Can’t we think of a better system than metric? I mean, a system based on water is fine and dandy, but can’t we think of something that ties in to some sort of constant, like the speed of light, the weight of an electron, or something like that? Also, can’t we get something better for time than seconds?
I’m not sure what you mean. Water is a constant. At STP, one gram of water takes up exactly one mililiter which is equivelent to one cubic centimeter.
The official definition for a meter is in fact based on the speed of light. A meter is “the distance traveled by light in a vacuum in 1/299,792,458 of a second.”
And the official definition of a second is the amount of time it takes for 9,192,631,770 oscillations of cesium to occur.
There is a better system. It’s called… Well, The American system. 
Seriously though, do we really need another system? It’s hard enough communicating with the 2 we have now. Why make another one that will probably be adopted by less than 1/3 of the countries, making it even harder to share data?
The metric system is quite versatile, and using water as one of the “standards” is about as intuitive as you can get. (The actual standard is “a weight” (a mass) in France.) One way that you could make THE SYSTEM better is if there were some sort of naturally occurring object with a very standard length. (Cesium oscillations can’t be measured with your eyes, hands and a pencil.) The only improvement I would make (having to do it over) would be to make the gram 1000 times heavier than it is, but this would just allow the gram (instead of the kg) to be more of an everyday and intuitive base measurement. I don’t think the weight of an electron is all that intuitive either and it would force us to learn many more prefixes to weight ourselves or food using the electron scale.
I’m OK with seconds, but I could go for changing minutes, hours, months and years to more of a decimal format. (This wouldn’t really change the metric system unless we actually go to megaseconds. Likely, a third system would be better for everyday usage.) (I’m OK with days (intuitive-wise), but I might be convinced otherwise with some very, very compelling arguments.)
In what instances, does the metric system not work well, but still maintains standardization? (Thumbs are intuitive, but are not standard across the population.) (I am confining this question to non-relativisticly different timeframes, of course.)
A more natural scale of measurement does exist…
the Planck scale…but its based on the fundamental physical constants of nature, which are too small to use in normal life.
i.e.
Planck mass=10^-11 gram ( molecules weigh more than this)
Planck distance=10^-32 meter (size of an electron)
Planck interval=10^-44 second (amount of time light takes to travel along the Planck distance)
Real awkward, ain’t it?
But hey, a cubic centimeter of water=milliliter=gram.
Thats a great starting point for measurement.
True, you,d have to define meter (299,792,458 M/Sec)
and second (9,192,631,770 occilations of cesium),
but that’s academic
Can’t we make it something to the power of 10? Like one millionth of the speed of light?
We came up with the second long before we knew how many oscillations of cesium it took, didn’t we? And why cesium?
“Planck distance=10^-32 meter”… Exactly? I don’t think so.
We don’t we use the Planck stuff, but start it at something useful in every day life, like starting at a Plank length times 10^32, and that would be the base unit for distance.
By the way, what are the base measurements anyway? Which ones cannot be derived from other ones? For example, a Newton is really just mass times acceleration…
So there’s mass, time, distance, temperature…
Also, for water, why doesn’t a cubic meter = liter = gram? Seems they all start at different points.
But 1 milliliter = 1 cubic centimeter of which I thought that water at STP would weigh 1 gram.
But I may have forgotten some of this through the years.
We could, but we don’t because it would make things more confusing. Ever since the meter was defined back in the late 18th century, we haven’t changed is length, just the precision by which we define it. To suddenly change the length of the meter would mean that we would have to redefine most of the derived units of metric measurement.
Again, the length of the second hasn’t changed much since it was defined, but the precision by which we measure it has. Why cesium? AFAIK, it’s because we knew at that time that cesium clocks were very accurate and could measure time with great precision.
Well you should probably understand the fundamentals of the metric system before you decide it’s not convenient. Check out this site. The base units are currently length (meter), mass (kilogram), time (second), electric current (ampere), thermodynamic temperature (kelvin), amount of substance (mole), and luminous intensity (candela).
Again, check out the site I listed above. The metric system wasn’t “based on water”, it was based on the meter. The meter originally defined both the liter (it equals one-thousandth of a cubic meter) and the gram (one cubic centimetre of water at its maximum density, 4ºC, IIRC). Arbitrary? Sure. But it was probably more useful to make the base unit of volume around the size of a present liter than a cubic meter. That’s my WAG. Anyway, IMO, the arbitrary defenitions of the base units doesn’t take away from the utility and elegance of the SI units.
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Keep your eyeballs peeled for my upcoming Staff Report on the metric system! It’s gram-tastic!
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[Edited by Alphagene on 03-03-2001 at 03:46 PM]
I’m talking about a whole new set of measurements, not a change in the metre.
We could say the same about the Imperial system. Don’t get me wrong, I think the Imperial system is much more confusing than the metric system, but can’t we think of something EVEN BETTER? Sure, it’ll be confusing for people for a while to have a new set, but in the long run it’ll be better, just like switching to metric has made stuff easier.
So basically I’m saying:
Use the Plank length, time, mass, and whatever else to make a new system. Make the units relate to each other well, unlike “1,000,000 grams of water=1 cubic metre”. And if not, can we PLEASE get rid of this Imperial crap??
Looking forward to that metric Staff Report.
OK I see where you’re going with this. It seems like the point that bothers you is the definition of the base units. I don’t think it’s terribly important, though. Would it be any more convient to define the basic unit of time as an even 10[sup]9[/sup] oscillations of a cesium atom as opposed to 9,192,631,770?
Think of it this way. If the French Academy of Sciences took this approach in the 18th Century, they would have defined the second as, let say, 10[sup]-4[/sup] solar day. The problem is, a century and a half later we developed a much more precise and uniform way of measuring time: atomic clocks.
Now in order to shift to this more precise method, we would have to do one of two things. We could base the unit of time on a power of ten of the oscillation of cesium but this would change the length of base unit of time. Alternately, we could keep the length of the traditional second and use the new method to simply fine tune the definition. You probably won’t get a round number with the new definition, but it will be consistent with the old definition and you won’t have to change the length base unit every time technology makes increased precision possible. Demanding that your base units always be a factor-of-ten multiple of a natural event unnecessarily restricts you.
The meter was originally defined as one ten-millionth of the distance from the North Pole to the equator. 100 years after the French computed this value and made it the prototype for the meter, an international committe realized that the length was actually about 0.2mm too short. The French miscalculated the quadrant from which they based the meter. Despite this discovery, the commitee kept the length of the meter as it was to be consistent. I think that by limiting yourself with what a base unit should be, you’re defeating the flexibility and ease that the metric system is supposed to provide.
Does that address your perspective?
[Edited by Alphagene on 03-03-2001 at 09:49 PM]
Shouldn’t that be coulomb, instead of ampere? Seeing as amps are just coulomb/second, it seems that amps are derived from coulombs…
Miles/Hr is derived from Miles, but Mi/Hr doesn’t measure distance, now does it?
IIRC, Current is a measure of how many electrons per second, while colomb is a simple count (number of electrons) right?
Wasn’t the original metre meant to be based on something nice and standard like the polar circumference of the earth?
Temperature is just average energy, so that’s derived. Distance is just imaginary time (and vice versa). And if you really wanted to, you could define mass in terms of distance (e.g. amount of mass required to produce a black hole with radius 1 meter= 1 black-hole-mass). So the number of basic units is actually very small.
Alphagene
While these are indeed basic units, they are not base units in the sense of being independent. I see only two (maybe three) independent units in your list: second, and ampere (and maybe mass). And I’m not sure about ampere. A mole is not, strictly speaking, a unit, any more than “dozen” or “pi” is a unit. A mole is simply a number. A very, very large number, but a number nonetheless. It is dimensionaless. Intesity is just energy divided by time. The rest I have already dealt with.
MattTheCroc
Well, a kilowatt(energy) is derived from a watt(power) and an hour(time). On the other hand, a joule-per-second(power) is derived from a joule(energy) and a second(time). Which is more valid? As long as your basic units are independent and span the needed dimensions, it doesn’t matter what they are. Amperes are easier to meaure than Coulombs, so physicists have decided to declare Coulombs the derived unit.
Mikahw
Huh?
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I was commenting on this post:
If coulombs measure Current, then Mi/Hr would measure Distance, right?
Hint: I’m saying that Colombs do not measure Current, as subtly as I can…
The coulomb is a quantity like the mole, equal to some absurdly large amount of charge?
e = 1.602x10[sup]-19[/sup] Coulombs, where e is the charge of a single proton (an electron has a negative charge of equal strength). So 1 Coulomb is the charge from 1.602x10[sup]19[/sup] protons.
Thankyou for that. I didn’t know exactly what value the aforementioned absurdly large number had.