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SpaceMelon
2005-Jan-17, 03:59 PM
When was the metric system declared “base” system for Astronomic Mathematics?

I've been trying to fiend some information on this for a school project but all my searches have, sadly, come up empty.
So I’m hoping someone here could help me? It would be much appreciated.

-SpaceMelon

Fortis
2005-Jan-17, 04:30 PM
There's a lot of info on this site about SI
http://www.bipm.org/en/home/

The International Union of Pure and Applied Physics is here
http://www.iupap.org/

And the International Astronomical Union is here
http://www.iau.org/

Between them you may find out what you're looking for.

(I suspect that SI was adopted by various scientific disciplines at about the same time as it adopted by the General Conference on Weights and Measures back in 1960, but as you're looking for something a bit more authoritative you may need to do a bit more digging. :) )

Bawheid
2005-Jan-17, 04:49 PM
Welcome, SpaceMelon.

beezlebug
2005-Jan-17, 04:57 PM
Unfortunatly, not everyone always realised that metric WAS the standard. Remember the Mars Climate Orbiter?

dgavin
2005-Jan-17, 05:17 PM
Astronomers normally use the metric system for a variety of reasons.

The Meter was origionally designed by an astonomer based on 1 arc minute of distance, which equates to a 40000km Circumfrance of earth. It has since been redefined to be the distance light travels in 1/299,792,458 of a second, or for ease, light travels 29.97 meters in a micro second.

The history of this standard is varied, and the only hold out not using it is the Unitied States. Even though the US was instrumental in getting it established as the International Standard.

As to when it was designed in 1670 by a french astronomer.

for details...http://lamar.colostate.edu/~hillger/origin.htm

Evan
2005-Jan-17, 05:25 PM
The mistake with the MCO totally mystifies me. As a child in the US in the sixties I learned metric. When I hung out with my father at the Lawrence Rad Lab they always used metric. In his science classes he always used metric. The fact that a computer program was written to use feet per second units baffles me.

Tom Ames
2005-Jan-17, 05:34 PM
In molecular biology metric has always been standard. Any time you have to deal with quantities that vary over several orders of magnitude (such as solute concentrations) this only makes sense. Also, international standards make a lot of sense in science. (For the same reason English is the de facto language of science.)

Engineers don't often have to go from feet to nano-feet, so the advantages of metric are not so obvious. Also, My understanding is that standards for engineering practices are defined on a national (or state) level, so the international concordance is not so important.

Still, you'd think the Lockheed engineers would at least realize that OTHER people use metric!

Fortis
2005-Jan-17, 05:43 PM
The mistake with the MCO totally mystifies me. As a child in the US in the sixties I learned metric. When I hung out with my father at the Lawrence Rad Lab they always used metric. In his science classes he always used metric. The fact that a computer program was written to use feet per second units baffles me.
True, but there have always been hold outs out there. For example pilots still work in knots, and I can remember using diffraction gratings that were specified in lines per inch. (IIRC the shuttle uses knots and nautical miles, which alledgedly led to a cockup with a shuttle based experiment in the '80s, thoughh I could have this completely wrong. :) )

Kaptain K
2005-Jan-17, 06:31 PM
...light travels 29.97 meters in a nano second.
I believe tha's 0.2997 meters/nanosecond! :o

dgavin
2005-Jan-17, 07:16 PM
GAK,

sorry it's 29.97 Metters per microsecond. I stand corrected.

Ut
2005-Jan-17, 07:34 PM
SI isn't the standard in astronomy. They confound us with cgs units, after having drilled SI's mks units into our heads all our lives. And if you're not lucky, whoever is teaching your astronomy lectures will not understand that you have no freaking clue what an erg is.

Evan
2005-Jan-17, 07:51 PM
sorry it's 29.97 Metters per microsecond. I stand corrected.

No, it is 299.7 meters per microsecond.

John Dlugosz
2005-Jan-17, 08:07 PM
The mistake with the MCO totally mystifies me. As a child in the US in the sixties I learned metric. When I hung out with my father at the Lawrence Rad Lab they always used metric. In his science classes he always used metric. The fact that a computer program was written to use feet per second units baffles me.

There are also 2-digit years and non-Unicode character sets in new programs. At least they stopped using 32-bit numbers for the size of a file and/or free space on a disk, once the problem became widespread enough in the mainstream.

--John

01101001
2005-Jan-17, 08:48 PM
sorry it's 29.97 Metters per microsecond. I stand corrected.

No, it is 299.7 meters per microsecond.

Heh. I thought this metric stuff was supposed to make things easier!

~ .9836 feet per nanosecond.

Doodler
2005-Jan-17, 08:54 PM
~ .9836 feet per nanosecond.

A foot with clipped toenails, close enough for gummit work. :)

Saluki
2005-Jan-17, 09:19 PM
Just a nit pick. The Metric system is outdated, and is no longer (formally) used. The SI (Le Systemme International D'Unites) replaced it many decades ago. Both systems use similar units, but many archaic Metric Units (calorie, centimeter, etc) have no place in SI.

Evan
2005-Jan-17, 09:53 PM
???

Centi is an SI prefix and meter is the SI unit of length therfor centimeter is a legitimate SI unit.

Saluki
2005-Jan-17, 10:26 PM
Ok, I checked and I was wrong about cm. We engineers think in powers of 10 evenly divisible by 3. I forgot the rest of the world still used the less convienient prefixes. :oops:

However SI does exclude derived units based on cgs such as ergs and dynes.

archman
2005-Jan-17, 10:48 PM
The history of this standard is varied, and the only hold out not using it is the Unitied States. Even though the US was instrumental in getting it established as the International Standard.
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Liberia and Myanmar are also recognized as "holdouts", although they (and the U.S.) have joined all other nations in official adoption of the metric system. Formal declaration and mainstream incorporation are two different beasts, however.

Nicolas
2005-Jan-17, 10:51 PM
"centimeter" is used extremely much in Europe. Only in engineering calculations we say .10^-2 m. All our rulers (how do you call all these things) geometric devices, etcetc, well anything that measures lengths between 10 m and 5 cm is divided into centimeters (and millimeters). People don't thing of it as "centi-meter" it is just a word in daily use, it is so common to us.

Nicolas
2005-Jan-17, 10:59 PM
For example pilots still work in knots

I heard a story, but I've forgotten the details. It was something like this:

It was proposed to use the metric system in Europe. Russia made all their planes in metric system (double readouts), to be allowed to fly in Europe. Only, the proposal never came through. Now the Russians are the only ones flying with a metric system.

Andreas
2005-Jan-17, 11:43 PM
For example pilots still work in knots

I heard a story, but I've forgotten the details. It was something like this:

It was proposed to use the metric system in Europe. Russia made all their planes in metric system (double readouts), to be allowed to fly in Europe. Only, the proposal never came through. Now the Russians are the only ones flying with a metric system.
European countries used to have a mixture of units used in aviation. At least Germany was fully metric, France I think also was or at least was mostly metric, UK used miles per hour for speed I think and so on. Well, Germany lost WW2 and German aviation was shut down in the aftermath, and the allied forces taking over were rather unmetric. The Soviets on the other hand didn't lose and kept their metric aviation.

After the ICAO was founded and standardized on what most aviation used now, the Soviets of course didn't enthusiastically follow those old-fashioned imperialist units. :wink: I think the ICAO states requires that all commercial aviation follows their standards, so I guess Aeroflot planes travelling to those (most of Europe, for example) need double instrumentation to be allowed there.

And the Russians aren't the only ones metric. After sailplane flying was allowed in Germany again, they didn't follow the commercial aviation world, so thankfully gliders are still fully metric here. :) (Not only in Germany of course.)

Evan
2005-Jan-17, 11:49 PM
Canada has been officially metric since 1975. There are some odd results that were not fully anticipated. For instance, nearly all building materials are still made in imperial units such as a 4' x 8' sheet of plywood or a 2"x4" piece of lumber. However, roofing shingles switched over soon after metrification which means you cannot repair an old roof. I smell a plot by the roofing industry.

All food products are sold by metric weight/volume which I find much easier for price comparison shopping. Hiways signs, weather, distances are all metric. The younger generation such as my grandchildren have no clue what an inch or a yard is. Oddly enough although I prefer metric I still use the imperial system a lot. That is because I have a machine shop at home and all my equipment is inch based as certain items like my lathe was made in 1937. Also, although metric hardware is available it is still much easier to find UNC and UNF hardware (imperial units).

It will be a long time before the changeover is anything close to complete and I am sure that certain things will never change. For example every country in the world uses socket handles that have 3/8" and 1/2" square drives regardless of what socket goes on it metric or not.

The odd thing about machining is that even though all of my equipment is SAE I do everything in decimal fractions. All measurements are in thousandths, hundreths and tenths etc. That has been the case for a very long time. It's a bit funny sometimes. I hang out on a machinist BBS and if you really want to see the fur fly just start a topic about metric vs imperial.

Trebuchet
2005-Jan-18, 12:48 AM
... or a 2"x4" piece of lumber...

Which is of course, a perfectly logical 1.5 x 3.5 inches in actual dimensions!

Evan
2005-Jan-18, 12:56 AM
A 2x4 actually is 2x4 before it is run through the planer.

frogesque
2005-Jan-18, 01:52 AM
A 2x4 actually is 2x4 before it is run through the planer.

Actually it's 2x4 less the width of the saw cut on both sides (approx 1/8") for rough sawn timber (UK) so it's about 1+7/8 x 3+7/8 after conversion.

ChaosInc
2005-Jan-18, 02:38 AM
I just wished they had fudged the meter a bit to make g=10m/s.s, of course that only applies on earth, but that happens to be where I live! I don't think Bar is officially SI, but seems more intuitive to use compared to kPa. And, is the 2X4 measured prior to being dried?

Ut
2005-Jan-18, 05:49 AM
Just a nit pick. The Metric system is outdated, and is no longer (formally) used. The SI (Le Systemme International D'Unites) replaced it many decades ago. Both systems use similar units, but many archaic Metric Units (calorie, centimeter, etc) have no place in SI.

Just a nit pick of my own. The mass of the sun is measured in grams, the AU is defined in relation to the centimetre, and solar flux is measured in ergs/cm^2*Hz. Spectral lines are commonly measured in angstroms, and the jansky doesn't appear in the SI listings anywhere.

Kaptain K
2005-Jan-18, 08:49 AM
Spectral lines are commonly measured in angstroms...
Which is no big deal, since dividing by 10 gives nanometers.

Manekineko
2005-Jan-18, 11:11 AM
You mean multiplying by 10... 10 angstroms in 1 nm. 8)

Nicolas
2005-Jan-18, 12:04 PM
the AU is defined in relation to the centimetre

Wouldn't that be the metre? The metre is the ground unit of length.
I was always tought in school that the kilogram was the ground unit of weight. This always seemed very strange to me, considering the prefix "kilo"... I am a bit skeptic on my teachers concerning this...

Also, here in the Netherlands at my university and in several books, all SI units are used, only they loose it on speed. Very often "V" is used, while it should be "v". I really don't know what is so difficult about using that one correct, but they almost always fail in it. And when discussing volumes (which should be V) and speeds in aerodynamics, this is rather frustrating...

Argos
2005-Jan-18, 12:50 PM
Inches, knots and nautical miles are still used in countries that adopt the metric system. Carpenters measure nails in inches around here. But don´t ask a South American how many kilometers make up a mile.

Disinfo Agent
2005-Jan-18, 01:46 PM
I was always tought in school that the kilogram was the ground unit of weight. This always seemed very strange to me, considering the prefix "kilo"... I am a bit skeptic on my teachers concerning this...
From here (http://physics.nist.gov/cuu/Units/current.html):


The kilogram is the unit of mass; it is equal to the mass of the international prototype of the kilogram.

It is important to note that the kilogram is the only SI unit with a prefix as part of its name and symbol.
I guess one gram(me) is too little to be used as a prototype.

Nicolas
2005-Jan-18, 01:50 PM
One gram is indeed small for a prototype object, but it could have been defined as 1/1000th of the mass of that prototype of course...

Nowhere Man
2005-Jan-18, 02:14 PM
IIRC, one gram is the mass of a cubic centimeter of water at STP. One thousand cubic centimeters (10 by 10 by 10) is a liter, so a liter of water at STP masses one kilogram.

Fred

Disinfo Agent
2005-Jan-18, 02:30 PM
At the end of the 18th century, a kilogram was the mass of a cubic decimeter of water. In 1889, the 1st CGPM sanctioned the international prototype of the kilogram, made of platinum-iridium, and declared: This prototype shall henceforth be considered to be the unit of mass. The picture at the right shows the platinum-iridium international prototype, as kept at the International Bureau of Weights and Measures under conditions specified by the 1st CGPM in 1889.

*******The 3d CGPM (1901), in a declaration intended to end the ambiguity in popular usage concerning the word "weight," confirmed that:


The kilogram is the unit of mass; it is equal to the mass of the international prototype of the kilogram.

historical context - the kilogram (http://physics.nist.gov/cuu/Units/kilogram.html)
I guess that, since merchants often need to weight small amounts of material in scales, it made sense for the original unit to be small.

A Thousand Pardons
2005-Jan-18, 02:49 PM
The Meter was origionally designed by an astonomer based on 1 arc minute of distance, which equates to a 40000km Circumfrance of earth.

::snip::

As to when it was designed in 1670 by a french astronomer.

for details...http://lamar.colostate.edu/~hillger/origin.htm
Details are there, but you have misstated them. It says one of the original proposals was 1 minute of arc of a great circle of the earth, but one minute of arc is over a mile--in fact, it's just about a nautical mile.

I just wished they had fudged the meter a bit to make g=10m/s.s, of course that only applies on earth, but that happens to be where I live!
It (g) varies, from pole to equator, but the original definition of the meter was to be that of the seconds pendulum--the length of a pendulum that takes one second to swing from side to side (see dgavin's link). They realized that this was too variable, so they decided to base it on an Earth measurement (and get government funding for the expedition), and they found that the seconds pendulum was just about 1/10^7 of a quarter of an earth circumference. That also appealed to their sense that things should be in powers of ten.

Had they stuck with the original seconds pendulum definition of the meter, then the acceleration of gravity would be exactly pi^2 m/s/s (9.8696 m/s/s) instead of just approximately.

ToSeek
2005-Jan-18, 02:56 PM
It says one of the original proposals was 1 minute of arc of a great circle of the earth, but one minute of arc is over a mile--in fact, it's just about a nautical mile.

Isn't it exactly a nautical mile, by definition?

A Thousand Pardons
2005-Jan-18, 03:08 PM
It says one of the original proposals was 1 minute of arc of a great circle of the earth, but one minute of arc is over a mile--in fact, it's just about a nautical mile.

Isn't it exactly a nautical mile, by definition?
Close enough, but it can't be exact for three reasons: not all great circles have the same length, one minute of arc has a different length at different places, and there is more than one definition of "nautical mile" I just checked a dictionary and the International nautical mile seems to be the same as the USAn one, and they are both 1852 meters, which would put the radius of the earth at 6366.7 km. The same reference says that the average radius is 6374 km (it varies by over 20 km).

Kaptain K
2005-Jan-18, 03:12 PM
You mean multiplying by 10... 10 angstroms in 1 nm. 8)
No, I meant what I said:
5000 Angstroms (green light) divided by 10 equals 500 nanometers!

Doodler
2005-Jan-18, 04:35 PM
A 2x4 actually is 2x4 before it is run through the planer.

Actually it's 2x4 less the width of the saw cut on both sides (approx 1/8") for rough sawn timber (UK) so it's about 1+7/8 x 3+7/8 after conversion.

Which is why 2x4 is considered a nominal size for finish lumber, not the actual dimension. In the United States its less accurate than that. My office designs concrete tilt panels which are formed on the floor slab of a building and lifted into place to become the outer walls with a standard thickness of 7 1/4". The reason for this is that a 2x8 board used in the panel form has an actual measured width of 7 1/4". A nominal 2x4 piece of lumber is actually closer to 1 1/4" or 1 1/2" thick by 3 1/4" wide on this side of the Pond.

Evan
2005-Jan-18, 05:07 PM
The concept of nominal size no longer has any meaning. The town I live in is one of the largest producers of lumber in North America. My wife manages a business that sells products directly to the mills saw filing and planer rooms and my son in law is qualified on every machine in a modern sawmill. Typically, after debarking a log will be gang sawed to length on the "merch deck". It is then fed to the canter which cuts cants and boards. The centre cants may be directed to a true shape vertical curve sawbox which is able to cut straight pieces from curved logs. It is at this point that nominal size loses its meaning as the boards are cut as close as possible to finish size to maximize production.

A 2x4 will never have been close to 2x4 and is cut perhaps only 1/8" above finish size before it goes to the edger and planer.

Ut
2005-Jan-18, 05:36 PM
the AU is defined in relation to the centimetre

Wouldn't that be the metre? The metre is the ground unit of length.


Again, astro texts are written in cgs units. centimetres, grams, seconds. Those are the base metric units used in astronomy.

And it's bloody annoying.

Nicolas
2005-Jan-18, 06:02 PM
Quite annoying indeed, centimetres at such scales :)

A Thousand Pardons
2005-Jan-18, 06:10 PM
So you all prefer 1.5 x 10^8 instead of 1.5*10^13? :)

Metricyard
2005-Jan-18, 07:31 PM
I always assumed that the metric system would be used exclusively when building probes or anything involving space exploration.

What probe was it that got screwed up because of a conversion failure? (thought it was the beagle lander? Can't recall). Shouldn't it be required to use the metric system across the board, especially now that there's alot more co-operative missions around the globe? What reason would an aerospace company not want use the metric system other then political reasons?

I can't believe that in the beginning of the 21st century that all scientific endevours would use anything other then the metric system.

01101001
2005-Jan-18, 07:41 PM
What probe was it that got screwed up because of a conversion failure? (thought it was the beagle lander? Can't recall).
Mars Climate Observer (http://mars3.jpl.nasa.gov/msp98/orbiter/)

Metricyard
2005-Jan-18, 08:21 PM
What probe was it that got screwed up because of a conversion failure? (thought it was the beagle lander? Can't recall).
Mars Climate Observer (http://mars3.jpl.nasa.gov/msp98/orbiter/)

Thanks, that's the one.

But this is what I was getting at. Wouldn't a lab like JPL require tthat all information like this be in the same numbering system? It would be a pain in the but to have to go over every piece of code/schematics checking if the numbers used were in metric or english measurements.

harlequin
2005-Jan-18, 08:43 PM
The mistake with the MCO totally mystifies me. As a child in the US in the sixties I learned metric. When I hung out with my father at the Lawrence Rad Lab they always used metric. In his science classes he always used metric. The fact that a computer program was written to use feet per second units baffles me.

I think the bafflement should be in worse than you state.

In the end it really should not have been a big deal something was developed using feet per second (though it does seem strange when science is done in metric). With proper documentation (as should be done with any professional development) it would have been immediately obvious that different aspects were using different units before the thing was even launched. Whenever there is an input or output, the documentation (including comments in the source code itself) should clearly and explicately state what units the input is expected to be in and what units the output is in. No exceptions of this should be ever made.

If this had been done then the people putting the whole thing together would have noticed that one component used f/s and the other m/s and would have either requested one be rewritten to metric or (more likely) spent five minutes to write a function to to convert to metric.

Sloppy work is more at fault then someone's unusual choice in units.

John Dlugosz
2005-Jan-18, 09:32 PM
The mistake with the MCO totally mystifies me. As a child in the US in the sixties I learned metric. When I hung out with my father at the Lawrence Rad Lab they always used metric. In his science classes he always used metric. The fact that a computer program was written to use feet per second units baffles me.

I think the bafflement should be in worse than you state.

In the end it really should not have been a big deal something was developed using feet per second (though it does seem strange when science is done in metric). With proper documentation (as should be done with any professional development) it would have been immediately obvious that different aspects were using different units before the thing was even launched. Whenever there is an input or output, the documentation (including comments in the source code itself) should clearly and explicately state what units the input is expected to be in and what units the output is in. No exceptions of this should be ever made.

If this had been done then the people putting the whole thing together would have noticed that one component used f/s and the other m/s and would have either requested one be rewritten to metric or (more likely) spent five minutes to write a function to to convert to metric.

Sloppy work is more at fault then someone's unusual choice in units.

If they were just consistent and used feet for everything in their subsystem, it would have been obvious too 'cause the holes would not line up. :D

Manekineko
2005-Jan-19, 11:18 AM
You mean multiplying by 10... 10 angstroms in 1 nm. 8)
No, I meant what I said:
5000 Angstroms (green light) divided by 10 equals 500 nanometers!
:oops: Apologies... I should have read it more carefully.

01101001
2005-Jan-19, 08:45 PM
You mean multiplying by 10... 10 angstroms in 1 nm. 8)
No, I meant what I said:
5000 Angstroms (green light) divided by 10 equals 500 nanometers!
:oops: Apologies... I should have read it more carefully.
Well, Kaptain K could have been clearer by including the units (and thus actually multiplying or dividing by 1):

5000 A / (10 A/nm) = 500 nm
5000 A * (1 nm/10 A) = 500 nm

A Thousand Pardons
2005-Jan-20, 12:48 AM
You mean multiplying by 10... 10 angstroms in 1 nm. 8)
No, I meant what I said:
5000 Angstroms (green light) divided by 10 equals 500 nanometers!
:oops: Apologies... I should have read it more carefully.
Well, Kaptain K could have been clearer by including the units (and thus actually multiplying or dividing by 1):

5000 A / (10 A/nm) = 500 nm
5000 A * (1 nm/10 A) = 500 nm
Here's his original:


Spectral lines are commonly measured in angstroms...
Which is no big deal, since dividing by 10 gives nanometers.
Couldn't be any clearer.

Philippe
2005-Jan-20, 05:48 PM
You want a good metric vs. imperial measurement story? Check the story of the Gimli Glidder.

http://www.wadenelson.com/gimli.html

It's the story of what happens when you don't put enough fuel in a Boing 767...

Here's how the mistake happened...


Among other things, the specific gravity of jet fuel is needed to make the proper "drip" calculations.

The flight crew had never been trained how to perform the calculations. To be safe they re-ran the numbers three times to be absolutely, positively sure the refuelers hadn't made any mistakes; each time using 1.77 pounds/liter as the specific gravity factor. This was the factor written on the refueler's slip and used on all of the other planes in Air Canada's fleet. The factor the refuelers and the crew should have used on the brand new, all-metric 767 was .8 kg/liter of kerosene.

After a brief hop Flight 143 landed in Ottawa. To be completely safe, Pearson insisted on having the 767 re-dripped. The refuelers reporting the plane as having 11,430 liters of fuel contained in the two wing tanks. Pearson and Quintal, again using the same incorrect factor used in Montreal, calculated they had 20,400 kilos of fuel on board. In fact, they left for Ottawa with only 9144 kilos, roughly half what would be needed to reach Edmonton.

Evan
2005-Jan-20, 06:03 PM
I know the incident but:
each time using 1.77 pounds/liter as the specific gravity factor. This was the factor written on the refueler's slip and used on all of the other planes in Air Canada's fleet. The factor the refuelers and the crew should have used on the brand new, all-metric 767 was .8 kg/liter of kerosene.

1.77 lbs and .8kg are the same. So where is the mistake?

A Thousand Pardons
2005-Jan-20, 06:05 PM
I know the incident but:
each time using 1.77 pounds/liter as the specific gravity factor. This was the factor written on the refueler's slip and used on all of the other planes in Air Canada's fleet. The factor the refuelers and the crew should have used on the brand new, all-metric 767 was .8 kg/liter of kerosene.

1.77 lbs and .8kg are the same. So where is the mistake?
I had the same question. They ignored the units, and just used the wrong conversion factor, apparently. Unfortunately, the same thing can happen wholly within the metric system--if they're dumb enough to ignore the units, then they might multiply when they should be dividing.

lti
2005-Jan-20, 09:18 PM
Coming from New Zealand i have grown up with metric.
Since almost everything we watch on discovery or national geographic comes from america, they frustratingly use imperial.

It makes it difficult to take information out of a show when theyre talking about things like inches or pounds when u have no reference for how much they actually are.

Im in university studying engineering at the moment, and what really makes metric so effective are the units (:p). What i mean is, you can easily solve problems simply by looking at the units. In physics exams at school we lost marks for not including the units of our results. we thought it was cruel then, but now i see that without the unit ur value is meaningless. Air Canada could learn a thing or two:P.

What i always find fun is playing around with units that mean the same thing
1 N = 1 Kgms^-2 (1 Newton = 1 Kilogram meter per second per second)
(google is good to use for this)

A Thousand Pardons
2005-Jan-21, 05:33 AM
what really makes metric so effective are the units
If only someone had pointed this out before, the USA would not be in such a mess today :)

Manchurian Taikonaut
2005-Jan-21, 09:45 AM
Unfortunatly, not everyone always realised that metric WAS the standard. Remember the Mars Climate Orbiter?

so what went wrong, was it designed using the wrong standard ?

EDIT : Never mind I found a link in this thread.

Ut
2005-Jan-21, 03:35 PM
... but now i see that without the unit ur value is meaningless. Air Canada could learn a thing or two:P.

You mean blue collar airport fuel monkeys who have been so programmed to as be dulled to anything but the number, and who grew up in the 70's in Canada with strange units like pounds/litre and probably don't have a working clue as to what a kilogram is could learn a thing or to. And did. The hard way.

A system of units is only as convenient as ones ability to use them. I myself have grown up in Canada under the metric system. But I think in pounds, feet, and inches, as well as kilograms, centimetres, metres, litres, kilometres, etc. Inches, centimetres, feet, and metres are interchangeable in my head and can be used at convenience. It's a lot easier to reference "1 foot" than it is "30 centimetres", or "~1 inch" than "2.5 centimetres". "1 pound" trumps ".5 kilos (even if it is only .454 kilos).

I don't know the temperature in F, or g in ft/s. I can't measure densities in lbs, or volumes in cubic inches, ounces, or the like. Why not? No exposure. Well, there are a rediculous number of people in Canada who still don't know what a kilogram is, but they'll go "Oh yeah! I remember that from school" if you tell them.