best of my knowledge, the issue of more digits on large
measurements
>> has never proved to be a problem in any of the trades in Australia. The
>> advantage you mention of not having the need to resort to decimal
places is
>> further enhanced by not having to refer to fractions at all not
common or
>> vulgar fractions and no decimal fractions. There is only pure number
that
>> can be readily manipulated with any cheap calculator.
>>
>>> The comparison between the building industry of Canada and Australia
>>> (the former adopting cm and the latter mm) is illuminating.
Australia's
>>> transition has been more rapid and complete. Even allowing for
Canada's
>>> proximity to a much larger country still using Colonial measure, it is
>>> still reasonable to conclude that choosing the mm was a better
decision
>>> *for that industry*. It is *not* enough to conclude that the mm is
>>> better for all industries.
>>
>> I agree that the comparison between Australia and Canada is valid but I
am
>> on shaky ground in so far as my own personal knowledge of Canadian
>> metrication is concerned. A lot of my conclusions are based on
extensive
>> correspondence with the late Joe Reid, President Emeritus of the
Canadian
>> Metric Association.
>>
>>> Note that for an industry that is converting, there will be a natural
>>> internia against moving away from something familiar. The new units
>>> must offer a significant advantage in order to overcome this. Using
mm
>>> meant moving from awkward constructs such as 3' 5 3/8 " to a whole
>>> number (1034 mm). Where cm are used the conversion is 103.4 cm. The
>>> second is less attractive because you still need the decimal point (a
cm
>>> is too coarse for this type of design to be able to round it off).
Thus
>>> the perceived advantage in going to metric will be less when cm is
used.
>>
>> It's probably worse than you say. Many people when they see 103.4 on
their
>> centimetre tape round this to 103 1/2 because they are used to halves,
>> thirds, quarters, and even eighths of yards, feet, and inches. I have
seen
>> this approach used extensively in the textile industry where I worked
for
>> about 13 years. Of course, carrying you fractional skills and your
mixed
>> number skills (as in could I have 2 metres and 30 centimetres please)
is,
>> in
>> my view, inappropriate and unnecessary.
>>
>>> Comparing the textile and building industries in Australia, and
assuming
>>> that because the former adopted cm and is slower to migrate means that
>>> mm was more appropriate has a subtle flaw. The flaw is the assumption
>>> that if the textile industry had chosen mm, then it would have been
>>> faster. To be able to conclude this, you would need to compare two
>>> textfile industries, one of which converted to cm and the other to mm.
>>> I find no example of this cited in the extensive research.
>>
>> I totally agree with you. Like you, despite extensive searching, I have
not
>> been able to find a single example of any part of the textile industry
who
>> has not chosen the centimetre pathway. However, that said, I have also
>> observed that all of these have, since their centimetre decision,
>> experienced slow, protracted, difficult, and extremely expensive metric
>> conversions most of which have yet to be successful even after some 35
to
>> 40
>> years. I don't think that this is a coincidence, but to concede your
point,
>> I suppose that it could be.
>>
>>> The truth is, for clothing sizes, the cm is the more appropriate unit
to
>>> use. Pre-metric sizes used a resolution of half an inch, which is
very
>>> close to 1 cm.
>>
>> Only for some things is a tolerance of 10 millimetres needed. Shirt
collars
>> are one example. Even there, bespoke tailors eschew measurements and
cut a
>> scrap piece of fabric to fit their client's neck. Neck comfort is
crucial
>> to
>> the performance of a shirt and I prefer personally better fit than 10
>> millimetres. I have been know to move the top button on a troublesome
shirt
>> by about 5 millimetres.
>>
>>> You don't need mm precision for meauring trouser size.
>>> If my waist size is 852 mm, and another person's 847 mm, we will both
>>> take a 85 cm trouser size.
>>
>> If your waist size is 852 mm and you live in Ireland where the
centimetre
>> was chosen as the small measure, your trousers will probably still be
>> offered to you in inch sizes loosely disguised by 'nominal
centimetres'.
>>
>> It works this way. The trouser maker will decided that his 38 inch
waist
>> trousers are his main seller and he will go up and down from there in
lots
>> of 2 inches. To hide the fact that he is not using metric he will
nominally
>> call the median size '97 cm' and then proceed up and down from there in
>> lots
>> of 5 centimetres. His trouser rack will contain these sizes:
>>
>> 82 87 92 97 102 107 112 117 122
>>
>> So, using your examples of my waist size is 852 mm, and another
person's
>> 847
>> mm you will be given the choice between a size 82 and a size 87. Note
that
>> these metric conversions have now subtly become size numbers and not
>> measurements that could be used in a court of law for ill fitting
garments.
>>
>> Young shop assistants soon learn that they have to learn about the real
>> measures in inches behind the 'nominal centimetres' so that they
can be
>> accepted into the community of men's outfitters. I expect that this
policy
>> should last for another 100 or more years.
>>
>>> Being able to group people into standard
>>> sizes is very important in reducing manufacturing costs and shop stock
>>> size.
>>
>> Agreed, and that's why they used an interval of 2 inches in the men's
>> trouser trade and they seem to want this to continue as a rite of
passage
>> for trainee shop assistants. It seems to me to be a power thing rather
than
>> an issue of measurement.
>>
>> As a side issue, the Australian women's clothing trade opted for
>> centimetres
>> with a 5 centimetre interval between sizes but they decided to start at
a
>> hip size of 95 centimetres and then to go up and down from there with
these
>> sizes numbers:
>>
>> 80 85 90 95 100 105 110 115 120
>>
>> Note that these are actual sizes and not the 'nominal centimetres' that
are
>> hidden inch sizes in men's garments.
>>
>>> Trying to use mm means either having a much greater range of sizes
>>> (which impacts costs) or tagging an unnecessary 0 on to every measure.
>>
>> This is not necessarily true. You could still choose to produce a range
of
>> men's trousers using intervals of 50 millimetres.
>>
>> The tagging an unnecessary 0 on to every measure would in fact be an
>> advantage to Australian men who work in the 84 % of Australian jobs who
use
>> millimetres all day every day. You don't have to try and get your head
>> around the centimetres that you haven't used, or even seen since the
day
>> you
>> left school, when you go into a clothing store. You just use the
>> millimetres
>> you have been using all day.
>>
>>> The reason why a transition to metric will not be so fast here is that
>>>
>>> (A) the preceived advantage is not as great: moving from half-inch to
>>> whole cm is nice, but not as attractive as moving from awful fractions
>>> of inches combined with feet to whole numbers.
>>
>> I can see little benefit in a transition from inches, feet, yards, and
>> their
>> attendant halves, thirds, quarters, and eighths, to a regime of
millimetres
>> (for buttons for example), centimetres, and metres that might all be
>> divided
>> into not only halves, thirds, quarters, eighths, and sixteenths, but
also
>> into tenths, hundredths, and perhaps other decimals.
>>
>>> (B) body sizes are some of the most difficult things for people to
shift
>>> units about.
>>
>> I don't agree that 'some of the most difficult things' because if they
are
>> badly planned all metric transitions can seem to be difficult. Recall
that
>> France tried a voluntary metric transition in 1795 this proved to be
too
>> difficult; France then tried a metric conversion by redefining the
aune,
>> the
>> boisseau, the livre, and the toise in metric terms this proved too
>> difficult; and then finally, after almost 50 years they decided to try
>> direct metrication which was successful within a year or so and
they
>> haven't looked back since. In my opinion, it is the process that you
choose
>> for your metrication transition that is most important in providing for
a
>> smooth or difficult metric transition and that is based on the
choices
>> you
>> make when you begin planning your metric transition program.
>>
>>> The real crunch is would the transition have been faster if mm were
>>> chosen. I don't think so. In fact given the unncessary precision
>>> implied, I think it would hinder it (in the same way that people get
>>> turned off metric when they see ridiculously precise conversions).
>>> Whatever chance you have of hoping people will get used to replacing
34
>>> inches by 85 cm there is no chance of 850 mm being accepted.
>>
>> An interesting refutation of what you say happened in the leather and
shoe
>> trade. They have been beset with measurement troubles since the Magna
Carta
>> in 1215, and the subsequent Assizes in 1304, decreed that the barley
corn
>> would be the standard of length for all of England. The shoe makers
chose
>> the length of a barleycorn as their standard 'size' but they did not
yet
>> specify where 'size 0' might be.
>>
>> Because leather is so expensive, modern shoe designers measure in
tenths of
>> millimetres where a shoe might have an overall length of 2800 tenths of
>> millimetres (280 mm) that might be divided as 1000 from the heel to the
>> tongue, 1100 from the tongue to the start of the toe case, and 700 for
the
>> toe case. This shoe would then be labelled with a range of 'Size'
numbers
>> based on the lengths of barley corns. By doing this the shoe maker can
aim
>> for tenths of millimetres accuracy but still leave the actual choice as
to
>> whether the shoe fits or not to the customer's profound knowledge of
barley
>> corns in the 13th and early 14th centuries. Notice that the somewhat
odd
>> choice of tenths of millimetres has allowed the shoe factory workers to
>> avoid fractions altogether.
>>
>>> Measuring people's height is also something in which mm precision
would
>>> be daft. Of course, you can try to split hairs by saying that 174 cm
>>> should be quoted as 1.74 m, thus using meters rather than cm, but you
>>> are still measuring to cm accuracy, so this is really 'hidden
>>> centimeters'. If you are arguing that one of the most powerful
>>> advantages of mm is that it gives you whole integral values (and I
>>> agree) then the same argument applies that 174 cm is easier than 1.74
m.
>>> For reference, I always write my height as "1.74 m" but speak it as
"one
>>> seventy four".
>>
>> I, too, have had trouble with this issue until I realised we could
consider
>> our old estimating abilities in feet and inches. I don't know the
>> experience
>> in Ireland, England, or the USA, but here in Australia, it was usual
for
>> people to guess the heights of others in ever numbers and in lots of 2
>> inches and this translates to 50 millimetres or preferably, in my
opinion,
>> 0.05 metres.
>>
>> I once spent some time training police officers and the estimation of
>> heights was a critical daily issue for them. They were used to guessing
in
>> lots of 2 inches, viz: 5'2". 5'4", 5'6", 5'8", 5'10", 6'0", 6'2", 6'4",
>> 6'6", and so on. I tried unsuccessfully to teach them about centimetres
and
>> they absorbed this in the same way as the tailors. They took 6'0" to be
183
>> centimetres and then moved up and down from there. Their series went
like
>> this:
>>
>> 158 163 168 173 178 183 188 193 198
>>
>> Clearly this encouraged young police officers to learn about inches
from
>> their senior colleagues because these were the true underlying
measures.
>>
>> I then chose to use metres in the form of decimal numbers with two
decimal
>> places that were to be ended in either a '5' or a '0' and trained them
to
>> use standard doorways (2.05 metres) and their own heights (generally
huge
>> they were big men) to guess the heights of the people around them. This
>> technique proved to be successful and with a little training they
became
>> quite accurate. I suppose that I could have persisted with centimetres
but
>> I
>> didn't and the added benefit was that these officers became quite
>> interested
>> in calculating their Body mass Index using their mass in kilograms and
>> their
>> height in metres.
>>
>>> I would certainly agree that in most industries, mm should be chosen
>>> rather than cm as the increased precision and whole numbering is
>>> decisive. But this doesn't mean it is *always* appropriate, and it
>>> certainly should not mean that the cm should be 'deprecated',
>>> particularly in everyday use. The cm is a very handy size for
>>> approximate measure, and the last thing you should do when you are
>>> trying to get people to convert to metric in their everyday life is to
>>> try and force them to use something less convenient.
>>
>> But this is my exact point. The centimetre is not more convenient
because
>> it
>> (always?) brings with it the old baggage of fractions. Consider the
problem
>> of the software engineers at Microsoft when they wrote Microsoft Word.
If
>> you try to change your default rulers to metric you have two choices:
>> centimetres or millimetres, where the centimetres are divided into
quarters
>> and the millimetres are arranged in lots of 2 1/2.
>>
>> The other issue that centimetres bring in a metric transition is metric
>> conversion. People seem to think that it is appropriate to convert from
>> centimetres back to inches. This is time consuming and enormously
>> inefficient. In a large textile mill it is interesting to watch the
>> interactions between the machine operators and the technicians who
repair
>> and set up the machinery. The latter use millimetres exclusively while
the
>> former use a combination of centimetres and inches it leads to some
>> strange conversations.
>>
>>> Lastly, the only metric quantity that all Americans understand and are
>>> completely familiar with is money. Everyone knows that $1.84 and 184
c
>>> amount to the same value. This parallel with meters and centimeters
is
>>> too good a comparison to miss when trying to convince people that the
>>> metric system is actually easier than what they are using (explain
>>> pounds, shillings and pence to them, and they will agree this was an
>>> awful cumbersome system; then point out that they are using the
>>> equivalent in measuring everything else).
>>
>> What you say is true, but you and I both know that there is another
reality
>> emerging from behind the closed doors of metrologists, engineers,
>> architects, and other professional metric unit users, and this is the
>> preference for metric prefixes that are represent in groups of three
>> decimal
>> places. This use of preferred prefixes has already, more or less,
killed
>> off
>> deci, deca, and hecto, and now centi is the only one of the original
metric
>> system prefixes left. Let me repeat, I know the status of the
centimetre
>> both historically and in the current BIPM brochure so their demise is
due
>> to
>> movements in the perception of practical value rather than in their
formal
>> acceptance by metrology officials.
>>
>>> So please lay off the centimeter. Just because it is not as
appropriate
>>> to adopt in the case of the clear majority of industries does not mean
>>> it is not a useful, widely accepted and 'perfectly good' metric unit.
>>
>> I know that I stand alone on this issue, but I am also aware that if
anyone
>> who is about to choose a metrication pathway chooses to use centimetres
>> they
>> are in for a difficult, slow, and expensive transition to the metric
system
>> and my only goal in talking about the centimetre at all is to try and
help
>> others avoid that fate. I've been there in the textile industry and it
was
>> not a happy experience. I, for one, will not be using the value laden
>> adjectives 'perfectly good' when I am discussing the centimetre.
>>
>> Cheers and thanks again for the opportunity to explore this important
issue
>> further,
>>
>> Pat Naughtin
>> PO Box 305, Belmont, 3216
>> Geelong, Australia
>> Phone 61 3 5241 2008
>>
>> Pat Naughtin is the editor of the free online monthly newsletter,
>> 'Metrication matters'.
>> You can subscribe at http://www.metricationmatters.com/newsletter
>>
>> Pat is also recognised as a Lifetime Certified Advanced Metrication
>> Specialist (LCAMS) with the United States Metric Association. He is
also
>> editor of the 'Numbers and measurement' section of the Australian
>> Government
>> Publishing Service 'Style manual for writers, editors and printers'.
He
>> is
>> a Member of the National Speakers Association of Australia and the
>> International Federation for Professional Speakers. See:
>> http://www.metricationmatters.com
>>
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