Re: Gravity and pi

[Maurice Barnhill <mvb@UDEL.EDU>]

The committees have decreed that fm now means femtometer, which is a
unit exactly the size of the fermi.  I believe that "femto" was invented
to have fm as a plausible abbreviation.  I am sometimes tempted to tell
my students that 10^(-15) m is the femtometer, abbreviated fm, and
pronounced Fermi.

Samuel Held wrote:
> Paul,
>         I have never used the much higher (and smaller) prefixes like
> yotta/yocta and never will.  In high energy nuclear, we do use energy
> (usually GeV) for everything, since c=1 in these natural units.  For
> cross-sections, we do use barns but usually millibarns (maybe even
> smaller depending on the process).  However, for time units we use fm/c
> (or just fermi's since c=1), which makes the numbers much more managable
> and let's you see how far the particle travels.  I like it a lot.
> Everything is for laziness, oops, I mean convenience.  8-)
>
> Sam Held
>
> -----Original Message-----
> From: Paul Johnson [mailto:PJohnson@CCCCD.EDU]
> Sent: Friday, November 13, 1998 10:44 AM
> To: PHYS-L@LISTS.NAU.EDU
> Subject: Re: Gravity and pi
>
> 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.
>
> poj

--
Maurice Barnhill, mvb@udel.edu
http://www.physics.udel.edu/~barnhill/
Physics Dept., University of Delaware, Newark, DE 19716