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Re: Gravity and pi



At 09:44 13/11/98 -0600, Paul Johnson wrote:
Sam

Keeping track of positive and negative exponents is sure easier than
keeping track of those latest stupid prefixes the guys in the
smoke-filled room added to the metric system -- yotta/yocto,
zetta/zepto, etc. Have you ever seen any of those used to designate
very large or very small values?

Things were better back when I was just a tad undergraduate. My
department chair (Swerwood Githens) told us that nuclear types had
their own names for very small values of area and time. Neutron cross
sections were measured in BARNS (10*-24 sq cm) and very short
radioactive halflives were measured in JIFFYS (10*-24 sec).

Only astronomers are smart enough not to fall for all this prefix
crap. Parsecs are perfectly good distance units.


Ever heard of KILOmetres per second per MEGAparsec?

Prefixes are cool. 500 nanometres rolls off the tongue so much more
smoothly than 5 times ten to the minus seven metres. And 5000 angstrom
leaves the student with the angst of how to pronounce an A with a thing on
top, as well as yet another unit definition to absorb.

Parsecs are good because they derive from angular measurement and the AU,
which need not be known accurately in metres. It's not just a matter of
preference deriving from habit.

Mark.


Mark Sylvester
United World College of the Adriatic
34013 Duino TS
Italy.
msylvest@spin.it
tel: +39 040 3739 255