Metric versus Imperial System for Diving?

[dfx]

Fahrenheit chose his "zeroes" absolutely arbitrary, then tried to tie up some physical properties, trying to justify the choices.

Both 0°F and 100°F were so vaguely defined that it didn't take long until they were redefined in terms of °C. 100°F made somewhat sense as the normal human body temperature, but due to the imprecise nature of the entire scale and the redefinition that thus followed, this isn't even true any more. The normal human body temperature is now an awkward 98.6°F. The Fahrenheit scale is not meaningful in any sense any more.

I beg to differ. People in everyday life do measure things if by that we mean intuitively. Ask someone to approximate the distance to the nearest store or school and they'll respond fairly quickly in miles. Ask them to give it to you in km and you'll get a long pause and less accurate answers. A switch to the metric system will have most people converting measurements at least for awhile until that becomes intuitive with practice. I find myself converting km to miles because km's aren't hardwired into my brain.

That is expected during a certain transition period. At least both the UK and Canada are still suffering these after-effects. But it's only a matter of time. Oldtimers may have to put up with the difficulties such a transition presents, and it is because of them that a hybrid dual system develops within the culture. To them, a new and unfamiliar system of measurements may never come natural. But give it time and the old, obsolete and cumbersome imperial units will eventually disappear. Trust the young generation to achieve that. But the transition has to be started at some point.

---------- Post added October 23rd, 2014 at 10:05 PM ----------

If America converted to the metric system how would I instantly get a read on an apprentice carpenter's skill level if I could no longer use the ole reading the tape measure test on them? Metric would be too easy and myself and every other owner in construction would lose this quick and easy barometer!

Yeah, you'd have to come up with something else. Exercises like these are nothing but a complete waste of time in SI. Indeed, if being able to read a tape measure correctly is what determines the skill level of a carpenter, then I do pity your carpenters.

 

[JohnN]

In decimal system you can add decimal points. INFINITELY MANY decimal points. So the Celcius is infinitely granular. "Metric people" wouldn't even understand that problem, because moving "up and down" to the scale is tought in elementary schools and comes natural. Moreover Celcius was chosen very logical. 0 - when water freezes, 100 - when the water boils under 1 atmosphere. Fahrenheit chose his "zeroes" absolutely arbitrary, then tried to tie up some physical properties, trying to justify the choices. Moreover when dealing with absolute zeroes scientists use Kelvin - it's just same Celcius minus 273. "Fahrenheit people" have to relearn Celcius when doing any scientific research.

People who live in imperial system have to deal with things, that don't exist for metric people. "Granularity" problem doesn't exist in metric system. You don't have to use fractions of inch when measuri ng small things. There is no need to memorize the fractions, no need to deal with 13/32 and 27/64. In metric you compare 3mm and 2mm. You need go smaller? go nanometer, go picometer. You NEVER use fractions. Just move the decimal point left or right. Going from inches to feet to miles is painful. The numbers are awkward. People who say "it works for me" never do any actual calculations, never do any scientific research, never deal with military tasks. When you do - the imperial system becomes so much trouble, that you will switch to metric whether you want it or not. In everyday life people don't convert things, don't measure things. They can live in "no system" and will do just fine.

Odd, I distinctly remember getting a degree in Chemistry.

0 oC is defined as the triple point of specially purified water. (It was a flaw in the original definition) since atmospheric pressure changes where water will freeze (and boil). The other anchor is absolute zero (which is slightly different from -273 oC).

 

[mrdre]

I beg to differ. People in everyday life do measure things if by that we mean intuitively. Ask someone to approximate the distance to the nearest store or school and they'll respond fairly quickly in miles. Ask them to give it to you in km and you'll get a long pause and less accurate answers. A switch to the metric system will have most people converting measurements at least for awhile until that becomes intuitive with practice. I find myself converting km to miles because km's aren't hardwired into my brain.

Now tell, who actually "measured" how many miles are from their home to the shop? Did you measure? Then how do you know? You just read it from your car's dashboard. You car "told" you that it's 10 miles. If your car told you it's 15 miles - you'd remember 15 miles. if it were 20 kilometers - you would remember it as 20 kilometers. Americans go to Europe and do just fine driving there and navigating. You know why? Because they treat kilometers as miles and never bother to actually measure them. You don't have to convert km to miles. In my brain they live in different cells. If it's a mile - it's a mile, if it's a kilometer - it's a kilometer. Don't convert one to another and you'll see how easy things will turn out to be. You don't have to imagine how long kilometer is, because you really don't care how long the mile is.. it's just a number..

The key advantage of metric system is that it's a decimal system. It doesn't matter how long the mile is or how long the kilometer is. What's important is that it matches the numbering system we are used to. We live in decimal system, so it makes every sense to make our measurement system to match our numbering system. It's just obvious. People in everyday's life don't measure sizes of molecules or distances to stars. They don't convert cubic miles to cubic feet. heck they can't even convert a mile to feet. If you try to do any sophisticated calculations in imperial, you will be quickly buried under lots of awkward numbers. Theoretically, you can do "everything" in imperial, but in reality the complexity of calculations (and therefore the chances of making errors) will grow so much that you will get to the point that continuing will become simply unfeasible.

 

[dfx]

One of the more hilarious aspects (well, to me, anyway) of the non-metric society that the US is, is how a lot of the gas stations present their gas prices.

$3.24 9/10

What the hell is that, a fraction of a fraction?

 

[BRT]

I have a hard time understanding people who hate the Imperial measurement system but don't seem to have a problem with the time and date system we all use. I have owned an automotive shop through the shift to the metric system in vehicles and can say without any doubt that it has not simplified things. I can stock the vast majority of o-rings in at least one rubber compound in the Imperial system but cannot even start to cover the metric ones. Metric threads have more pitches and more lengths and diameters than Imperial. Very hard to have a complete stock of metric fasteners and taps and dies. I embraced it early on because it looked simpler, but it isn't in practice.

It is interesting to me that the Japanese and Chinese want to use a "simpler" metric system but their language is written in thousands of characters. Maybe they should simplify that? Fact is you can learn to think effectively in Chinese, or in Imperial or in hours and minutes and the mind exercise may be good for you.

 

[mrdre]

Odd, I distinctly remember getting a degree in Chemistry.

0 oC is defined as the triple point of specially purified water. (It was a flaw in the original definition) since atmospheric pressure changes where water will freeze.

Duh. It has nothing to do with chemistry. Did you get your degree in wikipedia? " the Celsius scale are currently defined by two different temperatures: absolute zero, and the triple point of VSMOW(specially purified water)" - from wiki The 0 WAS CHOSEN as freezing temperature, actually Celcius himself chose 0 as boiling point and 100 as freezing. Later it became more convenient to use the other way around, and later it was understood that the boiling and freezing temperatures depend on pressure. It was in 18 century. Obviously later the corrections were made. What's your point?

If you are good at reading wiki, you can also verify this: "From 1744 until 1954, 0 °C was defined as the freezing point of water and 100 °C was defined as the boiling point of water" and that's exactly what I said - it was CHOSEN to be like that.

Now if you continue reading the same wiki, you'd see that triple point of water is not 0, but 0.01C ..

 

[JohnN]

Duh. It has nothing to do with chemistry. Did you get your degree in wikipedia? " the Celsius scale are currently defined by two different temperatures: absolute zero, and the triple point of VSMOW(specially purified water)" - from wiki The 0 WAS CHOSEN as freezing temperature, actually Celcius himself chose 0 as boiling point and 100 as freezing. Later it became more convenient to use the other way around, and later it was understood that the boiling and freezing temperatures depend on pressure. It was in 18 century. Obviously later the corrections were made. What's your point?

If you are good at reading wiki, you can also verify this: "From 1744 until 1954, 0 °C was defined as the freezing point of water and 100 °C was defined as the boiling point of water" and that's exactly what I said - it was CHOSEN to be like that.

Now if you continue reading the same wiki, you'd see that triple point of water is not 0, but 0.01C ..

Sigh. . . so here we go. . . yes a BS Chemistry University of Washington, advanced work in biochemistry. Yes it does have a lot to do with Chemistry, specifically the area known as Physical Chemistry. Yes I work with the metric system just fine. No the Celsius scale is not defined by the freeezing point and boiling point of water, absolute zero is not 273 and the meter is not a multiple of the distance from the equator to the North Pole.

Would you like to discuss the state diagram of water and why without specifying the pressure, the temperature at which water changes state is largely meaningless.

Do you really want to go there?

 

[mrdre]

I have a hard time understanding people who hate the Imperial measurement system but don't seem to have a problem with the time and date system we all use.....

Oh, I have BIG problem with time and date system we all use. Its 60 based numbering system is absolute nonsense. I think it came from China. If somebody proposed (and there were many attempts to do that in history) I'd jump right away. I'd support it even more than metric system. If you do any calculations related to time, things get messy fast.

Chinese actually did simplify, it's called "Simplified Chinese"

---------- Post added October 23rd, 2014 at 07:49 PM ----------

Sigh. . . so here we go. . . yes a BS Chemistry University of Washington, advanced work in biochemistry. Yes it does have a lot to do with Chemistry, specifically the area known as Physical Chemistry. Yes I work with the metric system just fine. No the Celsius scale is not defined by the freeezing point and boiling point of water, absolute zero is not 273 and the meter is not a multiple of the distance around the equator.

Would you like to discuss the state diagram of water and why without specifying the pressure, the temperature at which water changes state is largely meaningless.

Do you really want to go there?

I can go anywhere you want me to. Why don't you read my post more carefully? I said it WAS chosen as freezing and boiling temperatures. It WAS defined like that. I never said it IS defined as freezing and boiling temperature under 1 atmosphere (I mentioned that). What is your point? The meter IS NOT defined as 1/20000000 of meridian, but it WAS back then. What are you arguing about?

 

[JohnN]

Oh, I have BIG problem with time and date system we all use. Its 60 based numbering system is absolute nonsense. I think it came from China. If somebody proposed (and there were many attempts to do that in history) I'd jump right away. I'd support it even more than metric system. If you do any calculations related to time, things get messy fast.

Chinese actually did simplify, it's called "Simplified Chinese"

---------- Post added October 23rd, 2014 at 07:49 PM ----------



I can go anywhere you want me to. Why don't you read my post more carefully? I said it WAS chosen as freezing and boiling temperatures. It WAS defined like that. I never said it IS defined as freezing and boiling temperature under 1 atmosphere (I mentioned that). What is your point? The meter IS NOT defined as 1/20000000 of meridian, but it WAS back then. What are you arguing about?

Odd your account must have been compromised too:

You said

. 0 - when water freezes, 100 - when the water boils under 1 atmosphere

Actually the effect of pressure on the phase change of water was imperfectly understood back in the early 1700's. You seem to suffer from no lack of hubris, would you like to explain what is unusual about the phase-state behavior of water and why it is (now) an unfortunate choice for the basis of a measurement system?

And my point is you're behaving as a complete ass.

 

[mrdre]

Odd your account must have been compromised too:

You said


[/I][/COLOR]Actually the effect of pressure on the phase change of water was imperfectly understood back in the early 1700's. You seem to suffer from no lack of hubris, would you like to explain what is unusual about the phase-state behavior of water and why it is (now) an unfortunate choice for the basis of a measurement system?

This from my original post.. Don't misquote me. It's a dishonest tactic.

"Moreover Celcius was chosen very logical. 0 - when water freezes, 100 - when the water boils under 1 atmosphere. "

WAS CHOSEN. and UNDER 1 ATMOSPHERE.. I mentioned it. Print it and reread this 10 times.