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New Book Says The Meter Is all Wrong
Bill Klemm writes "Ken Alder's new book 'The Measure of All Things' scandalizes the metric system as 'arbitrary.' CNN has a little article about a new book that explores the 'odyssey' of Delambre and Mechain to find the perfect unit of measure."
The US dosn't use or approve of the metric system, so why does it need to change the spelling?
Why do so many people get this wrong?
It is not illegal to sell goods in imperial measures. All goods sold by weight, volume or size must be priced in metric (with the exception of draught beer and cider, and milk if it is in a returnable container), but they may also be priced in imperial if the retailer wants to.
One cubic centimetre is one millilitre, no matter which way you cut the cake. Litres are a measure of volume, as are cm^3. It's just a different and more convenient name.
:)
As for water, 1cm^3 is one gram of mass at 4 degrees celsius. 4 degrees is used because it is the temperature at which water is densest. And mass is always the same, no matter what acceleration due to gravity is.
Apart from that, things look pretty good. It may also be worth noting that 100C is the temperature at which water boils, and the second milestone (odd word to use in a metric conversation) in the celsius scale, with 100 (arbitrary) divisions between freezing and boiling.
I'm amused by the fahrenheit system. Not only is it a bitch to spell, 0F is the temperature at which a saturated brine solution freezes, and 100F was supposed to be human body temperature, but I guess the guy was running a fever at the time or something
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I believe there IS a "master meter stick" kept at the same place that the kilogram mass is. It's just not used as the official standard anymore.
Now it's exactly 299792458 m/s. Nothing arbitrary about that at all.
-WolfWithoutAClause
"Gravity is only a theory, not a fact!"Who cares about hydrogen? Why not base everything off of the most basic unit possible: the planck length, time, and mass, and consequently the planck energy and every other unit. Just find some arbitrary number by which to multiply the units to some practical range (something base-10 is obvious, but maybe there is some more mathematically profound multiple, like pi, which would be more useful), and you have an entire system of measurement.
It's going to be pretty hard to get an accurate measurement of the distance across a hydrogen atom, with the Heisenberg Uncertainty Principle futzing around with that electron.
I just read this book a few days ago. The author is turning molehills into mountains.
According to the book, if Mechain had gotten his numbers right, the meter should have been longer by 2 mm. That's right, just two millimeters.
The researchers measured the width of a continent to within 0.2% of the correct value, using 18th-century equipment, in conditions that were far from ideal. (You try carrying survey equipment across a national border during a war, and see how much work you get done.) We should be impressed that they got as close as they did.
It's all a matter of units.
Energy is measured in units of force x distance. Force is measured in units of mass x acceleration (Newton's second law!), acceleration is velocity per unit time, and velocity (or speed) is distance per unit time. Putting this all together, we see that energy E has units of
mass x distance^2 / time^2
while m has units of mass, and c has units of distance/time. So the equation E=mc^2 makes sense no matter what you pick the units to be.
In SI units, mass is measured in kilograms, distance is in meters, time is in seconds, so speed of light is in meters/second. Energy is measured in kilograms-square-meters-per-square-second, more commonly known as Joules.
If we were to use light seconds and seconds, then the speed of light would be 1, but then energy would be measured in kilograms-square-light-seconds-per-square-second, which is a truly humungous amount of energy (about 10^17 Joules, which is about the same energy released by about 10 megatons of TNT, give or take an order of magnitude). So yes, the "E" in "E=mc^2" would now be tiny because c was 1, but because E is now measured in megatons of TNT the energy is still the same impressive amount. :-)