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New Book Says The Meter Is all Wrong

Posted by timothy on from the humane-fahrenheit-inhuman-celcius dept.

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."

3 of 315 comments (clear)

  1. To be strictly accurate.. by WolfWithoutAClause · · Score: 3, Informative
    The definition of the meter ISN'T arbitrary. It was arbitrary.

    Now it's exactly 299792458 m/s. Nothing arbitrary about that at all.

    --

    -WolfWithoutAClause

    "Gravity is only a theory, not a fact!"
  2. Yes it's wrong. But not by much. by AuraSeer · · Score: 3, Informative

    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.

  3. Re:Can someone explain one thing about metric unit by teorth · · Score: 3, Informative
    am I to believe that the meter/kilometer just happens to be the right size to express the speed of light (c)? And what if we measured things in light seconds or in light years?

    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. :-)