What an absolute unit
February 19, 2024 12:14 PM Subscribe
On its maiden voyage in 1628, the Vasa warship capsized and sank. Originally thought to be caused by too many cannons on too many decks, one of the leading theories now is that shipbuilders used different rulers. Four were found in the wreckage, two calibrated with the Swedish Foot and the other two rulers used the Amsterdam Foot. Not only are they different lengths (29.69 cm versus 28.31 cm), the Dutch Foot was divided into 11 instead of 12 inches. These errors multiplied over the size of the ship led to lopsided construction and potentially the inevitable sinking.
A few hundred years later, the Mars Climate Orbiter mixed up metric and imperial leading to the loss of the space craft as it failed to aerobrake in the Martian atmosphere. The Gimli Glider is another imperial/metric confusion: a Boeing 767 refueled with pounds of jet fuel that were entered into the computer as kilograms, causing fuel exhaustion while between Montreal to Edmonton.
To the best of my knowledge, no problems have yet been caused by the 648 second difference between a Julian and Gregorian Light-year. The minor discrepancy means the two differ by around two hundred million kilometers, or roughly half the distance between the Earth and Mars.
A few hundred years later, the Mars Climate Orbiter mixed up metric and imperial leading to the loss of the space craft as it failed to aerobrake in the Martian atmosphere. The Gimli Glider is another imperial/metric confusion: a Boeing 767 refueled with pounds of jet fuel that were entered into the computer as kilograms, causing fuel exhaustion while between Montreal to Edmonton.
To the best of my knowledge, no problems have yet been caused by the 648 second difference between a Julian and Gregorian Light-year. The minor discrepancy means the two differ by around two hundred million kilometers, or roughly half the distance between the Earth and Mars.
If true, this is a rather remarkable precursor of the 19th century measurement error that led to Swedish three-foot gauge railways due to a confusion of Swedish and Imperial inch and foot units. The Vasa ship is worth a visit should you ever have a spare afternoon in Stockholm. I understand that the museum may need some major renovations in the coming years, to replace the steel cradle the boat rests in.
I have a funny find from a Swedish flea market, which is a late 19th century folding ruler with four different measurement units on its four edges: Imperial inches ("London"), Swedish inches, metric, and Swedish "decimal inches", a short-lived measurement unit that divided a foot into ten inches, each divisible into tenths.
posted by St. Oops at 12:34 PM on February 19 [10 favorites]
I have a funny find from a Swedish flea market, which is a late 19th century folding ruler with four different measurement units on its four edges: Imperial inches ("London"), Swedish inches, metric, and Swedish "decimal inches", a short-lived measurement unit that divided a foot into ten inches, each divisible into tenths.
posted by St. Oops at 12:34 PM on February 19 [10 favorites]
From the Amsterdam Foot link: The voet ("foot") was of the same order of magnitude as the English foot (30.48 cm), but its exact size varied from city to city and from province to province. There were 10, 11, 12 or 13 duimen (inches) in a voet, depending on the city's local regulations.
One can debate the merits of having 10 units in a measure versus 12 (e.g. the convenience of base-10 numbering vs 12's many divisors), but it takes a special kind of madness to use a prime number of units, much less a different prime number from another town just down the river.
But it gets worse! The Amsterdam voet had 11 duimen, but there were 13 voeten to the roede. 143 duimen to the roede, what could be simpler??
It's too bad the system is long obsolete, or else the US could have an even less rational system to look down on.
posted by jedicus at 12:36 PM on February 19 [23 favorites]
One can debate the merits of having 10 units in a measure versus 12 (e.g. the convenience of base-10 numbering vs 12's many divisors), but it takes a special kind of madness to use a prime number of units, much less a different prime number from another town just down the river.
But it gets worse! The Amsterdam voet had 11 duimen, but there were 13 voeten to the roede. 143 duimen to the roede, what could be simpler??
It's too bad the system is long obsolete, or else the US could have an even less rational system to look down on.
posted by jedicus at 12:36 PM on February 19 [23 favorites]
jedicus: "the US could have an even less rational system to look down on."
Take heart. The US has both the "international foot" and the "survey foot"; the two differ by 2 parts per million.
posted by adamrice at 12:49 PM on February 19 [7 favorites]
Take heart. The US has both the "international foot" and the "survey foot"; the two differ by 2 parts per million.
posted by adamrice at 12:49 PM on February 19 [7 favorites]
I am absolutely delighted to hear that there is another theory as to why the Vasa sank rather the weight of the guns (if you ever find yourselves in the vicinity, the museum is very nice). Now, if only they had used metric…
posted by bouvin at 1:22 PM on February 19
posted by bouvin at 1:22 PM on February 19
I just watched a murder mystery on television where the way the murder was committed was by substituting a different measuring stick so the person bungie jumping measured out too much bungie and died.
It's interesting how much trust we place in those things that have lines on them. And this is different from doing an imperial/metric confusion.
posted by hippybear at 1:38 PM on February 19 [2 favorites]
It's interesting how much trust we place in those things that have lines on them. And this is different from doing an imperial/metric confusion.
posted by hippybear at 1:38 PM on February 19 [2 favorites]
Re: the Gimli Glider: How did a fight from Montreal to Edmonton end up over the Atlantic ocean?
posted by sudasana at 1:39 PM on February 19 [1 favorite]
posted by sudasana at 1:39 PM on February 19 [1 favorite]
The mass of the International Prototype Kilogram is, by definition 1 kg, but appears to be losing mass for unknown reasons. In 2019 it was redefined in terms of more replicable standards. Not sure if any hijinks occurred due to the discrepancy.
posted by autopilot at 1:44 PM on February 19 [3 favorites]
posted by autopilot at 1:44 PM on February 19 [3 favorites]
Weirdly all the international prototypes have been losing mass. I seem to remember the official meter was deprecated because it was getting shorter and is now defined by some kind of light wavelength or something. Which honestly seems to me, as a normal person, to be more difficult to use as a standard than a bit of metal.
posted by hippybear at 1:48 PM on February 19
posted by hippybear at 1:48 PM on February 19
Oops. I mixed up aircraft incidents — the Gimli Glider flew 70 km over Canada, while the Azores Glider is the longest passenger aircraft glide at 121 km while enroute from Toronto to Portugal (which goes over the Atlantic).
posted by autopilot at 1:57 PM on February 19 [9 favorites]
posted by autopilot at 1:57 PM on February 19 [9 favorites]
I have a scale ruler (they're generally oriented with three spines, so 6 different measurement scales) , where one side of it is marked off on the major scale as inches, but within that inch it's marked off in 10ths. That was a doozy to figure out a little too late.
If you hang around carpentry groups, you'll find posts showing poorly made tape measures, not just where they don't start at zero but they'll hold two tapes next to each other and one will be every so slightly smaller than the other. There's a tradition that when working on a project you always use the same tape measure, don't switch or you could be slightly off.
As far as types of measurement: I like watching British carpentry and furniture restoration shows, and I am amused that they do a lot still in imperial units -- but then flip back to metric without a thought. If you do it all the time you must be able to calculate in your head but I'd be constantly on my calculator.
posted by AzraelBrown at 2:27 PM on February 19 [6 favorites]
If you hang around carpentry groups, you'll find posts showing poorly made tape measures, not just where they don't start at zero but they'll hold two tapes next to each other and one will be every so slightly smaller than the other. There's a tradition that when working on a project you always use the same tape measure, don't switch or you could be slightly off.
As far as types of measurement: I like watching British carpentry and furniture restoration shows, and I am amused that they do a lot still in imperial units -- but then flip back to metric without a thought. If you do it all the time you must be able to calculate in your head but I'd be constantly on my calculator.
posted by AzraelBrown at 2:27 PM on February 19 [6 favorites]
There's obviously going to be a lot of smug Europeans and self-flagellating Americans in this thread, but part of the reason why English units still exist is because they were so much more effectively centralized and standardized at a much early point in time than their competitors.
Heck, even Sweden embarrasses itself constantly (without having moral compass to acknowledge it), by using the pre-metric unit mil i automobile-scale distances and fuel economy.
posted by groda at 2:28 PM on February 19 [2 favorites]
Heck, even Sweden embarrasses itself constantly (without having moral compass to acknowledge it), by using the pre-metric unit mil i automobile-scale distances and fuel economy.
posted by groda at 2:28 PM on February 19 [2 favorites]
part of the reason why English units still exist is because they were so much more effectively centralized and standardized at a much early point in time
Unfortunately, not quite early enough to get in before the American revolution, so they're on Queen Anne units here rather than Imperial. Smaller pints and gallons is the most obvious impact.
posted by rhamphorhynchus at 2:39 PM on February 19 [3 favorites]
Unfortunately, not quite early enough to get in before the American revolution, so they're on Queen Anne units here rather than Imperial. Smaller pints and gallons is the most obvious impact.
posted by rhamphorhynchus at 2:39 PM on February 19 [3 favorites]
Weirdly all the international prototypes have been losing mass.
Interesting; I would think they would gain mass due to oxidation.
posted by TedW at 2:40 PM on February 19
Interesting; I would think they would gain mass due to oxidation.
posted by TedW at 2:40 PM on February 19
I have a scale ruler (they're generally oriented with three spines, so 6 different measurement scales) , where one side of it is marked off on the major scale as inches, but within that inch it's marked off in 10ths.
So an engineer’s scale as opposed to an architect’s scale? (Those drafting classes in high school really stuck with me!)
posted by TedW at 2:47 PM on February 19 [2 favorites]
So an engineer’s scale as opposed to an architect’s scale? (Those drafting classes in high school really stuck with me!)
posted by TedW at 2:47 PM on February 19 [2 favorites]
Unfortunately, not quite early enough to get in before the American revolution, so they're on Queen Anne units here rather than Imperial. Smaller pints and gallons is the most obvious impact.
I get that if you're from one of the countries that don't speak Foreign, that this might seem like a big deal, but most of Europe prior to Europe losing to Napoleon had this level of unit diversity on a province to province level.
posted by groda at 2:50 PM on February 19 [3 favorites]
I get that if you're from one of the countries that don't speak Foreign, that this might seem like a big deal, but most of Europe prior to Europe losing to Napoleon had this level of unit diversity on a province to province level.
posted by groda at 2:50 PM on February 19 [3 favorites]
So an engineer’s scale as opposed to an architect’s scale?
Yeah, but it had architect scales (fractions of inches) on the rest of the sides. It was weird. I think I may still have it in a box somewhere, I should check.
posted by AzraelBrown at 3:13 PM on February 19
Yeah, but it had architect scales (fractions of inches) on the rest of the sides. It was weird. I think I may still have it in a box somewhere, I should check.
posted by AzraelBrown at 3:13 PM on February 19
In a more modern example I noticed that my Garmin watch offers a badge for hitting hydration goals every day for 30 days. The goal is supposed to represent 64 fl ozs per day of fluid intake (ie 4 US pints), meaning this is just under 1900ml per day. However, when converted to England they have translated this to 4 English pints (80 fl ozs in imperial) which is 2273ml, which effectively means drinking about 2500ml to hit the goal.
posted by biffa at 3:20 PM on February 19 [3 favorites]
posted by biffa at 3:20 PM on February 19 [3 favorites]
Take heart. The US has both the "international foot" and the "survey foot"; the two differ by 2 parts per million.
retired in 2023 -> https://www.nist.gov/pml/us-surveyfoot
posted by 922257033c4a0f3cecdbd819a46d626999d1af4a at 3:29 PM on February 19 [2 favorites]
retired in 2023 -> https://www.nist.gov/pml/us-surveyfoot
posted by 922257033c4a0f3cecdbd819a46d626999d1af4a at 3:29 PM on February 19 [2 favorites]
There are other confusing (to the unwary) rules, for example the shrink rule used in pattern making for metal casting.
The original drawing is made actual size using a standard rule (assuming you’re drafting it by hand) and then, to account for the shrinkage that occurs during casting, the pattern maker lays out his pattern using a slightly oversize ruler — somewhere between 1/12” and 5/16” per foot, depending on the metal being used. Every division is scaled appropriately, so apart from any labeling telling you what it is, it isn’t easy to see that it’s not a standard ruler just from the scale itself.
Potters have similar rules with different shrink ratios.
Using one for the wrong thing would be very confusing.
posted by Quinbus Flestrin at 4:10 PM on February 19 [6 favorites]
The original drawing is made actual size using a standard rule (assuming you’re drafting it by hand) and then, to account for the shrinkage that occurs during casting, the pattern maker lays out his pattern using a slightly oversize ruler — somewhere between 1/12” and 5/16” per foot, depending on the metal being used. Every division is scaled appropriately, so apart from any labeling telling you what it is, it isn’t easy to see that it’s not a standard ruler just from the scale itself.
Potters have similar rules with different shrink ratios.
Using one for the wrong thing would be very confusing.
posted by Quinbus Flestrin at 4:10 PM on February 19 [6 favorites]
> defined by some kind of light wavelength ... more difficult to use as a standard than a bit of metal
The thing to keep in mind is that this is the definition of the unit -- it's not meant for normal people to use, it's meant for the scientists at the standards bodies (in the US that's NIST) to define the unit. Regular people will use samples/copies that are traceable to these bodies.
(Pedantic note: it's the second that's defined by the frequency of a certain cesium atom; the meter is defined by setting the speed of light in vacuum to be 299 792 458 meters/second exactly. I find this strangely pleasing!)
posted by phliar at 4:25 PM on February 19 [4 favorites]
The thing to keep in mind is that this is the definition of the unit -- it's not meant for normal people to use, it's meant for the scientists at the standards bodies (in the US that's NIST) to define the unit. Regular people will use samples/copies that are traceable to these bodies.
(Pedantic note: it's the second that's defined by the frequency of a certain cesium atom; the meter is defined by setting the speed of light in vacuum to be 299 792 458 meters/second exactly. I find this strangely pleasing!)
posted by phliar at 4:25 PM on February 19 [4 favorites]
for example the shrink rule used in pattern making for metal casting
Oh wow, I'd completely forgotten about this but yes, when I was working making jewelry, you'd totally have to calculate for how much smaller the metal would be after casting. And this is a weird thing because you'd create a wax figure and then would surround that with plaster and melt the wax out and fill the void with metal.. and you'd think that the end result would be the size of the void left by the wax after you'd melted it out BUT IT WAS NOT THE SAME.
It's one of the more peculiar things I've encountered in my life -- that you can pour molten metal into a void to cast it into a specific shape but it will not necessarily be the size you expected it to be.
posted by hippybear at 4:31 PM on February 19 [3 favorites]
Oh wow, I'd completely forgotten about this but yes, when I was working making jewelry, you'd totally have to calculate for how much smaller the metal would be after casting. And this is a weird thing because you'd create a wax figure and then would surround that with plaster and melt the wax out and fill the void with metal.. and you'd think that the end result would be the size of the void left by the wax after you'd melted it out BUT IT WAS NOT THE SAME.
It's one of the more peculiar things I've encountered in my life -- that you can pour molten metal into a void to cast it into a specific shape but it will not necessarily be the size you expected it to be.
posted by hippybear at 4:31 PM on February 19 [3 favorites]
→
A mil is 10 km, though; no?
Whatever happened to Vasa, Sweden forever redeemed itself in the world of metrology by bringing us Carl Edvard Johansson. Not merely did he invent gauge blocks, but he unified the inch to 25.4 mm because his blocks were that length at 20 °C. The American and UK standards were so close and also measured at different temperatures, so everyone caved and used Johanssen's number.
posted by scruss at 4:34 PM on February 19 [10 favorites]
Heck, even Sweden embarrasses itself constantly (without having moral compass to acknowledge it), by using the pre-metric unit mil i automobile-scale distances and fuel economy.
A mil is 10 km, though; no?
Whatever happened to Vasa, Sweden forever redeemed itself in the world of metrology by bringing us Carl Edvard Johansson. Not merely did he invent gauge blocks, but he unified the inch to 25.4 mm because his blocks were that length at 20 °C. The American and UK standards were so close and also measured at different temperatures, so everyone caved and used Johanssen's number.
posted by scruss at 4:34 PM on February 19 [10 favorites]
I’m terrible at measuring things. I take some solace from all this ruler agony.
Weirdly, all the international prototypes have been losing mass . . . sounds to me like the set-up for a dynamite (and terrible) Christopher Nolan / Nic Cage film.
posted by Don.Kinsayder at 5:48 PM on February 19 [5 favorites]
Weirdly, all the international prototypes have been losing mass . . . sounds to me like the set-up for a dynamite (and terrible) Christopher Nolan / Nic Cage film.
posted by Don.Kinsayder at 5:48 PM on February 19 [5 favorites]
I deal with some stuff at work that mixes and matches all three units...
A long ton (aka imperial ton or gross ton) is 2,240 pounds
A short ton (aka ton) is 2,000 pounds
A metric ton (aka tonne) is 2,204 pounds, or 1,000 kg
Then in some casual communications they just say "ton" and worse... they're translated documents because we deal with hundreds of suppliers all over the world, many contracts aren't in English to begin with.
It's enough to make one despair but on the other hand if this work was easy we wouldn't have a job, so...
posted by xdvesper at 6:24 PM on February 19 [3 favorites]
A long ton (aka imperial ton or gross ton) is 2,240 pounds
A short ton (aka ton) is 2,000 pounds
A metric ton (aka tonne) is 2,204 pounds, or 1,000 kg
Then in some casual communications they just say "ton" and worse... they're translated documents because we deal with hundreds of suppliers all over the world, many contracts aren't in English to begin with.
It's enough to make one despair but on the other hand if this work was easy we wouldn't have a job, so...
posted by xdvesper at 6:24 PM on February 19 [3 favorites]
that you can pour molten metal into a void to cast it into a specific shape but it will not necessarily be the size you expected it to be.
IIRC this was a big sticking point for Adam Savage when he was trying desperately to recreate the Maltese falcon. I believe he goes into detail in an old TED talk about it.
posted by potent_cyprus at 6:40 PM on February 19 [2 favorites]
IIRC this was a big sticking point for Adam Savage when he was trying desperately to recreate the Maltese falcon. I believe he goes into detail in an old TED talk about it.
posted by potent_cyprus at 6:40 PM on February 19 [2 favorites]
There's obviously going to be a lot of smug Europeans and self-flagellating Americans in this thread
also the pragmatically-resigned Canadians
posted by ZaphodB at 7:55 PM on February 19 [5 favorites]
also the pragmatically-resigned Canadians
posted by ZaphodB at 7:55 PM on February 19 [5 favorites]
confusion of Swedish and Imperial inch and foot units.
It’s been known to happen since then.
posted by Naberius at 8:04 PM on February 19
It’s been known to happen since then.
posted by Naberius at 8:04 PM on February 19
The Patriot Missile used a floating point time counter which meant that after 100 hours of operation the integer part no longer fit into a 24-bit register
Patriot missile control system. If your Patriot Missile has been in flight for 100 hours, you have different problems.
posted by zamboni at 9:15 PM on February 19 [3 favorites]
Patriot missile control system. If your Patriot Missile has been in flight for 100 hours, you have different problems.
posted by zamboni at 9:15 PM on February 19 [3 favorites]
Oh, I had meant to include something about short/long/metric tons! Those last two are *so close*.
Which reminds me that during the Manhattan Project when Oakridge needed to copper to build the magnets for their uranium refinement, they couldn't get it due to rationing. Instead they asked the US Treasury for six thousand tons (not sure which sort!) of silver to make the wires, "Treasury Secretary Bell indignantly informed Colonel Nichols that the Treasury’s unit of measure was the troy ounce".
That is also part of a riddle: which weighs more, a pound of feathers or a pound of gold? The feathers, since gold is measured in Troy weights. A Troy Ounce of gold weighs about 10% more than an avoirdupois ounce of feathers (31.1 vs 28.3 grams), except that there are only 12 Troy ounces in a Troy pound compared to the normal 16, so the pound of feathers is overall heavier than the gold (453 vs 373 grams).
posted by autopilot at 12:14 AM on February 20 [3 favorites]
Which reminds me that during the Manhattan Project when Oakridge needed to copper to build the magnets for their uranium refinement, they couldn't get it due to rationing. Instead they asked the US Treasury for six thousand tons (not sure which sort!) of silver to make the wires, "Treasury Secretary Bell indignantly informed Colonel Nichols that the Treasury’s unit of measure was the troy ounce".
That is also part of a riddle: which weighs more, a pound of feathers or a pound of gold? The feathers, since gold is measured in Troy weights. A Troy Ounce of gold weighs about 10% more than an avoirdupois ounce of feathers (31.1 vs 28.3 grams), except that there are only 12 Troy ounces in a Troy pound compared to the normal 16, so the pound of feathers is overall heavier than the gold (453 vs 373 grams).
posted by autopilot at 12:14 AM on February 20 [3 favorites]
Oh, I had meant to include something about short/long/metric tons! Those last two are *so close*.
The difference between the three actually came up on Metafilter in a thread about a three tonne wombat.
posted by zamboni at 4:26 AM on February 20
The difference between the three actually came up on Metafilter in a thread about a three tonne wombat.
posted by zamboni at 4:26 AM on February 20
_How Not to Make a Prize-Winning Quilt_ (a comic classic) includes finding out that the hem gauge on the sewing machine wasn't accurate.
posted by Nancy Lebovitz at 4:46 AM on February 20
posted by Nancy Lebovitz at 4:46 AM on February 20
A simple wondering: Could the switch to metric have been encouraged by simply choosing shorter names?
Brought to you by the tendency to mentally abbreviate "miles per hour" as the phonetic mff. (And maybe a few years of science and UX practice, but still.)
posted by SunSnork at 6:08 AM on February 20
Brought to you by the tendency to mentally abbreviate "miles per hour" as the phonetic mff. (And maybe a few years of science and UX practice, but still.)
posted by SunSnork at 6:08 AM on February 20
"You know what? 'Kilowatt-hour per sol' is a pain in the ass to say. I'm gonna invent a new scientific unit name. One kilowatt-hour per sol is... it can be anything... um... I suck at this... I'll call it a 'pirate-ninja'."
--Andy Weir, The Martian
posted by hovey at 6:18 AM on February 20 [3 favorites]
--Andy Weir, The Martian
posted by hovey at 6:18 AM on February 20 [3 favorites]
We've taken numerous measurements to ensure this post will fit into the Sidebar and Best Of blog!
posted by Brandon Blatcher at 6:58 AM on February 20 [1 favorite]
posted by Brandon Blatcher at 6:58 AM on February 20 [1 favorite]
Brought to you by the tendency to mentally abbreviate "miles per hour" as the phonetic mff
Great idea, that could be extended to work with the centimetre, the kilonewton-per-tesla, the ampere-second, the farad-per-kilogram, the deciampere-per metre, and the watt-per-ampere-per-nanokelvin-per-angstrom!
posted by polytope subirb enby-of-piano-dice at 7:46 AM on February 20 [1 favorite]
Great idea, that could be extended to work with the centimetre, the kilonewton-per-tesla, the ampere-second, the farad-per-kilogram, the deciampere-per metre, and the watt-per-ampere-per-nanokelvin-per-angstrom!
posted by polytope subirb enby-of-piano-dice at 7:46 AM on February 20 [1 favorite]
(I am very knowledgable about industrial-scale magnets and capacitors and I spend a lot of time thinking deeply about superconductivity)
posted by polytope subirb enby-of-piano-dice at 7:52 AM on February 20
posted by polytope subirb enby-of-piano-dice at 7:52 AM on February 20
Could the switch to metric have been encouraged by simply choosing shorter names?
It might have helped, but what really would have made it easier was waiting just a bit longer for widespread computerization, until people weren't doing quite so many unit conversions in their heads anymore. There are some real advantages to doing fractional math in larger bases, and the US/English measurement system uses a lot of 12ths, 16ths, etc.
posted by Kadin2048 at 7:52 AM on February 20
It might have helped, but what really would have made it easier was waiting just a bit longer for widespread computerization, until people weren't doing quite so many unit conversions in their heads anymore. There are some real advantages to doing fractional math in larger bases, and the US/English measurement system uses a lot of 12ths, 16ths, etc.
posted by Kadin2048 at 7:52 AM on February 20
Wasn’t it a metric/imperial snafu that caused Hubble to launch with nearsighted optics?
posted by Thorzdad at 8:04 AM on February 20
posted by Thorzdad at 8:04 AM on February 20
No.
The spacing of the field lens in the corrector was to have been done by laser measurements off the end of an invar bar. Instead of illuminating the end of the bar, however, the laser in fact was reflected from a worn spot on a black-anodized metal cap placed over the end of the bar to isolate its center (visible through a hole in the cap). The technician who performed the test noted an unexpected gap between the field lens and its supporting structure in the corrector and filled it in with an ordinary metal washer.posted by zamboni at 8:07 AM on February 20 [1 favorite]
That's just the first why. Ultimately,
The commission blamed the failings primarily on Perkin-Elmer. Relations between NASA and the optics company had been severely strained during the telescope construction, due to frequent schedule slippage and cost overruns. NASA found that Perkin-Elmer did not review or supervise the mirror construction adequately, did not assign its best optical scientists to the project (as it had for the prototype), and in particular did not involve the optical designers in the construction and verification of the mirror. While the commission heavily criticized Perkin-Elmer for these managerial failings, NASA was also criticized for not picking up on the quality control shortcomings, such as relying totally on test results from a single instrument.posted by zamboni at 8:13 AM on February 20
Heh.
But, today some of our engineers can CAD a 5 meter fusion machine "Wendelstein 7-X" with a magnetic field precision of some 100 microns under superconductive magnetic load.
Then they CAD the entire thing again, with up to 5cm unwarping without the magnetic forces.
Then they CAD it a third time, this time to allow for thermal compression before supercooling from room temperature to very close to absolute zero.
Then they build it, fire it up and hope none of the manual welding gives. Sometimes it still does and then the magnetic field can collapse instantly in what they call a quench. The whole thing returns from the first state to the last, which is something high-temperature ceramic superconductors currently don't survive.
And all without firing cannons or other belligerent intent!
posted by flamewise at 8:25 AM on February 20 [2 favorites]
But, today some of our engineers can CAD a 5 meter fusion machine "Wendelstein 7-X" with a magnetic field precision of some 100 microns under superconductive magnetic load.
Then they CAD the entire thing again, with up to 5cm unwarping without the magnetic forces.
Then they CAD it a third time, this time to allow for thermal compression before supercooling from room temperature to very close to absolute zero.
Then they build it, fire it up and hope none of the manual welding gives. Sometimes it still does and then the magnetic field can collapse instantly in what they call a quench. The whole thing returns from the first state to the last, which is something high-temperature ceramic superconductors currently don't survive.
And all without firing cannons or other belligerent intent!
posted by flamewise at 8:25 AM on February 20 [2 favorites]
Basically every computer-thingy that has some kind of size-measuring-thingy on it has to decide whether it's going to measure and report in powers of ten (kilobytes, megabytes, gigabytes) or nearby powers of two (kibibytes, mebibytes, gibibytes). The powers of two are what are _usually_ meant, but not always, and sometimes it's a mix (eg. reporting a megabyte as 1000 kilobytes where you define a kilobyte as 1024 bytes).
For a long time people were imprecise about this with all the consequences you would expect. It is gradually getting worked out, but a lot of people just can't bring themselves to use the kibi and mebi prefixes because they sound so cutesy.
posted by ead at 10:21 AM on February 20
For a long time people were imprecise about this with all the consequences you would expect. It is gradually getting worked out, but a lot of people just can't bring themselves to use the kibi and mebi prefixes because they sound so cutesy.
posted by ead at 10:21 AM on February 20
Ok here is something more amusing: yes Canada didn't manage to fully metricate and yes it was a stupid bloody political thing (in case you thought turning random subjects into culture war themes was new) BUT did you also know that Steward Brand of the Whole Earth Review was an ardent anti-metric advocate who constantly published articles about resisting metrication as some kind of military-industrial conspiracy? TRUE FACTS.
posted by ead at 11:03 AM on February 20 [1 favorite]
posted by ead at 11:03 AM on February 20 [1 favorite]
Wait, is that an African or a European swallow?
posted by spitbull at 11:09 AM on February 20 [2 favorites]
posted by spitbull at 11:09 AM on February 20 [2 favorites]
Basically every computer-thingy that has some kind of size-measuring-thingy on it has to decide whether it's going to measure and report in powers of ten (kilobytes, megabytes, gigabytes) or nearby powers of two (kibibytes, mebibytes, gibibytes).
I've sometimes thought that the real measurement One Ring is to abandon SI in favor of, well, SI but binary so computers can chomp it up more easily.
The basilisk will remember such attempts with favor.
posted by GCU Sweet and Full of Grace at 12:11 PM on February 20 [1 favorite]
I've sometimes thought that the real measurement One Ring is to abandon SI in favor of, well, SI but binary so computers can chomp it up more easily.
The basilisk will remember such attempts with favor.
posted by GCU Sweet and Full of Grace at 12:11 PM on February 20 [1 favorite]
Every once in a while, I'll read about someone's sewing project going awry, and it will turn out to be because they were using (unbeknownst to them) a measuring tape graduated in cun/Chinese inches rather than Imperial/customary inches, making everything off by about 30%.
posted by JiBB at 9:47 PM on February 20
posted by JiBB at 9:47 PM on February 20
At my old hackerspace there was one of those triple-ruler things where all six of the scales were subtly wrong. One was decimal inches (so 10 divisions per inch instead of the usual 16), one was pica (*almost* 1/6 of an inch), and I think the others were leading guage (that get bigger each step) and maybe some sort of scaled values. Basically not a single edge was useful and some were just close enough that you might be fooled in using it. After several years of picking it up, noticing that it wasn't right, and putting it back into the toolbox, I finally doomed it.
posted by autopilot at 9:15 AM on February 21
posted by autopilot at 9:15 AM on February 21
While usually I'm a fan of metric (despite my complaints about decimal inches above), there is a special place in my brain for Natural Units. For most of them the length and time values are selected so that the speed of light c is equal to 1. This in turn makes the mass-energy equivalence even more equivalent: e=mc2 simplifies to just e=m because 1 squared is still 1.
(I also adore the Barn/Outhouse/Shed as units of area and the derived unit of Inverse Femtobarns per year to measure particle collider productivity)
posted by autopilot at 9:23 AM on February 21
(I also adore the Barn/Outhouse/Shed as units of area and the derived unit of Inverse Femtobarns per year to measure particle collider productivity)
posted by autopilot at 9:23 AM on February 21
Agreed that we Canadians definitely have an odd relationship with metric measurements... I know how tall I am in both but I don't think I've ever actually answered the question with 185cm. I'm sure some of the blame is proximity to the states, but some of it has got to be Canadians ourselves.
One thing that some friends visiting have called out as odd is that if you ask many Canadians how far something is we'll almost always give it to you as a time. Oh Montreal is 5 hours away... or oh that park is 10 minutes away. I don't know anyone that would first give you an actual distance.
I'm curious if we're really wierd in this or just a little bit more prone to it than the "normal"
posted by cirhosis at 12:38 PM on February 21
One thing that some friends visiting have called out as odd is that if you ask many Canadians how far something is we'll almost always give it to you as a time. Oh Montreal is 5 hours away... or oh that park is 10 minutes away. I don't know anyone that would first give you an actual distance.
I'm curious if we're really wierd in this or just a little bit more prone to it than the "normal"
posted by cirhosis at 12:38 PM on February 21
if you ask many Canadians how far something is we'll almost always give it to you as a timeAlso commonplace in the US, for anything you have to drive to.
Almost every time I hear someone bring this behavior up, they think it's a regionalism of theirs, but the region in question has been Southern California, the Upper Midwest, Utah, and now Canada. And I think I've heard it done unselfconsciously by people from all over. I'd bet it's everywhere our car culture is.
On the subject of regional self-image: I grew up in the Pacific Northwest and sojourned elsewhere. In 2020 I moved back to the Northwest from Ohio, and I got to hear a couple of "well, I don't know what people are like in Ohio, but here's what we're like in the Northwest" spiels from people who only had my backstory as far as my last residence. But in all honesty, the main differences are that Central Ohio has more politeness in traffic, more profanity in person, tornado preparedness instead of earthquake preparedness, and a slight preponderance of Methodists instead of a slight preponderance of Lutherans.
posted by eritain at 2:43 PM on February 21 [1 favorite]
eritain, I find that super interesting. But I don't think it's quite as everywhere as you think it is as these visiting friends were in fact from the US... But glad to hear it's not just Canadians :)
posted by cirhosis at 6:41 PM on February 21
posted by cirhosis at 6:41 PM on February 21
I seem to notice that the time-as-distance measurement tends to come from places that have alot of long-distance travel. So maybe not New York, but definitely Texas.
posted by LizBoBiz at 7:07 PM on February 21
posted by LizBoBiz at 7:07 PM on February 21
In places with more density/congestion and/or multiple modes of transport, travel time frequently does not directly correlate to distance.
posted by zamboni at 9:27 AM on February 22
posted by zamboni at 9:27 AM on February 22
I read the Mountain Project forum ‘injuries and accidents’ semi-occasionally to keep my problem-solving mind sharp when it comes to thinking about accident avoidance in climbing. It’s really noticeable that a preponderance of the accidents that happen in the US involve someone lowering themselves (or being lowered) down a route on a rope that’s not long enough, resulting in a fall. It’s also noticeable that climbing routes in the US are measured (and discussed) in feet, while ropes are measured (and sold) in metres. I can’t help but think that the two things are related.
(The lesson most people on the forum take away is just that climbers should always ‘close the system’ I.e. put a knot in the end of the rope so they don’t end up dropping off the end of it. That’ll work, and it’s the right practice to adopt, but the more general problem about the mismatched units is still something to properly recognise).
posted by Joeruckus at 1:10 AM on February 23 [2 favorites]
(The lesson most people on the forum take away is just that climbers should always ‘close the system’ I.e. put a knot in the end of the rope so they don’t end up dropping off the end of it. That’ll work, and it’s the right practice to adopt, but the more general problem about the mismatched units is still something to properly recognise).
posted by Joeruckus at 1:10 AM on February 23 [2 favorites]
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Timer overflows aren't exactly unit mistakes, although they are sort of related. Y2K is the most famous, of course. The Patriot Missile used a floating point time counter, which meant that after 100 hours of operation the integer part no longer fit into a 24-bit register and lead to a tragedy in Iraq. More humorously, Windows 95 has a timer that overflows at 49.7 days of uptime, although it took years before the bug was detected (and decades before it was demoed). Finally, we're now only 14 years away from the end of time, which is a key part of my retirement plan since I'm certain there will still be 32-bit systems out there.
posted by autopilot at 12:33 PM on February 19 [12 favorites]