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2153: "Effects of High Altitude"

Posted: Wed May 22, 2019 6:10 pm UTC
by jozwa
Image
Title text: "If she'd lived in Flagstaff (elevation 6,903 feet), Cruella de Vil would only have needed 89 dalmatians for her coat."

Had to google what the regular boiling temp for water is in Fahrenheit

Re: 2153: "Effects of High Altitude"

Posted: Wed May 22, 2019 6:14 pm UTC
by foerno
no metric? seriously? :?

Re: 2153: "Effects of High Altitude"

Posted: Wed May 22, 2019 6:22 pm UTC
by freezeblade
jozwa wrote:Had to google what the regular boiling temp for water is in Fahrenheit


Madness, 212 degrees at sea level makes perfect sense...right?

Re: 2153: "Effects of High Altitude"

Posted: Wed May 22, 2019 7:07 pm UTC
by yakkoTDI
jozwa wrote:Had to google what the regular boiling temp for water is in Fahrenheit


Metric would be so much better.

Temperature is just as dumb as distance.

"To remember how many feet there are in a mile, you just need use 5 tomatoes; five to-mate-oes sounds like five, two, eight, 0 and there’s 5280 feet in a mile.
To remember how many meters there are in a kilometre you just remember “1000” because the system of measurement in the rest of the world wasn’t invented by a drunk mathematician rolling dice."

Re: 2153: "Effects of High Altitude"

Posted: Wed May 22, 2019 7:39 pm UTC
by sotanaht
yakkoTDI wrote:
jozwa wrote:Had to google what the regular boiling temp for water is in Fahrenheit


Metric would be so much better.

Temperature is just as dumb as distance.

"To remember how many feet there are in a mile, you just need use 5 tomatoes; five to-mate-oes sounds like five, two, eight, 0 and there’s 5280 feet in a mile.
To remember how many meters there are in a kilometre you just remember “1000” because the system of measurement in the rest of the world wasn’t invented by a drunk mathematician rolling dice."

Interesting mnemonic. I've never bothered remembering how many feet are in a mile because it is in no way important to the way I use feet or miles. I never need to use miles with that much precision or feet at that large a distance.

I like Fahrenheit because the 0-100 perfectly measures the range of reasonably livable temperatures. 0 is very cold and 100 is very hot, and anything outside of that range is extremely notable. In Celsius, 0 is kind of cold and 100 is very lethal. That 0 and 100 are both arbitrary relative to water isn't really that different than how metric works in general, with such measures as the kilogram being completely arbitrary unto themselves.

Re: 2153: "Effects of High Altitude"

Posted: Wed May 22, 2019 7:44 pm UTC
by cryptoengineer
Fun fact:

Computer hard drives (the spinny kind, not solid state), rely on microscopic cushion of air between the head and the media. Most are unsealed, with a filter between the interior and the outside world. They thus have an altitude limit, beyond which headc crashes become common. Few drives are rated for above 10,000 feet (~3000 meters).

Above that, you need to use expensive, hermetically sealed drives, or nowadays, SSDs. This is a real issue for people working in mountain top observatories and flying labs.

Re: 2153: "Effects of High Altitude"

Posted: Wed May 22, 2019 7:52 pm UTC
by cryptoengineer
sotanaht wrote:>the kilogram being completely arbitrary unto themselves.


As of a couple days ago, the kilogram has been redefined in terms of physical constants: the Planck constant, the speed of light and the resonant frequency of the caesium atom: https://www.sciencealert.com/tomorrow-the-definition-of-the-kilogram-will-change-forever-here-s-what-that-really-means

Re: 2153: "Effects of High Altitude"

Posted: Wed May 22, 2019 8:09 pm UTC
by Pfhorrest
cryptoengineer wrote:
sotanaht wrote:>the kilogram being completely arbitrary unto themselves.


As of a couple days ago, the kilogram has been redefined in terms of physical constants: the Planck constant, the speed of light and the resonant frequency of the caesium atom: https://www.sciencealert.com/tomorrow-the-definition-of-the-kilogram-will-change-forever-here-s-what-that-really-means


And it was originally defined in reference to water as well, just like Celsius: 1g was the weight of 1mL of water, 1mL being 1cm cubed, 1cm being 1/100 of a meter, a meter being something like 1/10,000th the distance between the north pole and the equator (I forget if that last part is quite accurate).

Also, a mile used to make more sense, in its original definition: it was a mille-yard, one thousand yards, a yard there being the Roman yard equal to five Roman feet. You'd think the English mile would thus be one thousand English yards, those being three English feet -- which would make it very close to a kilometer, as an English yard is very close to a meter -- but no, history had to go and make things weird.

(There's an Italian road rally called the Mille Miglia, "thousand miles", and it would be really nice if that was just one million yards, but alas it's not because history is weird).

Re: 2153: "Effects of High Altitude"

Posted: Wed May 22, 2019 8:19 pm UTC
by sotanaht
cryptoengineer wrote:
sotanaht wrote:>the kilogram being completely arbitrary unto themselves.


As of a couple days ago, the kilogram has been redefined in terms of physical constants: the Planck constant, the speed of light and the resonant frequency of the caesium atom: https://www.sciencealert.com/tomorrow-the-definition-of-the-kilogram-will-change-forever-here-s-what-that-really-means

That doesn't make it any less arbitrary. The Kilogram is now defined as some bullshit multiple of something that's a thousand times harder to remember than 5280, and every other metric measurement is defined as something relative to the kilogram (and also some other constant, but the measures are all meant to be based on each other). Except for Celsius, which has nothing to do with the kilogram and the only scientific merit that it has is that it's fixed points are based on water in some slightly useful way. There are no funky unit conversions to mess up the system regardless of whether you use F or C and even converting to K is pretty straightforward. You can make an argument for the practicality of metric in other weights and measures, but purely for the purpose of temperature, the two systems are equivalent.

Re: 2153: "Effects of High Altitude"

Posted: Wed May 22, 2019 9:47 pm UTC
by GlassHouses
Pfhorrest wrote:Also, a mile used to make more sense, in its original definition: it was a mille-yard, one thousand yards, a yard there being the Roman yard equal to five Roman feet.

The word mile, and other European names for units of length like mijl or Meile, come from the Latin Mille Passuum, meaning one thousand paces, and sometimes abbreviated to simply Mille.

Re: 2153: "Effects of High Altitude"

Posted: Wed May 22, 2019 10:00 pm UTC
by da Doctah
Water freezes at 32 degrees Fahrenheit and boils at 212 degrees Fahrenheit.

Thus, there are 180 degrees between freezing and boiling.

Just as there are 180 degrees between north and south.

What could be simpler?

(Also, the diameter of the sun in miles is 10 times the number of seconds in a day, proving that miles are a more natural unit of distance than any of those meat things.)

Re: 2153: "Effects of High Altitude"

Posted: Wed May 22, 2019 10:02 pm UTC
by cryptoengineer
sotanaht wrote:
cryptoengineer wrote:
sotanaht wrote:>the kilogram being completely arbitrary unto themselves.


As of a couple days ago, the kilogram has been redefined in terms of physical constants: the Planck constant, the speed of light and the resonant frequency of the caesium atom: https://www.sciencealert.com/tomorrow-the-definition-of-the-kilogram-will-change-forever-here-s-what-that-really-means

That doesn't make it any less arbitrary. The Kilogram is now defined as some bullshit multiple of something that's a thousand times harder to remember than 5280, and every other metric measurement is defined as something relative to the kilogram (and also some other constant, but the measures are all meant to be based on each other). Except for Celsius, which has nothing to do with the kilogram and the only scientific merit that it has is that it's fixed points are based on water in some slightly useful way. There are no funky unit conversions to mess up the system regardless of whether you use F or C and even converting to K is pretty straightforward. You can make an argument for the practicality of metric in other weights and measures, but purely for the purpose of temperature, the two systems are equivalent.


I think we're dealing with different definitions of 'arbitrary'. The old standard for kilogram was ' the mass of a certain chunk of metal under a bell jar in Paris'. Problem was, there was only one of it; if we lost it, or it got damaged, we were SOL. In fact, its weight *did* vary against other chunks of metal which were supposed to be correct copies, and there was no way of knowing which was more correct.

The new definition eliminates reliance on a particular, arbitrary artifact. Even if every weight, scale, and other measuring device in existence was destroyed, the SI system is now defined in ways which could be exactly reproduced from written records.

The meter, btw, started out as 'One 10 millionth of the distance from the equator to the North Pole, at the longitude of Paris'. However, the Earth is more lumpy and irregular than a caesium atom. The Kilo started out as the mass of 1000 cm^3 of water at 4C.

Re: 2153: "Effects of High Altitude"

Posted: Wed May 22, 2019 10:09 pm UTC
by MarkGyver
da Doctah wrote:Thus, there are 180 degrees between freezing and boiling.

Just as there are 180 degrees between north and south.


I've spent the overwhelming majority of my decades-long life in Fahrenheit Land, and I think this is the first time I have a chance to remember the boiling point of water in that system. I think I remember the freezing point because it's a power of 2.

Re: 2153: "Effects of High Altitude"

Posted: Wed May 22, 2019 11:32 pm UTC
by gmalivuk
foerno wrote:
no metric? seriously? :?

Welcome to this comic by an American about being a mile from somewhere.

Re: 2153: "Effects of High Altitude"

Posted: Thu May 23, 2019 1:03 am UTC
by wgrandbois
I always find it funny how many "high altitude" baking instructions list 3500-7000 feet, like after that you're just SOL. Didn't know about the hard disks over 10,000 feet thing. I haven't had an issue yet, but it might make me think twice before getting my laptop out at the top of a pass.

Re: 2153: "Effects of High Altitude"

Posted: Thu May 23, 2019 2:54 am UTC
by Pfhorrest
3500ft is high altitude? I can drive to that altitude from my house in 20 mins, and also drive to the beach in 20 mins the other direction.

Re: 2153: "Effects of High Altitude"

Posted: Thu May 23, 2019 7:28 am UTC
by Solra Bizna
Pfhorrest wrote:I can drive to that altitude from my house in 20 mins, and also drive to the beach in 20 mins the other direction.

So, you live in California? (The Sierra Nevadas are cheating. ;))

Re: 2153: "Effects of High Altitude"

Posted: Thu May 23, 2019 10:39 am UTC
by herbstschweigen
sotanaht wrote:I like Fahrenheit because the 0-100 perfectly measures the range of reasonably livable temperatures. 0°F (-18°C) is very cold and 100°F (+38°C) is very hot, and anything outside of that range is extremely notable.
In Celsius, 0°C (32°F) is kind of cold and 100°C (212°F) is very lethal.


FTFY. (Values are rounded to the nearest integer.) Now I can relate to the numbers a bit better. But it's just what we grow up or are used to. When your brain is used to Celsius, the -10°C to +40°C range is what I would consider "very cold and very hot, but viable" temperatures.

Re: 2153: "Effects of High Altitude"

Posted: Thu May 23, 2019 10:51 am UTC
by Sableagle
cryptoengineer wrote:The meter, btw, started out as 'One 10 millionth of the distance from the equator to the North Pole, at the longitude of Paris'. However, the Earth is more lumpy and irregular than a caesium atom. The Kilo started out as the mass of 1000 cm^3 of water at 4C.

It probably doesn't help that Paris is moving.

Celsius tends to be 1 layer of clothing per 10°, which is handy. Antarctic gear at -30, Arctic gear at -20, ski kit at -10, thick coat at 0, jumper at +10, just the t-shirt and shorts at +20, lingerie or nothing at all at +30, full-body underwear lightly sprayed with cold water at +40 and foil suit at +50.

Re: 2153: "Effects of High Altitude"

Posted: Thu May 23, 2019 12:46 pm UTC
by cellocgw
cryptoengineer wrote: However, the Earth is more lumpy and irregular than a caesium atom.


Well... from eurekalert,

. THE BUGROV-KADMENSKII MODEL For nuclei beyond the proton dripline having between 51 and 67 protons (elements antimony through holmium), the spherical model breaks down. Nuclei in this region are believed to exist only in a highly deformed shape closer to a football. Such a deformed nucleus arises when the outermost protons and neutrons move with respect to the innermost protons and neutrons.

Researchers first noticed the breakdown of the spherical model when studying proton radioactivity in iodine-109 (53 protons) and cesium-113 (55 protons). In the late 1980s, physicists V.P. Bugrov and S.G. Kadmenskii of Voronezh State University in Russia came up with a model which considers the radioactivity rate for a nucleus that is deformed. Their model yields the correct radioactivity rates for the moderately deformed iodine and cesium isotopes.


(and yeah, I'm fully aware that NIST is not using cesium for its shape but rather various radiative behaviors)

Re: 2153: "Effects of High Altitude"

Posted: Thu May 23, 2019 1:34 pm UTC
by ThirdParty
sotanaht wrote:I like Fahrenheit because the 0-100 perfectly measures the range of reasonably livable temperatures. 0 is very cold and 100 is very hot, and anything outside of that range is extremely notable. In Celsius, 0 is kind of cold and 100 is very lethal. That 0 and 100 are both arbitrary relative to water isn't really that different than how metric works in general, with such measures as the kilogram being completely arbitrary unto themselves.
This. I used to use Celsius back when I lived in a relatively temperate climate, but then I moved further north and found myself switching to Fahrenheit. Because whether the temperature is below 32°F doesn't change my day much, but whether it's below 0°F can cause me to alter my plans.

And, by the way, 0°F isn't arbitrary: it's the freezing point of salt water. That makes it a temperature that can easily be created in a lab, as well as one that's relevant to many practical questions such as "should I salt my driveway to melt the ice on it?" Also, some of my favorite body parts--e.g. eyeballs--are made of salt water.

Re: 2153: "Effects of High Altitude"

Posted: Thu May 23, 2019 1:50 pm UTC
by DavidSh
cellocgw wrote:
...Researchers first noticed the breakdown of the spherical model when studying proton radioactivity in iodine-109 (53 protons) and cesium-113 (55 protons)….


(and yeah, I'm fully aware that NIST is not using cesium for its shape but rather various radiative behaviors)


That and NIST is using cesium-133, which is stable and nowhere near the proton dripline.

Re: 2153: "Effects of High Altitude"

Posted: Thu May 23, 2019 3:04 pm UTC
by Pfhorrest
Solra Bizna wrote:
Pfhorrest wrote:I can drive to that altitude from my house in 20 mins, and also drive to the beach in 20 mins the other direction.

So, you live in California? (The Sierra Nevadas are cheating. ;))

The Sierra Nevadas are not 40 mins from the beach.

But the coast ranges are.

Re: 2153: "Effects of High Altitude"

Posted: Thu May 23, 2019 3:33 pm UTC
by Archgeek
ThirdParty wrote: 0°F isn't arbitrary: it's the freezing point of salt water. That makes it a temperature that can easily be created in a lab, as well as one that's relevant to many practical questions such as "should I salt my driveway to melt the ice on it?" Also, some of my favorite body parts--e.g. eyeballs--are made of salt water.

What molarity? Freezing point depression in a solution varies with concentration, after all.

Re: 2153: "Effects of High Altitude"

Posted: Thu May 23, 2019 3:36 pm UTC
by Zamfir
Pfhorrest wrote:3500ft is high altitude? I can drive to that altitude from my house in 20 mins, and also drive to the beach in 20 mins the other direction.

I found this graph:
Image

So, 3500ft is about the 90-10 point in population terms. Not unreasonable to call that "high", I think.

Re: 2153: "Effects of High Altitude"

Posted: Thu May 23, 2019 3:41 pm UTC
by Pfhorrest
I guess I figured that being right by the beach, our local mountains weren't actually that high up, but if Denver way up in the Rockies is only a mile high (our coast ranges get higher than that at the top), I guess that altitude doesn't really increase that much with distance from the coast like I thought it did. Though IIRC Denver it not actually up in the mountains as it is right next to the foot of the mountains, no?

Re: 2153: "Effects of High Altitude"

Posted: Thu May 23, 2019 5:02 pm UTC
by Zamfir
I checked the map, and in 20 minutes I just might make it to the mountains. In particular, a town that is non-ironically named Soest Mountain, because it is almost 30 meters over sea level.

Re: 2153: "Effects of High Altitude"

Posted: Thu May 23, 2019 9:18 pm UTC
by Flumble
Come now, 30 metres is a bit of an exaggeration. Most of it is at 20m according to the AHN. They may as well have called it Soesterdal, because the surrounding hills mountains have peaks of nearly 60m!

TIL the Veluwe really is an eyesore on an elevation map. All our other hill ranges look much more mountain-like. We'd better dig out the veluwe and use the dirt to build a real mountain near Almere like a lot of people seem to want.

Re: 2153: "Effects of High Altitude"

Posted: Thu May 23, 2019 9:55 pm UTC
by Zamfir
The village goes all the way up to the peak, don't worry. Then it become Amersfoort, where they simply call it De Berg. I once had a job on the other side, which gave a daily choice: I could cycle to the peak of the Berg and down again, or take a detour to the north and avoid the mountain range altogether. True adventure.

Re: 2153: "Effects of High Altitude"

Posted: Fri May 24, 2019 9:20 am UTC
by GalFisk
ThirdParty wrote:
sotanaht wrote:I like Fahrenheit because the 0-100 perfectly measures the range of reasonably livable temperatures. 0 is very cold and 100 is very hot, and anything outside of that range is extremely notable. In Celsius, 0 is kind of cold and 100 is very lethal. That 0 and 100 are both arbitrary relative to water isn't really that different than how metric works in general, with such measures as the kilogram being completely arbitrary unto themselves.
This. I used to use Celsius back when I lived in a relatively temperate climate, but then I moved further north and found myself switching to Fahrenheit. Because whether the temperature is below 32°F doesn't change my day much, but whether it's below 0°F can cause me to alter my plans.

And, by the way, 0°F isn't arbitrary: it's the freezing point of salt water. That makes it a temperature that can easily be created in a lab, as well as one that's relevant to many practical questions such as "should I salt my driveway to melt the ice on it?" Also, some of my favorite body parts--e.g. eyeballs--are made of salt water.

I live in Sweden, and 0°C determines whether it's wet or slippery outside, and whether precipitation soaks or cakes. The countermeasures against cold also scale quite well in 5°C increments/decrements. Also, it's just possible to feel the difference between each °C. Deicing salt also works very poorly below -12°C/10°F.
But in the end, it all comes down to what you're used to.

Re: 2153: "Effects of High Altitude"

Posted: Fri May 24, 2019 8:24 pm UTC
by gmalivuk
GalFisk wrote:I live in Sweden, and 0°C determines whether it's wet or slippery outside, and whether precipitation soaks or cakes.

Not really, because air temperature isn't ground temperature or clothing temperature.

Re: 2153: "Effects of High Altitude"

Posted: Sat May 25, 2019 6:36 pm UTC
by orthogon
cryptoengineer wrote:The meter, btw, started out as 'One 10 millionth of the distance from the equator to the North Pole, at the longitude of Paris'.

Similarly, a mile is one thousandth of the distance that The Proclaimers' Craig Reid would walk just to be the man that walked a thousand miles to fall down at your door. (Well, maybe not your, cryptoengineer's, door necessarily. But someone's door. Admittedly it's a bit imprecise and circular, as definitions go.)

Re: 2153: "Effects of High Altitude"

Posted: Sat May 25, 2019 7:14 pm UTC
by Zamfir
gmalivuk wrote:
GalFisk wrote:I live in Sweden, and 0°C determines whether it's wet or slippery outside, and whether precipitation soaks or cakes.

Not really, because air temperature isn't ground temperature or clothing temperature.

Ah, but there is a clever trick for that: you can measure those in Celsius as well!

Re: 2153: "Effects of High Altitude"

Posted: Sat May 25, 2019 10:19 pm UTC
by gmalivuk
Sure, but the point is that 0C air temperature doesn't have as sharp a meteorological significance as people often think.

Also there's the fact that it's not really harder to tell if a number is higher or lower than 32 than if it's higher or lower than 0.

Re: 2153: "Effects of High Altitude"

Posted: Sun May 26, 2019 6:01 am UTC
by rmsgrey
gmalivuk wrote:Sure, but the point is that 0C air temperature doesn't have as sharp a meteorological significance as people often think.

Also there's the fact that it's not really harder to tell if a number is higher or lower than 32 than if it's higher or lower than 0.


How many syllables do you need in order to tell whether a number is higher or lower in each case? Okay, if the person you're talking to is in the habit of describing numbers as "forty below" rather than "minus forty", it takes as long for either case, but if they start with the most significant information, it takes a single syllable to distinguish "min-", "zer-" and anything else, while "fo(u)r-", "six-", "sev-", "eight-", "nine-", and "thirty-" are all insufficient. If it's written in digits, the first symbol tells you whether it's negative or not, while 3_ could be above or below 32.

Neither comparison is exactly challenging, but comparing to a non-zero value is generally harder than comparing to zero.

Re: 2153: "Effects of High Altitude"

Posted: Mon May 27, 2019 10:29 pm UTC
by wgrandbois
Zamfir wrote:
Pfhorrest wrote:3500ft is high altitude? I can drive to that altitude from my house in 20 mins, and also drive to the beach in 20 mins the other direction.

I found this graph:
Image

So, 3500ft is about the 90-10 point in population terms. Not unreasonable to call that "high", I think.


It's not that much above the mean elevation of land on the planet (which is apparently ~840 m / 2,750 ft.) but I suppose human habitation is relevant when you're talking about cooking. Still, as someone in the 6 percent above a mile, it is a little funny. A trip down to 3,500 feet would require some planning and probably an overnight stay, while I could crest 7,000 in about 15 minutes and 10,000 in an hour. Somewhere around the latter is where I start to notice the affects of altitude on myself and the environment, so that's probably "high altitude" for me. I guess it's relative.

Re: 2153: "Effects of High Altitude"

Posted: Tue May 28, 2019 4:00 am UTC
by jgh
I don't remember how many feet there are in a mile, I remember that 64K is 65536, and the number of inches in a mile, and so the scale of a one-inch map is something a bit less than that, 63-something, and divide 65536 by 12(foot)*3(yard) to get the right looking integer that looks "12-ish", then multiply it back up again to get 63,360. Simples!

Actually, I've just noticed I should remember the palindrome 063360. ;)

Re: 2153: "Effects of High Altitude"

Posted: Tue May 28, 2019 6:40 am UTC
by da Doctah
jgh wrote:I don't remember how many feet there are in a mile, I remember that 64K is 65536, and the number of inches in a mile, and so the scale of a one-inch map is something a bit less than that, 63-something, and divide 65536 by 12(foot)*3(yard) to get the right looking integer that looks "12-ish", then multiply it back up again to get 63,360. Simples!

Actually, I've just noticed I should remember the palindrome 063360. ;)


Also a word-level palindrome when spoken, if you say "sixty-three three-sixty".

The decimally-convenient approximation of 62,500 is used for some of the topographic maps published by the US Geological Survey, those covering areas of fifteen minutes each of latitude and longitude (the other common scale, for the 7½-minute map series, is 24,000).

Re: 2153: "Effects of High Altitude"

Posted: Tue May 28, 2019 9:17 am UTC
by kuri
When it comes to measures of length or mass, the metric system deals with multiples of the basic units in an incomparably simpler manner. But regarding temperatures, I don't think that Celsius degrees are intrinsecally better than Fahrenheit (even if I think in Celsius because I grew up in a country that uses the metric system).

That's because the basic units are always arbitrarily chosen, unless you're using something like the Planck units, that are unusable in everyday life. So, the only meaningful difference IMHO (H stands for Humble :D) between the two systems is the way they deal with multiples of the basic units, and the metric system indubitably wins in this regard.

But this comparison is no more valid when it comes to temperature, because neither Celsius nor Fahrenheit have weird-looking multiple units. Moreover, both can be made more "natural" by translating Celsius to Kelvin and Fahrenheit to Rankine.

I think it is only a historical accident that the metric system came out packaged with Celsius and Kelvin rather than Fahrenheit and Rankine. But, if I was to choose which system to use for scientific purposes, I would have no doubt that meters and kilometers are more fitting than feet, yards and miles.

Re: 2153: "Effects of High Altitude"

Posted: Wed May 29, 2019 2:53 pm UTC
by AndrewGPaul
cryptoengineer wrote:
sotanaht wrote:
cryptoengineer wrote:
sotanaht wrote:>the kilogram being completely arbitrary unto themselves.


As of a couple days ago, the kilogram has been redefined in terms of physical constants: the Planck constant, the speed of light and the resonant frequency of the caesium atom: https://www.sciencealert.com/tomorrow-the-definition-of-the-kilogram-will-change-forever-here-s-what-that-really-means

That doesn't make it any less arbitrary. The Kilogram is now defined as some bullshit multiple of something that's a thousand times harder to remember than 5280, and every other metric measurement is defined as something relative to the kilogram (and also some other constant, but the measures are all meant to be based on each other). Except for Celsius, which has nothing to do with the kilogram and the only scientific merit that it has is that it's fixed points are based on water in some slightly useful way. There are no funky unit conversions to mess up the system regardless of whether you use F or C and even converting to K is pretty straightforward. You can make an argument for the practicality of metric in other weights and measures, but purely for the purpose of temperature, the two systems are equivalent.


I think we're dealing with different definitions of 'arbitrary'. The old standard for kilogram was ' the mass of a certain chunk of metal under a bell jar in Paris'. Problem was, there was only one of it; if we lost it, or it got damaged, we were SOL. In fact, its weight *did* vary against other chunks of metal which were supposed to be correct copies, and there was no way of knowing which was more correct.

The new definition eliminates reliance on a particular, arbitrary artifact. Even if every weight, scale, and other measuring device in existence was destroyed, the SI system is now defined in ways which could be exactly reproduced from written records.

The meter, btw, started out as 'One 10 millionth of the distance from the equator to the North Pole, at the longitude of Paris'. However, the Earth is more lumpy and irregular than a caesium atom. The Kilo started out as the mass of 1000 cm^3 of water at 4C.


The only reason the current definitions of the second, kilogram and metre are "arbitrary" numbers of oscillations of caesium and whatnot is so that the values match the old definitions so no-one needs to remember a whole new set of constants and buy new scientific calculators. :)I suppose we could round everything to a more easily-remembered number, but that'd be awfully confusing.