[ RadSafe ] Re: SI units

[Mark Sonter]

Deary me!

I remember as a kid learning 12 inches equals 1 foot, 3 ft equals 1 yard 
5-and-a-half yards one rod pole or perch, 16 ounces equals 1 pound, 2240 
pounds one ton, etc etc; not to mention 32 poundals one pound force, and 
something about slugs...and horsepower, BTUs, bushels, and acre-feet; 
but maybe I'm wrong.

No wonder NASA lost the Mars lander, if it was trying to work in both 
imperial and metric....

And then at university came the blessed discovery of first the cgs 
system of units and then the kgs system, now SI.

Then when I was teaching physics in Papua New Guinea, we, following 
Australia, 'went metric', and at last gallons (two types, US and 
Imperial), ounces (two types, Troy and Avoidupois), Fahrenheit, psi, and 
a host of other awful units were rendered obsolete.

Then I went off and did my Medical Physics, and learned pCi and rem, 
and, God help us, Roentgens; and then I got beaten up by a curmudgeonly 
state regulator who refused to talk in other than Bq and Sv (and rightly 
so, as SI was now enshrined in national legislation).  There were a few 
cases of mixed up units and accidentally ablated thyroids (not on my 
watch: I was counting mSv in a uranium mine..)

All I can say to our US colleagues is: try to embrace and encourage the 
transition: make it as fast as possible: other countries have done it; 
it will in the end save you immense brain energy on essentially wasted 
work; and you (and the rest of the world) will then ultimately breathe a 
huge sigh of relief.

Mark Sonter