Metric babies

My friends had a baby today.  Congratulations to them!  And congratulations especially to Dave, for announcing the baby’s mass in kilograms.  I can’t understand why society insists that baby announcements should always be in outdated imperial measurements.

Sensible people use the metric system (or SI units, after the full French title: Système international d’unités) because it is far superior, and it is superior for two very good reasons:

1. The base units are defined by specific quantities are always the same, no matter who measures them, or where, or when.  (Except, crucially, the kilogram.)
2. The larger and smaller versions are all related by multiples of 10, allowing for easy conversion.  It’s easy to convert 1.234 kg to grams, but how many ounces are in 12 stone 6?

“Yeah, but they’re so easy to visualise”, people say, “and metric numbers are so cold and clinical”.  What a load of woolly nonsense!  Whose foot?  Which stone?   And where is the problem with visualisation?  Try this on for size:

Baby Zoë was born at 583144929491543703900 +/- 275778953100 periods of the transition between the two hyperfine levels of the ground state of the caesium 133 atom since an arbitrary datum chosen by medieval monks.  She has a mass of 3.24 times the mass of a cylinder of platinum-iridium alloy stored in a lab outside Paris.  Mother and baby both have heart-rate, blood pressure and temperature within one standard deviation of the mean of their cohort.

See?  Much better!

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1. p.s. Their temperature was around 37 hundredths of the difference between the freezing point and boiling point of pure water at sea level above the freezing point of pure water at sea level.

p.p.s. I’m not sure how tall the wee lass is, but it is probably between 0.45 and 0.55 times the distance that light travelling in a vacuum covers in 9192631770 periods of the transition between the two hyperfine levels of the ground state of the caesium 133 atom.

p.p.p.s. 583144929491543703900 periods of the transition between the two hyperfine levels of the ground state of the caesium 133 atom is roughly, but not exactly, 2011 orbits of the Earth round the Sun, plus 4 orbits of the Moon round the Earth, plus 15 rotations of the Earth, plus 9 24ths of a rotation of the Earth, plus 34 60ths of a 24th of a rotation of the Earth, since an arbitrary datum chosen by medieval monks.

p.p.p.p.s. …and I don’t know why she swallowed the fly…

2. Anthönie Edward Wain says:

The Main Market Square in Kraków, Poland, is approximately 200 times the distance that light travelling in a vacuum covers in 9192631770 periods of the transition between the two hyperfine levels of the ground state of the caesium 133 atom.
by 200 times the distance that light travelling in a vacuum covers in 9192631770 periods of the transition between the two hyperfine levels of the ground state of the caesium 133 atom.

Which makes it awfully big.

Anthönie

• Just 13 60ths of a 24th of a rotation of the Earth since the original post. That’s swifter than I had anticipated. Good work.

3. Excellent! As an American, I have to say that I was flabbergasted to learn that Brits still talked about weights in stones. It’s the one place Americans have actually got ahead in eliminating unintuitive measurement schemes.

4. Matt Hall says:

Like! But I don’t know how convincing your example is… I would go further than ‘sensible people’ — scientists use SI units.

@Anne: LOL, you’re kidding, right? You can’t ambush the innocent little stone and use it to feel better about the unit craziness in the USA 🙂 Maybe I see the worst of it in the oil and gas business, where I have witnessed things like kft (kilofoot!), barrels per sq km, and degrees Rankine (degF transformed onto the absolute scale).

5. Gaz Morris says:

Much better, but perhaps a little verbose?

Like most things, it’s just whichever convention that you’re used to. I remember that my maths teacher for my third year of high school (ages 13-14) was astounded that most of us would use the SI units for maths and physics but weigh and measure ourselves in ‘English’ units.

The reverse of this was when for one of our final seismology practicals, we were given an old American section. The horizontal scale was in nautical miles, whilst the vertical was in ‘Mega-feet per second’. Our lecturer was surprised that we didn’t know how many feet were in a nautical mile.

Like most people (I hope), I have trouble converting some units on the fly so I use approximations. An English pint is 568ml, but it’s easier to easier to approximate it to 500ml. I was at a bit of a loss once when trying to adhere to the speed limit posted in miles, whilst driving a car with a speedo only marked in kilometres.

There’s a useful unit converter here.

6. Rustynailer says:

Measurement has to be perfect and complete, I am on the side of imperial until I see a date and time in metric. Metric is not so perfect or complete.
Start with 7 days in a week or even 24 hours in a day, the conversion to base ten would give errm… 100 hour days? How many days in a week?

• I don’t have problem with 100 hour days in principle. There is no reason for a second to last the length of time that it does. We only have 60 of them in a minute (and 360 degrees in a circle) because the Sumerians loved base 60. Base 60 numbers might be handy because they can be divided up so easily, but I don’t think that this is a problem for base 10 because the fractions are easier to deal with.

Some high-level programming languages e.g. Matlab, Python, use the day as their main unit of time. Thus 123456.25, 123456.50, 123456.75 represent 06:00, 12:00 and 18:00 on the same date. It is quite intuitive once you get used to it.

That said, a 1000 day year wouldn’t make much sense, because it would bear no resemblance to the orbit of the Earth or the seasons.

• Rusty Nailer says:

You have hit the nail on the head there John, those high level programming languages, time has already been metrified(!) and I did not realise. At least for us in general it will probably stay unchanged, for sanity’s sake. I concur a 100 hour day is not a problem at first glance.

7. My father, a physics teacher, insisted that my weight be recorded in Newtons. I bet the nurses thought he was nuts.

8. Iceman says:

LOL awesome post! In India, we are taught as kids to use the Metric system and everyone finds it very comfortable actually. If you walk up to to someone and ask for a pound of sugar, you will get no sugar, but just a blank stare for 2 minutes.

@Julia
doesn’t a 2.4KG baby weigh roughly 24 N ? 😛

9. Constance rose Silvertop emersonski Boyle the third says:

I’d forgotten that Zoë’s birth had been immortalised on the world wide interweb. I’m pleased to report that she is 115 centimetres tall which (crucially) permits access to most of the rides at disneyworld Orlando. Who record their height restrictions in inches….