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Science

Mars Orbiter Lost Over Metric Conversion Error 623

Buxley writes "NASA is reporting that they've found the likely cause for last week's loss of the Mars Climate Orbiter. It seems one of the engineering teams was using English units of measurement while another team was using Metric units. Getting this straight is rather important when designing navigation sytems for interplanetary spacecraft, one would think." A lot of people sent this one in; thanks to all. And if this event doesn't prove that it's time for the U.S. to go 100% metric, I don't know what will. Oy!
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Mars Orbiter Lost Over Metric Conversion Error

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  • I used to be an engineering machinist for a Swiss multinational in England. We used the "Metric inch" as we used both metric and imperial measurement. The big advantage of the metric inch is that it gives 1mm=40 thou.

    The metric inch was adopted as the ISO (International standards organization) standard quite a long time ago now, though I don't know the ASA (American Sytandards Association) position on this.
  • Speaking of high bases, I think the ancient Japanese numbering system originally had a different character for each number (and a different name) way into the hundreds! That's news to me. Japan imported its characters from China, which has used a base 10 system since time immemorial. Japanese does have an assortment of characters for representing numbers to 10^72, but this is no different from Latin terms like "quadrillion".

    However, the Oksapmin of Papua New Guinea use a baseless numbering system, where each number is one of 27 body parts.

    "I'll take left ankle apples and a pinkie of oranges, thank you..."

    Cheers,
    -j.

  • >Next you'll be telling us that it makes more sense to drive on the right side of the road as opposed to the left.

    It actually does. You see it's been proven statistically the left handed people often accidently turn the can _into_ traffic when they try to avoid something. And since most people are right handed, driving on the left will _increase_ the risk of serious traffic accidents.




    LINUX stands for: Linux Inux Nux Ux X
  • I always find it amusing that whenever the U.S. doesn't go along with everyone else, it's "not-invented-here", "arrogance", we're "insular" or what have you. Whenever a European country doesn't go along it's "tradition", or "protecting their culture". Oh well, do what you like...

    BTW, when are you Brits going to get with the program and drive on the right-hand side of the road like everyone else ;)
  • Another incident where incorrect metric conversions were blamed was the so-called "Gimli Glider" where, back in 1983, an Air Canada 767 ran out of fuel mid-flight. The amount of fuel on the plane had been calculated incorrecly due to a mixup in the units involved. The pilot amazingly flew the plane (now a 132-ton glider) without power and landed safely at a WWII-era airport turned racetrack in Gimli, Manitoba. An account of the incident can be found here [chemcenter.org].

    I originally read about it in Reader's Digest, and, not surprisingly given their conservative bent, they claimed the accident was really the Canadian government's fault, because they were forcing conversion to the metric system.
  • For this purpose, english units are superior on a small scale such as this.

    I don't understand where you get this. There is a finite number of "tick" marks you can make on a ruler regardless of the measurment system in use.

    You can either go with 1/32nd inch increments or 1mm increments (slightly less dense). 1/2 of an inch or 1cm increments. I totally don't understand your objections on precision. Instead of saying, "1/16th of an inch!" say "2 millimeters!"

    As many other posters have pointed out, it all boils down to the fact that you're accustomed to the Imperial units, so those units (and their various fractions) seem like "natural" units of measure. It's just a mind-set that must be overcome.
  • But the integration of all the units is so much easier with Metric. A Joule is the energy lifting one kg one meter in the air. [...]

    Survey says...

    E = mgh

    m = 1 kg

    g = 9.8 m/s^2

    h = 1 m

    E = 9.8 joules

    You forgot the accelleration of gravity.

  • "English System"? What's that? "Imperial mishap"? NASA and some emperor?

    Everyone knows precisely what "metric" means. To write a headline that accurately described the problem would have to include something like "English System of Measurment" or "Imperial Units of Measure", both of which are rather lengthy for a headline.

    They aren't being biased against Metric, they were just trying to write a clear, concise headline that described the article in as few words as possible. Using the word "metric", while seeming to offend the easily offended (and conspiracy theorists), was nevertheless a logical choice.
  • If everyone would simply accustom themselves to Metric measurments, it might make the process a lot easier.

    As it is now, all street signs use strictly English units. It's going to cost a lot, but I think one of the first things that should be done is to start going through and replace the existing signs with ones that also have Metric units. All new signs would have both also. Start making gas pumps and signs "bilingual".

    As far as legislation goes, I would have no problem with laws that require all new signage containing a unit of measurment have that measurment dominantly in Metric. ("350mL (11.5 Fl. Oz)" instead of the other way around.) Old/never updated signs can stay the way they are for all I care, but this law would apply to both new signage *and* all government-controled signs (road signs).

    Kids today spend much more time with Metric than they do with English units. Once they get out of school, however, and enter the Real World, EVERYTHING uses English units. Most kids never deal with Metric again, so they lose their proficiency and embrace English units. If we adopted a policy of signs that use both (or simply Metric), it would be very easy for kids to "convert". Yes, it will be harder for the older folks that no longer know the difference between a gram and a liter, but eventually those people will be dead, and it won't matter.
  • Scaling is not easy with paper as you need to multiply the sides by root 2 ( 1.41 and a bit ) it would be easier to use 1.5. It only scales easily if you rotate through 90 degrees first.
  • Switching to metric means picking which metric

    Could you elaborate on this? What two "families" of Metric are you referring to?

    and then redesigning almost everything from the ground up

    Surely you're exaggarating. Tools are readily available in Metric. Machines for building parts and tools are readily available in Metric. Flip your ruler over and you've got Metric.

    I do agree, though, that designs based upon existing English unit-based designs will probably need to stick to English units. Nobody's saying you *have* to convert these designs, but unless your entire business is working with older mechanical designs, you can at least start designing new things using Metric. Or don't. I don't really have a problem with firms that, for whatever reason, have to continue using non-Metric units internally. So long as it doesn't affect me (I don't have to repair or work with it). As the rest of the country makes the conversion, though, you may have a hard time finding employees who are willing to stick with those units, however.

    For everyone else, for those that don't necessarily have to work with aged designs, it shouldn't be terribly difficult to switch. You'll probably find that most fresh faces are accustomed to working in both units of measure. They usually would have no qualms about working for a Metric-based firm or a non-Metric-based firm, but once they start, those units become harder to let go of.

  • But has anyone thought about how a ridiculously bureaucratic organisation such as NASA can implement these changes before the sun runs out of fuel?

    Easy. Make further funding for NASA contingent upon them being able to change to metric. And all that takes is the cooperation of Congress.

    Oh. (realizing what I've said) Nevermind.

  • I wasn't seriously suggesting that the article be called "English System mishap caused loss of NASA orbiter" -- this was just an example to clarify my point. A more appropriate title would have been something like "Unit mixup caused loss of Nasa orbiter". The present title isn't even accurate and is highly misleading -- at first glance it seems as though the problem was caused by some silly engineers using the metric system when everyone else in NASA was using english units (in fact it was the other way around); but maybe you think that the shortness of a headline is more important than accuracy.

  • I for one think that the inch is far to small....
    Lets all start using feet and then split the feet into 5.34 for a sub-measurement of .187265 feet and call it a mini-foot.....I'm sure if we did this we would not loose anymore rockets... :)

    Anyway.... I think all science should be conducted on a standard system. And for scientific purposes the metric is the far easiest.
  • The mixup happened when doing (or failing to do) conversions between english and metric units. In my experience, it's always been common to collectively refer these conversions (in either direction) as "metric conversions."

    I agree that a headline like "Unit mixup .." might have done just as well, but *I* personally saw no ambiguity between the headline and the story itself. I read "Metric mishap" and I immediately guessed (correctly) that someone goofed while doing a conversion.

    The point of a story headline is to state the topic of the article in such a way as to both interest the reader and to use as few words as is possible. I think the existing headline did that perfectly. I doubt most people will be reading it and thinking to themselves that the Metric units of measurment caused the spacecraft to be lost.

    If it *really* still bothers you, maybe you should write them a letter.
  • by DanaL ( 66515 )
    On behalf of Canada, I'd like to apologize for the metric system, although if I remember my history, it's really France's fault. Of course, Star Trek is also partly to blame :)

    Dana
  • What does 'english measurements' mean? Here in England, since metrication everything is in metres, kilograms, etc. As far as I know the only non-metric unit officially used is time. Do they mean imperial units? If so, surely that's American measurements - they seem the only people who are still using them.

    ...and wasn't the Mars Orbitor supposed to be an international effort????
  • by arthurs_sidekick ( 41708 ) on Thursday September 30, 1999 @10:31AM (#1646984) Homepage

    I wonder how much it costs companies who sell precision equipment to the US as well as to the rest of the world to maintain two bookkeeping systems? This particular incident is splashy, but there is no doubt a day-to-day cost of living a double measurement life that we never think of. Definitely, the US should convert; the argument was already there, this is just a nice incident to pin the argument on.

  • We could use all the Nukes we've got lying about! Then all living humas would be using the Imperial system and everything would be fine!

    A standard only works if everybody uses it (witness Microsoft and the broken DNS (twice now!)).

    Either everybody else goes Imperial system or we go metric system. 250 Million people to learn a new system v.s. 5.75 Billion. Hmm, that'll be a tough choice!

    One system is as good as another, as long as everybody uses it.

    On a side point, why in the HELL wasn't this caught in Quality Controll?!?

    /me GRUMBLES and goes back to trying to convert British BA thread forms to US SA threadforms for a simple metalworking project.
  • US and Britain should be apologizing to the world for American/English units. What the heck is a cord or a farthing or a slug or a hand or a yard?? Really ridiculous.
  • Well, as Roblimo said it - this is the occation to decide some standard on the area. Doesn't matter whether it's metric or English, but a standard i seriously needed!
  • Go back and read it again.

    Oh, whatever.
  • Agreed! We gotta deport Missouri, and fast! It's the only way to be sure.
  • Funny you should rise the issue of the Ryder Cup. The american audience

    a) Harassed the European players. Police had to remove audience at several holes before the play could continue.

    b) Rushed onto the field before the game was finished. It could still have been tied.

    If you consider that a win, sure. It says more about American sportsmanship than European skill at golf...
  • Sure, use measurements that make sense for what you're doing. An Electron-Volt is a super useful measure of energy when you're looking at elementary particles. It's the energy an electron gets after being accelerated through a 1 volt potential, something that makes more sense than a Joule (one Kg given a one Newton acceleration).

    But most of these very useful measurements are used in specialized areas that don't intersect much with other areas. You're not likely to measure the energy stored in a battery. Nor are you likely to measure your height in Au. On the rare occasions when you have to convert units from eV to J, or Au to m it's easy, one constant.

    The current "metric" system has lots of flaws, no doubt. Celcius doesn't have much meaning for scientific measurements, but makes a heckuva lot more sense than Farenheit for weather forcasts. At 0 water freezes, a very important weather number. At 100 water boils (another important weather number in perspective I suppose).

    The main flaw with the US Standard system is that it lacks any kind of self consistency. How many square inches are there in an acre? How many pounds of force are exerted by a one slug weight being accelerated at one foot per second squared?

    Where it makes sense to keep specialized units, fine, but I'll take my monitor size in cm, my car power in watts, and my height in cm. It takes a while to get used to using a different type of measurement but it's worth it.

    Isn't Slashdot the home to geeks who rebel against Microsoft? Microsoft's way of doing things is the familliar, comfortable, and completely *stupid* "Standard" way. Linux is the smart, not immediately intuitive, but *correct* "metric" way of doing things.

    As a quick side note though... Anybody have an idea when time will become metric? Sure days and years make great sense from an astronomical point of view, but months, weeks, hours, minutes, and seconds are all in these ugly multiples of 60, 24, 12, 7.... Ack. The conversion might not be too painful, afterall a minute is just 1.157 millidays...

  • by Eon78 ( 19599 )
    Hmm... I find this attitude very common under Americans. No personal offence, but the world consists of more than North-America. There's more out there, and they are using the metric system. So, this "bunch of foreigners" of yours happen to be the whole damn world population. You speak about the cost of moving to the metric system, but did you take into account the costs involved in *keeping* the imperial system? The tooling and equipment needed to convert between the two systems, etc. etc. costs huge ammounts of money each year again. Instead, if you go to the metric system you will have a one-time cost (which can be spread over multiple years of course), and after that... No more! Anyway, my 2cents... Grtz, Eon.
  • Hey, you know that driving on the right hand side is not really a standard. Japan and the rest of the commonweath drives on the left. :)

    Maybe they could change, but anyways, I'm not a brit. Thank you very much. :)
  • It's an idiom (albeit non-standard), and idioms always trump grammar. That idiom is particularly indicative of the dialect of a certain generation of Americans. Mister youse needn't be so spry concernin questions arty.
  • Do you realize you're a complete hypocrite? You sit there, claiming base 10 is evil and ickybad, yet there you are using arabic numerals, in a BASE 10 SYSTEM.

    So tell me, why are you doing all your math in base 10 and THEN converting to whatever godawful system you choose? To me, nothing could possibly make more sense then base 10. It's how we count. It's how many digits we (usually) have.

    How many inches to a mile? You'd spout some memorized value, but tell me, how easily can you count that out in your head? While if it's just base 10 metric, you move the damn decimal point. No memorization, only LOGIC.

    Personally, the metric system is the best thing to ever come out of France and we (almost) owe Napolean Bonaparte a pat on the back for it.
  • XVIII

    mr youse needn't be so spry
    concernin questions arty

    each has his tastes but as for i
    i likes a certain party

    gimme the he-man's solid bliss
    for youse ideas i'll match youse

    a pretty girl who naked is
    is worth a million statues

    - e. e. cummings
  • by Rational ( 1990 ) on Thursday September 30, 1999 @01:18PM (#1647005)
    It is much easier to imagine and understand what it means to say "I am six feet tall" than it is to say "I am one hundred and eighty three centimeters tall" or "I am one point eight meters tall".

    The hell you say. It may be easier for you because you have been raised used feet and inches, but there is definitely nothing intrinsically more intuitive about it.

    The Fahrenheit scale uses (aproximately) the normal human body temperature as 100. Since most real world temperatures (like weather) are done around this temperature and above 0 (the temperature of salted ice), the Fahrenheit scale is a more convenient scale for human life.

    Again, I take that you mean a more convenient scale for Americans. From my point of view, the Fahrenheit scale is a counterintuitive horror. After ten years of exposure to the Imperial system, I can deal with inches, miles, gallons and pounds, but I still can't get my head around Fahrenheit. Besides, the most significant transition point in "the real world" is that of liquid water to ice. The Celsius scale springs from this. How much more intuitive you want to get?

    I guess we all have our cultural biases and try to justify them, but from a standpoint of making sense, the Imperial System doesn't have much of a leg to stand on, definitely not in the 21st Century. Take my word (and that of all the other Europeans in /.) for it, the Metric system does work extraordinarily well in "everyday" situations.
  • by iserlohn ( 49556 ) on Thursday September 30, 1999 @01:19PM (#1647006) Homepage
    Hello?? This happened in England a few decades ago. The metric system was not in widespread use until the last few decades. If most of the world can do it, I'm sure Americans can too, unless they have a problem with the "not invented here" syndrome, which I believe they do.
  • You know, I don't buy the anti-conversion argument that it's "just not so simple to implement."

    I don't think most people realize just how far the metric system has penetrated, and how familiar we really are with Metric units. Americans seem *very* willing to buy soda in 2-liter bottles, to measure snow skis in centimeters, and everyone who has ever seen NYPD Blue knows what a kilo of coke looks like. Alomost every mechanic I know has a set of metric wrenches, because many cars require them.

    So the question isn't "Why haven't we switched to the Metric system?" The question is "Why are we using two systems simultaneously and not dumping the English system?"

    I think it would take about 2 seconds for people to determine if they were getting ripped off at the gas pump, and really, the issue of merchants using a Metric changeover as an opportunity for price gouging is irrelevant. People don't buy gas on the basis of whether they feel the price is *fair*. They buy gas where it's cheapest or most convenient. 31 cents a liter will be more appealing than 34 cents, just like $1.20/gallon sounds better than $1.25.

    And think of the excuses for speeding we would have: "Officer, I didn't realize I was doing 160 km/hr, because the km/hr numbers on my speedometer are so damn small!"

  • Of course! It's way easier to count in tens than in 12's. You'd have to memorize an incredible amount. It's more natural to count 5, 10, 15,
    instead of 6, 12, 18, 24, 32...??? And if you can't remember the units, just remember this:


    Keith (kilometer)
    Hit (hectare)
    Darren (decometer)
    Making (Meter)
    Darren (Decimeter)
    Cry (Centimeter)
    Mommy (Millimeter)

  • It's not as simple as that; aeronautics and aerospace traditionally use US/English units (because of the dominance of the US --and English-- aerospace industry). So, you get a lot of (older) engineers who can only think in English, plus a lot of look-up tables and software using metric (never mind aircraft instrumentation, etc).

    There was even a near-airccraft accident some years back because ground personnel filled up an airliner's fuel tank reading the gauges in gallons, while they were in liters.

    Unit conversion has always been a problem, something like this was bound to happen; that's why some of us write hacks in Javascript [malamas.com] (shameless plug ;-).

  • Canada did it in the 70's.
    I still weigh 195 pounds and am 6 foot 2. But the speed limits 110 on the highway and a liter of gas is 65 cents. But I need a cup of sugar and then I have to set the oven to 425 F.
    So you see this is what the metric world is like for the average joe.
    Yes it didn't/is not happening overnight, but you have to start somewhere.
  • 1 km = 1000 meters
    1000 meters = 100,000 centimeters
    100,000 centimeters = 1,000,000 millimeters

    1 mile = 5280 feet
    5280 feet = 63360 inches
    63360 inches ...

    Now I just wish they'd convert the time system to base 10.
  • From what I remember the Farienheit scale is based of off the tempature in London England, not any greater purpose.

    --
  • Metric units have much simpler relationships to each other, making many calculations much easier. This also makes it easier to understand, though that might not be immediately obvious to those who had to learn it AFTER already becoming familiar with imperial units. The difficulty comes from the tendency to try to understand the newly learned system in terms of the previously learned one. If we teach kids metric units first, this problem goes away, and the new generation will then immidiately recognize imperial units for the bizarre and unweildy system that it is when it comes time to learn about it (hopefully only for the sake of dealing with "legacy" technology).

    ---
    vilvoy
  • I said that because I know that they have no idea what metric measurements are. See I leave my car's LED displays to metric because I happen to use the metric system when I drive. and all three of them freak out when they look over and see how fast I am going.

    Try getting your 66 year old grandmother who has been managing a farm for 40 years to switch from acres to hectares and pounds to kilos.

    I wasn't being sexist...I was making a point. If the US switched to the metric system who is going to reeducate everyone.
  • by Anonymous Coward
    Pardon the paranoid rancor, but Do you you expect me to believe that we've lost another Hi-tech satelite that we sent to Mars... The last one just disappeared, now this one is headed toward the sun because our best minds blew chunks on measurement conventions?? Spare Me. Someone here has got to be drunk (unfortunately it aint me). maybe I could use that excuse when I pay my taxes and pay them in pesos. Makes you wonder why we can get this right....
  • No where NEAR the costs being spent to maintain two systems now.

    The only reason the US hasn't converted with the rest of the world was due to a stupid attempt to do it slowly (signs in both miles/km) the first time around.

    That, and the fact that they can afford to waste money calculating two systems of measurement, and have a strong enough internal market for many companies to skip converting all together.
  • Well people. That's very very funny. Knowing that
    a lot of that rocket stuff is made by the same Lockheed-Martin I would like to note a point when that stuff about Y2k comes up. Just to avoid errors from a certain UScentrism about the World.

    Please remember that Russia is located at GMT+3hours. Roughly New Year will appear here 8 hours before US. So if we shoot at 8 hours before
    New Year - it's our fault. If you do it at New Year then it's your fault.

    Now seriously. Lockheed-Martin is a very well known company with a huge experience in rocketry. They participated in several Mars missions. And they did much more than Mars. How such an error could go up with a company that possesses some of the closest ties with NASA?
  • Why do we use English instead of Metric? The same reason we use Microsoft Windows. The same reason your optic nerve is wired backwards. The same reason we ever get stuck with any other local optimum: the intermediate steps between here and there are worse than how things are right now. It doesn't matter how much better things could be, because greedy optimization algorithms have rule the world. 4 billion years of evolution have gotten us used to it.


    ---
    Have a Sloppy day!
  • I believe yout point of view depends completely on your personal experience. I'm a 20-year-old mechanical engineering student in a country which adopted the metric system almost at the time of my birth (C.R.). Therefore, I have used the metric system my whole life.

    Most of my college textbooks were written in the U.S., and I've had practice solving problems in both unit systems.

    The metric system does prove to be the perfect choice for scientific and technical needs, yet I don't think my life would be any easier if I had to think how tall I am using feet and inches, or translating ounces into pounds in a grocery store.

    Where in the world do people learn to multiply in base-twelve numbers (in the Western Hemisphere, at least)? How useful would twelve fingers be in a world where you add and multiply numbers using base-ten numbers?

    The point isn't really if the English system is better than the metric one; what's really important is that all systems used in a country should be compatible with each other. And since there's no place where you add in base-ten or base-twelve numbers, the metric system turns out to be *extremely* convenient ...

    Give it a try yourself ...
  • Boy we sure had a hot Thermidor this year didn't we?
  • by Anonymous Coward
    Well this argument is just as worthless as all the other arguments raised here. I personally can't see why a unit becomes more understandable if was based on someones foot a couple of hundred years ago or if it is based on the distance light travels during a very short but well defined time interval (which is the modern definition of what a metre is). And while we're discussing definitions I can point out that an inch (and most if not all other imperial units) is defined using the metric system. An inch for example is defined as 0.0254 metres (even in the US that is) and is thus exactly this. No matter what you say you cannot change the fact that today the inch is nothing but a weird fraction of a metre and still it is understandable for you: A weird fraction of the distance light travels during a weird fraction of a second. Perhaps simplicity in definition isn't all that essential after all.
  • My friend works at an airport for a rental car company, and one of there american customers complained to him that the metric system was stupid and backwards. to which he proceeded to tell her why it was a great system of mesurement, one base unit with prefixes attached depending on how much it is, everything base ten....
    I learned both metric and imperial in school, and to be honest with you, I have no idea how many feet there are in a mile, and how many pints in a hog's head(yes a real imperial mesurment) but I know metric awfully well.
    I am infact 198 cm tall and 78 kgs in weight. my car tops out at 135 (or so) km/h I drink 355ml cans of coke.
    My parents both grew up learning imperial. they know it pretty well. me, I know metric really well. start teaching metric only in your schools, within 20 years your country will have changed it's ways.
    vive la canada (and most of the rest of the world)

    metalgeek
  • by Anonymous Coward on Thursday September 30, 1999 @01:34PM (#1647036)
    I am amazed by the utter stupidity of your post.

    Don't you realize that all your pseudo-facts are completely biased by your education?

    The English system is focused on the idea that humans only want to / can deal with multiples of two or three things comfortably.
    Then metric wins, as there is only 1 "thing" to measure against, and 1 scale. Orthogonal design. Good.

    It is much easier to imagine and understand what it means to say "I am six feet tall" than it is to say "I am one hundred and eighty three centimeters tall" or "I am one point eight meters tall"
    Guess what I am 1m85cm tall and I "know" what 1m50cm tall means or 1m90cm tall. Why? because I have been raised in a metric country. 6ft. 1in doesn't mean anything to me.

    The English units of volumes are done in binary (and a couple, like tablespoons, in ternary). One foot equals twelve inches and one gross equals 144 objects because these are useful numbers: lots of other numbers divide them. Humans don't do floating point arithmatic with great ease. Use a system that bumps everything up into integers.
    Are metric-raised people superior then ? Because metric-raised handle non-integeral measures quit well, thank you. Ten has always been a stupid choice for the base of a number system.
    I would gladly agree with you but for a small detail: every day numbers are expressed in base 10, which makes handling a base-10 measurement system so much easier. Base 10 is drilled into everyone's mind since their kindergarten. SARCASM and yes base 60 is so much easier, no wonder it's so easy to teach children how to read a clock ! /SARCASM

    [Comparisonn of Fahrenheit versus Celsius]
    Again, you are biased by your upbringing. Metric-people have none of the problems that you attribute to the Celsius scale. And I boil water multiple times per week, I have a very good understanding of what 100C means. I have ice in my freezer and understand what 0C means. I certainly do not have a good perception of my body temperature, so 100K does not mean anything to me.

    t ranks right up there with the prostate as one of the fundamental ways in which humans are "designed". We should've been built with 12 fingers instead of 10. We'd all be much better off.
    Yeah right. We'd be better off without morons like you.

    Reality check: metric is as easy to use (or easier) as english. You are in denial because of your education, stop deluding yourself with BS explanations of why english is "superior" or "more natural".

  • It's not that simple: as an aerospace engineer, I have to excuse the NASA people somewhat: the US system is entrenched in the aerospace industry. Other fields may use 9.81m/s^2 exclusively, but for us 32ft/s^2 is as common, if not more. Add to that that for some numbers, US is more convenient (e.g., speed of sound ~1000ft/s) and, even worse, that most of the aircraft instrumentation is in US/English (because of the near total domination of the world aerospace industry) and things are even more screwed up.

    Having said that, I still think NASA should take a close look at their QA procs: this is not a new problem by any means...

  • Thank you all for pointing out my error.

    The metric pocket scale has divisions only down to 0.5mm, not 0.1 mm.

    Once again, thank you all for the lovely flames. My toast is properly browned.

    Phil
  • What's with this new-fangled XXIX?
    No one ever used subtraction in MY day.
    XXVIIII
    !
  • If we teach kids metrics first then they have no hope at learngin imperial units. Although Americans primarily use the Imperial Standard, most of us know BOTH!

    Poll: How many American on /. know both systems?
  • well france is as metric a country as you can be but when it comes to beer you can order a demi, which is half a pint, or a pinte which is a pint, or a ballon which is a quarter of pint aka 12.5 cl, which is a normal wine glass

    ---
  • Funny, in most of Europe the Imperial System has absolutely no place at all, and people manage pretty well...


  • I think that it's a grave error to ascribe to Napoleon the things that the French Revolution gave to culture.

    Not that I am all that fond of a system of units based on imposing an arbitrary modulo-10 scale to everything measured. Systems of measurement have evolved over centuries to scale well to the units being measured. Then a bunch of "radicals" come along and want to shoehorn it all into modulo-10.
    The ten month calendar was also a part of the grande plan. And the French started the count of years over again at zero. Why aren't the Metric geeks fighting for that as well?

    The "Metric system is the epitome of progress" crowd will never go away. There will always be people who insist that a system of units of measure is some marvelous thing. The best response is "get a life, loser."


  • So tell me, why are you doing all your math in base 10 and THEN converting to whatever godawful system you choose? To me, nothing could possibly make more sense then base 10. It's how we count. It's how many digits we (usually) have.

    The only reason base 10 (or A, if you prefer) makes sense is because we have 10 fingers. The reason we count in base ten stems from this fact from long ago. The number one-hundred makes sense to you as an obvious marking point, because this is the rollover to the 3rd digit, and all it is is 10^2. It's just as arbitrary as using 144 or 169, which would be 100 and 100 in base 12 and base 13 respectively.

    What the original poster was implying with base twelve is that you can easily divide things by two,three,four,and six. I heartily agree with this notion. That way, if you had a system where 1 bar equals 12 foo, a third of a bar is now 4 foo. Nice and simple. With base ten, one bar equals 10 foo, and a third of a bar is now 3.3333 foo, which gets tedious.

    Base sixty is especially nice, because things are now divisible by 2,3,5,6,10,12,15,20, and 30. Did I miss any? Talk about flexible! That's why it's so great that a circle has 360 degrees, it is divisible by so many numbers cleanly. I think this number stems from the Babylonian calendar, which had 360 days.

    In response to the gist of these systems, the English system, while ugly in many ways, does have some sense in that it's people-units. Ie, feet, hands. For a while I was a mechanic, and we used foot-pounds as units of torque. It's pretty cool, nice and quick I can get an estime that if I want to torque a lug nut to 90 foot-pounds, I can apply 90 pounds of force 1 foot down the wrench.

    Of course, it is horrible inconsistent in other respects as some things arre broken into 4, some into 12, some into 60, etc. If it were consistent, like 12 inches to the foot, twelve feet to the blah, twelve blahs to the blahblah, that would be better, but now it is approaching the metric system.

    Even the metric system is arbitrary, so they both their goods and bads. In general, people are not so easy to discard their old notions. A funny Simpson's quote is when the town is thinking of going metric, and grandpa simpson says, "my car gets 14 rods to the hogshead, and that's the way I likes it". And in a different one, Principal Skinner said he converted the new school clocks to metric time, and you see the clock with 10 divisions across the face. He said, "We're meeting at 89 minutes past 4 oclock" or something like that.

  • by dublin ( 31215 ) on Thursday September 30, 1999 @02:33PM (#1647063) Homepage
    It turns out that a thousandth of an inch is an extraorinarily usefully sized increment when dealing with machined parts. (Not to mention that when you need to check clearances, a one mil shim/feeler gauge is as close as the cellophane cigarrette wrapper from the nearest smoker - try it for yourself. No idea what thickness foreign cigarrette wrappers are, but I'd chortle if they're .001"!)

    By comparison, metric units tend to be either too large or too small: A millimeter is huge (39 thousandths), a tenth of a millimeter is still way too big (3.9 thousandths) but a hundredth of a millimeter is overkill at .39 thousandths, and makes accurate dial calipers, etc. more difficult and expensive. This also results in a unit that does not line up well with engineering notation, where exponents are multiples of three to help avoid errors - to fix this you either need to write .001" as .0254 mm or 25.4um (micrometers) - difficult because it's notoriously difficult to type the proper "mu" on non-greek keyboards, and micrometers are both little bitty and the device you use to measure small things with. On top of that, all of these folks "think" clearances and allowances in thousandths, their suppliers provide all their engineering information primarily in English units, and parts, tools, etc. are much more available (and cheaper) in English units than in Metric. Not to mention that everything they need to hook up to is English, so they can't just switch over.

    Most machinists and designers are proficient in both, but it's a pain. From what I've seen, the vast majority of US design engineers prefer to design in english and if the design has to go overseas for fabrication, they'll then convert and let the other guys deal with the horribly odd numbers that result.

    With computers to help us, there's no real reason to HAVE to change anymore. Seriously, it's still a hassle to convert, but it's much less trouble now than it used to be. Converting would be very expensive, cause many more NASA-type foul-ups, and offer little or nothing in return. It makes about as much sense for the US to convert to Metric units as it does for the rest of the world to adopt the English language. Sure, it makes things easier, but is it worth the trouble? And the cultural issues ARE similar.

    Finally, there's still a very real stigma attached to using the effete and wimpy Metric units in many US industries. I'll never forget the withering look I got a few years back when explaining to an oil tool executive that a gap was "about two millimeters" as he rejoindered, "MILLIMETERS? What the HELL?"

    FWIW, I think both systems are wrong and we should base length on "Dublins" (where the Dublin would be defined as the distance between a yard and a meter at which the acceleration due to earth's gravity is exactly 10 Dublins/s^2)! THAT would make life easier for a lot of people, and is easier than changing the second, which after all is perfect at 1/86400 of a day! [grin]

    Oh, and we'd have to build houses out of 5.08x10.16's (2x4's) that actually measure a nominal 4.445x8.890 (1.75x3.5)??
  • since first ordered by executive order--by President Jefferson.

    A little here, a little there. Things that have advantages convert. Things that don't might never convert--what real use is there for Celisius-speak about the temperature outside. Food is now beginning to come in metric sizes, as are some common parts. When new parts are designed, they'll usually be metric.

    OTOH, maybe this all just shows how dangerous shifting to that silly system is :) If we hadn't used some of them funny units, we'd still have the orbiter . . . [duck]

    Oh, and don't bother trying to sell me a car with a lot of cc's or liters of displacement--I want 400 cubes . . .
  • for using a *different* system than the Brits. U.S. liquid measure is only about .8 that of the corresponding imperial measures. This means that every time I order a pint, I get shorted by about 4 undersized/US ounces :)
  • Basically with the old money system (base 12) you could divide a bill for a meal between multiple numbers of people easily. with Metric Base 10 your are all left fighting over who ordered the extra rolls. :)

    This is a very real concern, and one of the reasons I prefer the US system; it makes explicit the notion that for everyday use people do not have the same measurement needs as for scientific use; and in fact that the two conflict. For everyday measurements, humans tend much more to think in terms of reference measurements and small multiples and divisors thereof. Like a half, a third, a fourth. When we need to think about big numbers of a unit, we convert into a mix of units anyway; there's good reason that nobody goes around saying that they're 74 inches tall---they'd say they're 6 foot 2, from which we mentally think ''two inches over six feet''. This may come as a slight surprise, but for someone who knows metric natively, if they're told someone is 179 centimeters tall, they don't think ''hmm, that's about... one, two... 179 cm. Ok.'' Rather, they think more along the lines of ''ok that's about 4 cm over 175 cm'', or ''1 cm below 180'' or whatever their own mental landmark is.

    The other big advantage lies not so much in the system itself as in how it's used. This is the ''better accuracy'' of the US system that you occasionally hear about; a misnomer, because metric could be used this way, it just isn't. That is, it's easier to specify my precision more precisely (got that?) if I say 3/8 or 15/32; with metric you've just got the millimetre. One could say two lines were 18 and 3/4 centimetres apart, which would implicitly mean "187.5 +- 1.25 mm"---yuck---but nobody does. They'll just say "187 mm" or "188 mm", nevermind that the lines themselves are each a millimeter wide; for scientists, it's fine to specify tolerances, but it's way cumbersome for everyday use.

    Overall, I have no fundamental objections to using the metric system units. They would swoop in and fill the various niches that the US system does; for small lengths there's the centimetre instead of the inch, for bigger lengths there's the metre instead of the foot and the yard. For really big lengths there's the kilometre instead of the mile. Major temperature swings will be fives of Celsius instead of tens of Fahrenheit. The litre will replace the cup, the pint, the quart, and the gallon. People would adapt to these new reference measurements easily. What I think is silly is the faux-precision most people seem to adopt when using metric... when I'm cooking, I dump a cup of water into the mix, and I'd be perfectly happy to dump a quarter-litre in; but it's ludicrous to talk about dumping "250 millilitres" (or even better, "237 millilitres") in, as if it would affect the recipe if I dumped in 249 or 252---as if I could or would even bother to measure it that precisely. It is this madness that I hope (futilely, I suppose) to avoid when and if the US ever converts to metric.

  • "So Bob, how many centimeters are there in an inch anyway?"

    "Geez, I don't know. 'round 3, I guess."

    "Okay then. 3 it is."

    :)
  • by SEE ( 7681 ) on Thursday September 30, 1999 @04:07PM (#1647102) Homepage
    Under Article I, section 8, the Congress has the authority to "fix the Standard of Weights and Measures." In 1866 the U.S. Congress passed a law establishing the legality of the metric system in the United States. (No other system of measurements has been established by the Congress.) We were one of the original 17 signatories to the Treaty of the Meter in 1875. In 1893, the metric measurement standards were adopted as the fundamental standards for length and mass in the United States. Congress passed the Metric Coversion Act in 1975. The Omnibus Trade and Competitiveness Act Of 1988 designated the metric system as the "preferred system of weights and measures for United States trade and commerce," and required that all federal agencies use the metric system by 1992.

    And it isn't a problem of corporations. GM and Ford both use metric (theoretically) exclusively internally. When gasoline companies tried to switch to liters, consumers rejected it. Multinational buisnesses have been major backers of metric conversion.

    So, given that we are already legally metric, how are we going to do this 2-5 year conversion you speak of? Six months in jail for small buisnessmen using Customary units? $100 fine per incident of civilians calling themselves 5'10"? Life imprisonment without parole for tecahing you child ounce-to-pound conversions?
  • Don't forget that while it is true that SCIENTISTS use the metric system in R&D...
    Please don't forget the rest of the world... ;)

    Seriously, I think it's not impossible at all to do the conversion, even in the US. It has happened before, in all times. The metric system didn't spread around the world in a night. Everywhere where there has been a change in measurements there have been protests. Loud, painful, and even sometimes riots.

    But it always gets to the point where people start getting used to it. When they realize that it hasn't changed the world around them (physically), that using the new measurements work, and most important of all, they get a grip of how much the new measurements are, the complaints from ordinary people about the change will disappear.
    When the average person understands that he is 175 cm tall and hence can get some clue about other heights in the metric system from that, and that his car can speed up to 210 km/h, and that other cars that are slower than his would speed up to some speed lower than that, he would begin to understand. It's all about people getting a grip of what the common limits, measurements and distances they use in their everyday life look like in the metric system. Once they've come to that point, the translation goes much quicker.

    A (good?) proposal would hence to make people get cheap, simple translation/conversion utilities, so that they can start getting familiar with metric values, and at the same time enforce the use of metric systems in law.
    The thing about conversion utilities is happening in many European countries as we speak. We have to get used to a new currency, the Euro, and even before people have their new money in their hands they can measure what their salary would be and what that bottle of cola would cost.

    I don't think the "learning" of metric systems in school would be necessary to make the conversion possible. That would just mean that the US should have to wait 70 years or something like that from now before a conversion, when all of the population has learned the metric system from school... Such a time perspective is rediciolus, if you ask me.
    A change would have to be quick and as painless as possible. A "smooth" transition, where both systems would cooexist just causes pain, frustration and accidents like the above mentioned, just more commonly and in everyday life and in every situation, for a long period of time. Surely a quick conversion would also cause pain, but I'd prefer the quicker pain... ;)

    It could take years or decades for people to get used to a new measurement system in every aspect in the world around them, but I think that it sure would be worth it.
    Help people getting used to the new system by giving them tools for conversion (or sell them cheap). Start conversion of public systems, regulations, declarations, government information and so on. It has to start with a law. I know that most Americans hate laws and regulations, but sorry folks, some things has to start with a law so that they can ever happen, and I think that this is definately such a thing.

    So start it! Can't we use a global Slashdot effect to convince the US politicians? ;-)

  • The problem is really social, not legal. The legal US weights and measures definitions are metric, and have been for many years. Officialy, the foot is defined in centimeters. (In fact, there is an international foot and a US foot, that are very, very slightly different in length) This is mostly due to a variety of treaties on measurement, trade standards and the like that we are a party to.

    The problem is that we have been able to choose as a society not to change to SI in everyday measurement, because we are not only a huge market, but the world's dominant market -- we can force producers in other countries to acccomodate our own crochets, like preferring gallons and feet and pounds. There is no political consensus at this point on legally forcing conversion of everyday measurement to be SI only, and there will not be until there is some sort of social or economic crisis that forces most Americans, or at least American business leaders, to want it.

  • by Mr. Theorem ( 33952 ) on Thursday September 30, 1999 @03:06PM (#1647141)
    There's been a lot of talk here about scientists using the metric system--that's only sort of true. At least in physics, there are those who insist on SI units (Systeme International, e.g. meter,kilogram,Kelvin), some who hang on to CGS (centimeter,gram) units, and a bunch of other unrelated units that are incredibly useful.

    What is called the metric system seems to mash together the SI and CGS units, plus the celsius temperature scale and the use of liters for volume. In order to get the easy conversions to work right, you have to stick to either CGS or SI else powers of ten end up missing. The celsius scale (my least favorite of the metric units), by the way, doesn't give any of the easy conversion advantages that the rest of the metric units has; its thermodynamically irrelevant. The celsius scale doesn't work for equations (e.g. PV=nRT) involving temperature. The SI unit of temperature, of course, is the Kelvin.

    I'm not aware of any weather forecasts, anywhere, that use Kelvin. I also think kilowatt-hour is in widespread use worldwide for electric power, even though Joule would be the strict SI unit. Likewise kilometers per hour instead of meters per second.

    Units really get hairy in electrodynamics. Experimental physicists work with SI units almost exclusively, as that's what lab equipment is made in. Except that magnetic fields are sometimes measured in gauss instead of Tesla. Theorists, on the other hand, often use CGS because the calculations are more elegant. But everyone uses liter, even though its not really SI.

    Torr, the unit of pressure, is still in widespread use (1 torr = 1 mm of mercury), although bar and millibar are creeping in. Angstroms are in widespread use and likely always will be.

    Physicists would be lost without the electron volt (1eV=1.602e-19 Joule). Atomic mass units (amu), astronomical units (au=Earth-sun distance), light-years, and parsecs are similarly very useful and in widespread use. Furthermore, if you look at graphs in physics articles, you'll often find the raw quantities multiplied or divided by constants such as the Bohr magneton, Planck's constant, or the Boltzmann constant.

    By far the most useful way to state the speed of light is one foot per nanosecond. Likewise, the speed of sound in air is roughly one foot per millisecond.

    The choice between Kelvin and Celsius is mostly a matter of convenience. Chemists use Celsius almost exclusively, physicists--especially those working at low temperatures or with thermodynamics--use Kelvin.

    The point of all this is that practicing scientists use units that are appropriate to the problem. I think we should be comfortable in a variety of units and be able to convert when necessary. I'm perfectly happy with camera lenses in millimeters, monitors in inches, the weather in Farenheit, my experiment in Kelvin, cars in horsepower, light bulbs in watts, and everything else in units that makes the quantity measured easier to think about.


  • http://nodis.hq.nasa.gov/Library/Directives/NASA -WIDE/Policies/Program_Management/N_PD_801 0_2B.html
  • In any school I've been to or heard of, this was punishable by death (well, not quite, but you'd look pretty dumb).

    I never even *thought* of leaving out a unit. That way lies madness...
  • While I don't take the blame personally :-), I think a lot of the problem with the metric conversion is the chemical industry, and specifically the petroleum one. Chemical engineering students still need to learn both systems, as *MODERN* textbooks still teach both and give problems in both. Since much of the rest of the industry in the US is dependant on chemicals, this is probably a result from that.

    We've tried to switch, but it's realllly hard. Too many of the empirical equations that we use are based on english units, and while not impossible to switch, no one wants to rework these out.

  • by Darksky ( 58431 ) on Thursday September 30, 1999 @10:35AM (#1647211)
    .... these people aren't exactly Rocket Scientists after all..... oh, wait...nevermind....
  • My physics teachers always used to fail me on my assignments, many years ago, unless I explicitly stated the units in all my caculations...
    Hmmm...
    Guess they had different physics teachers..

    Malk
  • should be the universal system of choice but there are cultural problems in America that keep us from moving to metric. Most of it has to do with old ideas of individualism. People want to be individualistic yet want to communicate with the rest of the world. Scientific measurements cant besome roll your own system used exclusively in your country, come on NASA get with it.
  • One problem with the Imperial system is that the inch is the smallest unit of length. Once you go smaller than the inch, there's no true standard about how to subdivide the inch. An Imperial socket set is probably calibrated in 1/32 inch steps. The standard separation in computer parts is 1/10 inch - for example, TTL chips. Printers print out documents with 1/300 inch precision (300 dpi). With Metric, there's a firm standard about subdividing the unit.

    One contributor has pointed out that Metric uses multiples of ten, and not many numbers divide into 10 easily. One uses Metric to measure things, not to divide numbers. I prefer to remember multiples of 10 rather than the seemingly random measures of the Imperial system. The numbers 2, 3, 4, 5+1/2, 8, 12, 14 and 20 all find a home in some Imperial units: 2 pints = 1 quart, 3 feet = 1 yard, 4 quarts = 1 gallon, 5+1/2 yards = 1 rod/pole/perch, 8 furlongs = 1 mile, 12 inches = 1 foot, 14 pounds = 1 stone, 20 fluid ounces = 1 U.S. pint.

    Americans, who were one of the first countries to use a decimal currency system and who have successfully attempted some spelling reform of the English language, should have little trouble adapting to the Metric system when it is eventually introduced. If Americans wish to "go Metric" in the future, I would advise them to study how Metric was introduced in other countries to see what methods worked and what didn't.

    If I could change one thing in the world, I would make the inch equal 25.6 millimetres instead of 25.4 millimetres. Then:
    1/2 inch would be 12.8 mm
    1/4 inch would be 6.4 mm
    1/8 inch would be 3.2 mm
    1/16 inch would be 1.6 mm
    1/32 inch would be 0.8 mm
    and so forth. One wouldn't need to buy a new set of wrenches then!
  • Base sixty is especially nice, because things are now divisible by 2,3,5,6,10,12,15,20, and 30. Did I miss any? Talk about flexible! That's why it's so great that a circle has 360 degrees, it is divisible by so many numbers cleanly. I think this number stems from the Babylonian calendar, which had 360 days.

    Why not switch to base 360 then, and get even more flexibility? Never mind that it's hard to find 60 unused and visually distinctive symbols which are easy to read and write, and that it's harder to mentally perform arithmetic in base 60 than base 10.

    The best, then, would be base infinity. It would be divisible by anything, and it would greatly simplify calculus. :)

  • While for most purposes I agree that the Celsius system is superior, for weather the Fahrenheit system still seems better. It allows people to say things such as "the weather is in the 90s today" and people know what you mean. In Celsius you'd have to say "the weather is in the mid 30s" or something, since 30 and 40 are certainly not what you're referring to.

    With some practice I suppose it isn't that bad, but the greater precision of the Fahrenheit units (1.8 degrees Fahrenheit for every degree Celsius) makes smaller changes easier to understand.
  • I'm not at all surprised by this. Well, maybe I am afterall.

    The scientific community all over the world works primarily in metric units. Why that isn't the standard as a matter of policy is a mystery to me. As it is now, if you're talking gallons you have to specify U.S. gallons vs. Imperial gallons. Sure, the inch is defined by an act of Congress to be exactly 2.54cm. That doesn't take away the fact that the U.S. in general has clung to it's use of statute miles, and other odd measurement systems for all the wrong reasons.

    The historic reasons for use of these systems no longer serves it's purpose. Reasoning that Americans will have difficulty converting is an additional load of "hooey."

    After a 2 to 5 year transition period passes the use of metric measurements by the general populace will be second nature. Conversion of food and other material measurements will be a cost savings for goods producers as well. There are real costs related to labelling in multiple scales.

    The computing industry has shown time and again... Standards Are Good! Use them and be happy.

    D. Keith Higgs
    CWRU. Kelvin Smith Library

  • I noticed this the hard way a few years back when I bought an Alfa Romeo 164S (awesome) that had a digital climate control, switchable from english to metric.

    It became obvious fairly quickly that switching to "F" just twiddled the display, and the thing was still using Celsius to decide what to do. This is a big problem, because Celsius degrees are just simply too big to use for controlling the temperature if human comfort is what you're after. (Each Celsius degree is nearly twice as large (9/5, actually) as each Fahrenheit degree.)

    It does seem that many "foreign" thermostats use Celsius degrees, giving them about half the resolution of American thermostats... Still, if I could buy a new Alfa here, I would - I loved that car!
  • Pretty much everything related to space and orbital mechanics is done in the metric system. Especially when working with any international project.

    Time for the U.S. congress to outlaw using any non-american system, and to limit the export of any strong measurement system. :-)

    Really, it will be interesting to see who finally gets the blame, other than the obvious hand waving and blame sharing. Final result will be a big report with no one team to blame, just a recommendation to increase the funding of the review process.

    the AC
  • Pull something 1 Meter with the force of 1 Newton in one second. Now you've done the work of 1 Joule with the power of 1 Watt.

    And now do this with feet, pond, calories or whatever...

  • In the UK we refer to English units as Imperial units. While they have the same names as the US versions, the sizes are slightly different.
    (e.g. our pint is 20 fl oz, not 16, our ton is 2240 lb).

    Imperial measurements were abandoned by schools during the 70's when I was a child. However, they are only now being phased out in retail: it was only a couple of years back when meat started to be sold by the kg rather than the lb.

    People still talk about a pint of milk, although it is almost always a 1/2 litre. There are some bizarre mixtures: fabric comes in 45 or 60 inch widths, but is now often priced by the meter lengthways.

    Most nuts and bolts, and also spanners, are now metric, although a full toolkit still comes with both - a bit of a waste I guess.

    In my scientific work I use the electron as a unit of charge and the angstrom as a unit of distance.

    The unix `units' program is always handy if you need to convert forces from hundredweight furlongs per fornight squared into something useful.
  • by runswithd6s ( 65165 ) on Thursday September 30, 1999 @10:43AM (#1647325) Homepage
    And if this event doesn't prove that it's time for the U.S. to go 100% metric, I don't know what will. Oy!

    This statement is all right and good except that it is a bit naive. Although the US is non-standard by following it's own measurement systems for lenght, volume, and weight, it is not necessarily bad. Ask just about any professional machinist what measurement system (s)he uses and you'll find more often than not that they use the US "Standard" system over the Metric. A machinst friend of mine claimed, "it's more accurate." Now, as someone acquainted with the more complicated mathematics, I understand measurement systems as nothing more than numbers. Accuracy in and of itself does not lie in the system used to express the measurement. Speaking practically, however, it seems that the US has found its niches. Its not surprising either, we've had a couple hundred years to get used to it.

    As a scientist, I realize that the US mesurement system is not used in all aspects of life in the US. Step into any chemist's lab and you'll find beakers labled liters and milliliters. You'll find scales labeled Kilograms, grams, and micrograms. Factors of 10 are convenient indeed when it comes to science.

    Hey, I'm all for such a conversion, but such a conversion would never be 100%; at least not for quite a few years. Just think about how the less honest business "entrepeneaurs" would take advantage of the mass confusion caused by such a conversion. Gas would be sold in liters instead of gallons, a two or ten cent raise in price per liter may go unnoticed (initially). Everything would be thrown out of context for US residents. Every industry would be impacted. For the price of conversion, the rewards would be ill received.

    Yes, it's simple to say that the US should convert to metric, just not so simple to implement.

  • by Eccles ( 932 )
    >So where are we going to get all the money to go metric?

    Acutally, there's a very easy way to convince Americans to go metric. First, as a convenience, set up metric equivalents that are similar to Imperial units. A metric "inch" is 2.5 cm (2.54 is too many digits). A metric pound is 0.5 kg. Most of us already know liters from 2 liter bottles. The handy thing about doing this is that with these "metric inches" and "metric pounds", everyone would be an inch or two taller and ~10% lighter! That alone should sell the conversion...
  • While we're reminding the Americans that their measurements are non-standard.

    Americans - STOP USING NON-STANDARD PAPER NOW
    Everybody else on the planet is using a paper standard that
    - Looks nicer (A4 ratio is pleasing to the eye)
    - Has an ISO standard
    - Scales nicely (envelopes to posters in one simple standard)
    - Just Works (TM)

    Please catch up to the 20th century and next time buy A4. Government studies show you'll SAVE money too!
  • It turns out that a thousandth of an inch is an extraorinarily usefully sized increment when dealing with machined parts.

    Only becuase that's what you are used to dealing with. .01 mm would be just as usefull (if not more so) than .001 inch.

    This also results in a unit that does not line up well with engineering notation, where exponents are multiples of three to help avoid errors - to fix this you either need to write .001" as .0254 mm or 25.4um (micrometers)

    Your only problem is trying to convert. Start with .025 mm and you have no problem. Quit trying to use "round" imperial measurements in metric and use "round" metric measurements instead.

    Oh, and we'd have to build houses out of 5.08x10.16's (2x4's) that actually measure a nominal 4.445x8.890 (1.75x3.5)??

    No, you'd built it out of 5 x 10s (nominal 4.5 x 9). Convert that to imperial...

    The only thing that keeps Americans from adopting metric measurments is arrogance (i.e. not-invented-here syndrome).

  • Although the US is non-standard by following it's own measurement systems for lenght, volume, and weight, it is not necessarily bad. Ask just about any professional machinist what measurement system (s)he uses and you'll find more often than not that they use the US "Standard" system over the Metric.

    Well, in the US perhaps. The other thing you might want to consider is the impact of building stuff to US/Imperial standard on your export markets: I used to work as a blast hole driller in the mines in Aust. & the company I worked for chose to place a half-million US$ order of drills with a Japanese company over a US company. There wasn't much between the two types of drill except that the Japanese ones were all in metric (bolt sizes, shaft sizes etc) and the US ones were all in US/Imperial. While we're used to working on machines built to both standards, our metric toolboxes are a hell of a lot better equipped, & it was enough of an issue on an otherwise close bid to decide who got the contract.
  • Oh, that's fine, change us over to metric, then we'll just have to change again when the 12-fingered aliens take over.

    "The number of suckers born each minute doubles every 18 months."
  • by M@T ( 10268 )
    the Fahrenheit scale is a more convenient scale for human life.

    Next you'll be telling us that it makes more sense to drive on the right side of the road as opposed to the left.

    To me, living downunder, 40 degrees means its fuckin' hot, below 0 means its fuckin' cold, and 300 kph is fuckin' fast.

    On the other hand, I know that 100 F is hot, but I don't know how hot... I know that 30 F is cold, bu I don't know how cold, and I know that 300 mph is really fucking fast but unless I convert it to kmh I can't really appreciate it.

    It all comes down to what you're used to.

    M@T
  • This has the classic look of disjointed process management. It doesn't really matter which system was used, rather that they weren't consistent. The blame here goes to the project management, not the engineering teams. A reasonable (IMHO) guess here is that each team produced what they were asked, complete with solid QA work, but little or no integration testing was done.

    And I always thought project managers were a joke .....

  • Obviously the decline and fall of the American way of life can be tracked to the insiduous creeping sway of the metric system. Consider our history...

    1898--Teddy Roosevelt and the Rough Riders storm San Juan Hill in the penultimate act of the War with Spain. A victory over a metric-impaired army! Afterwards, the troops celebrate with gallons of beer and quarts of whiskey.

    1918--The end of the Great War. The USA comes to the aid of the Old World, which got itself into trouble because of their metric leadings. It seems the French troops couldn't load their 7.62 mm rifles because everybody was expecting to receive 7 or 8 mm bullets. Troops from "over there" save the day with .30 caliber bullets (clearly, rounding to inch form is superior here!).

    1969--US technology triumphs with a manned landing on the moon! No metric-loving country can claim that, esp. those Russkies. After all, the astronauts only had to go 25,000 mph to get to escape velocity, while the metric nations had to get to 40,000,000 meters per hour. Since everybody knows that 25000 early 70s--USA starts promoting metric system

    later--Richard Nixon forced to resign

    late 70s--Pascal invented

    80s--SF 49ers win Super Bowls

    80s--space shuttle explodes. Rumors are it was built using metric system.

    90s--liquor sold in easy to factor 500 ml and 1750 ml containers, leading to street gangs and cocaine use.

    You see, when we were purely metric and we had four dozen stars on the flag, life was swell. But as soon as that metric stuff crept in, such as those 50 stars, life went downhill.

    The solution, in my view, is obvious...

  • Well then convert =)

    60 F is around 15.5 C. Not cold, but somewhat chilly.

    I personally can get along pretty well in both systems, since I live in the US and have spent quite a bit of time in Greece. I still don't like Celcius's lower precision, since having to use half a degree (i.e., saying it's 16.5 out) is more annoying than using smaller degrees and sticking with integers (like Fahrenheit does).
  • That's just the latest round. We've been deciding to go metric and then not doing anything about it for nearly 200 years now :)

  • Close. The chevy 400 was also listed as 6.6 liters. But 6600 or 6.6 just doesn't have the ring of 400 (which is close to the horsepower it put out before the replaced the 4-barrel with a 2-barrel over emissions).

    I had one in a 72 Impala -- three tons of American steel, 400 cubes, and 12 miles to the gallon (properly tuned, and on the highway). Sucked gas, but what a ride . . .
  • by / ( 33804 ) on Thursday September 30, 1999 @11:23AM (#1647505)
    The English system is focused on the idea that humans only want to / can deal with multiples of two or three things comfortably. Therefore, each class of jobs gets its own particular unit of measurement. It's one philosophy, and it's the one that ultimately wins out with human nature. It is much easier to imagine and understand what it means to say "I am six feet tall" than it is to say "I am one hundred and eighty three centimeters tall" or "I am one point eight meters tall". Combine that with the fact that most people misuse kilograms as a unit of force, and we're all better off using pounds or stones anyway.

    The English units of volumes are done in binary (and a couple, like tablespoons, in ternary). One foot equals twelve inches and one gross equals 144 objects because these are useful numbers: lots of other numbers divide them. Humans don't do floating point arithmatic with great ease. Use a system that bumps everything up into integers.

    Ten has always been a stupid choice for the base of a number system. The Babylonians had a much better idea with base 60; look at all the numbers that evenly divide into 60 (and look at our system of time and try to think whether it would be better if we only had 10 "hours" in the day instead of 24 or 100 "minutes" instead of 60.

    The convenient thing about the metric system is that it is focused on the idea of orders of magnitude, and since lots of science is also concerned with orders of magnitude, that makes the metric system appropriate for scientific applications. The problem with using the metric system in our normal daily existence is that most humans only have to deal with one or maybe two orders of magnitude as they go about their day. For the few instances where that stops being true, using a different system of units wouldn't kill anyone.

    Why does the celsius scale define 100 to be the boiling point of water at one atmosphere? Because it's a convenient constant and lots of laboratory conditions are done near that temperature. But notice how it's done in terms of 1 atm and not 1000 pascals or some such power of 10. There exist these fundamental constants in nature, and lots of them don't have anything to do with each other. Yes we can measure charges in units of coulombs, but since most of nature is constructed in multiples of the electron charge, you still have factors of 1.6x10^-19 in your equations. You're not eliminating complexity; you're just pushing it around. No system of units will eliminate all of this kind of complexity. You might as well use units that are convenient for humans.

    The Fahrenheit scale uses (aproximately) the normal human body temperature as 100. Since most real world temperatures (like weather) are done around this temperature and above 0 (the temperature of salted ice), the Fahrenheit scale is a more convenient scale for human life. An analogy: it's like the differene between using an analog car speedometer that goes between 0 and 85 or one that goes between 0 and 140 mph. Since most of your driving is done between 0 and 60, and rarely if ever above 80, all that part of the scale above 80 is just wasted and it squeezes the part we care about into a smaller space that complicates interpolation and other visual interpretation of the value displayed.

    It ranks right up there with the prostate as one of the fundamental ways in which humans are "designed". We should've been built with 12 fingers instead of 10. We'd all be much better off.
  • Don't forget that while it is true that SCIENTISTS use the metric system in R&D, NASA is NOT a scientific/R&D organization, they are primarily an engineering and development organization that supplies services for a lot of R&D. The fact is that most engineers working in the US (especially those over 40) have been trained primarily in the ENGLISH system of units. Most of the engineering fields are now a mess because the science half of the picture is in metric, but when the engineers have to translate their work to the 'real world' a conversion to english units must be made so the shop floor guy or assembly tech or manufacturing plant will understand what is going on.

    Unfortunately government mandated conversion to the metric system has flopped at least twice partly because of inertia, and partly because Americans don't like to do what the government tells them to. There have also been riots and protests against adopting something the 'Godless French' invented (see Martin Gardner for some interesting histories here).

    It would be nice to have a mass conversion to metric, and it would solve a lot of problems (but not all - ever try to use Japanese metric bolts on a French bicycle????) but I don't see it happen until we get teh schools teaching only metric. And we can't even get them to teach evolution.

  • This is sad and funny at the same time, I guess.

    Here's a particularly interesting quote:

    "People sometimes make errors," said Dr. Edward Weiler, NASA's Associate Administrator for Space Science. "The problem here was not the error, it was the failure of NASA's systems engineering, and the checks and balances in our processes to detect the error. That's why we lost the spacecraft."

    Ok, this is a reasonable tone for a public statement. I just have to imagine the tone at the moment of discovery when their internal review uncovered this:

    "WHAT!!! Do you have any idea how this is going to make us look!!?? We are going to be the laughing-stock of the scientific community over this! MY GOD! Get me the head of the dumbass who's idea it was to use inches feet and yards to compute the %^&@$# trajectory of an interplanetary vehicle!"

    Man, I wouldn't want what's left of _that_ guy's career!

  • The whole Metric vs. English measurement is really bogus. The obvious issue here was that there was poor communications between JPL and their contractor.

    I mean, even if the measurements were in the correct measurement system, without clear communications, you won't know exactly what the hell they are for. If JPL did not know for a fact that the numbers they were pushing into their system were the correct data, *including* the units of measurement, then they have no excuse for allowing that data into their system.

    Obviously, they need better ways of communicating information with their contractors, including bundling of the measurement system, and some sort of failsafe test that would prove that the numbers they entered were correct.

    Otherwise, even if you stipulate that everything sent to you be in metric, you still may screw up when someone submits something in mm when you expected cm.

  • []
    > By comparison, metric units tend to be either too large or too small:

    That's funny: I've never heard someone complain about the metric system here in France with units being either too small or too large. And no, I don't think that it is because it was invented here.

    The only reason of your problem is that you are not used to the metrical system, that's why you feel it is "unnatural", trust me I don't have at all this problem.

    > With computers to help us, there's no real reason to HAVE to change anymore.

    It is not a computer problem but a human problem... What do you think ? That at the NASA, they don't use computers.

    > Converting would be very expensive, cause many more NASA-type foul-ups, and offer little or nothing in return.

    Any change is painful, but after the change is completed, it would prevent this kind of error.

    > It makes about as much sense for the US to convert to Metric units as it does for the rest of the world to adopt the English language.

    A language is different from a metric system, it is easier to change the metric system that the whole language, and BTW what is the language I'm typing in right now ? Esperanto ? No, it's English so in a way the rest of the world IS adopting English.

    I don't claim at all, that the metric system is the perfect system, but if look at it without the NIH syndrome, it is quite coherent, and useful. (me i would like to have a system in which the speed of light is 1 :-)

    Oh, BTW I do remenber another mistake from the NASA when they used terrestrial miles instead of nautical miles (or vice versa) while they were trying to rescue a spaceship...

    In Europe, we are on the verge of changing of currency unit, it won't be easy to adjust to the Euro, but it'm not too worried. The US could change its unit system if there was a real will.
  • Just because it's old doesn't mean it's bad. :)

    Actually I recall a really old news story written around the time Englands Currency changed (1969/1970) about how Metric would work out worse for people.

    Basically with the old money system (base 12) you could divide a bill for a meal between multiple numbers of people easily. with Metric Base 10 your are all left fighting over who ordered the extra rolls. :)

    Think the system was based on your fingers, but you can count in base 12 (or base 13) on your fingers if you use the three parts of each finger as one unit. If we had an extra finger we could do base 16 :)

    Personally I prefer Hex.

  • Maybe I should clarify what I meant by "too large or too small": .001" is an increment that can be readily easily measured with reasonably inexpensive instruments. Halving that makes them far more expensive.

    As pointed out in other posts here, the same problem applies at a larger scale (ugh) when dealing with machinist's rules and scales: You can easily purchase scales with a resolution of .01", but a tenth of a millimeter is impractical, as the hash marks are too close together, which is why the most accurate metric scales commonly available have only .5 mm resolution.

    The limit is one of cost effectiveness and human perception. For this purpose, english units are superior on a small scale such as this. Obviously, it doesn't make any real difference which you use, but one can legitimately be easier and more useful than another in a particular situation. (And there are instances in which metric units are clearly easier and more useful...)
  • Well, for the "horribly odd numbers" problem, there is a simple answer. You start out thinking in inches and determine (for example) that a clearance of 0.001" is about right, and this then gets translated to the cumbersome 0.0254mm. Had you been thinking in metric, the clearance would have been 0.025mm (or even 0.03mm or 0.02mm), and the number mess would have appeared when translating to american units instead. The amreican unit system isn't more or less "natural" than the metric system -- things in nature do not tend to fall into simple increments of inches. It's just us fallible humans that like to appoximate things so it becomes convenient for ourselves.

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