Hi Jinx:

I believe the NZ Herald story is not correct about them being the earth's 
roundest spheres.

Why don't they just get more accurate ones from Stanford?   They are good to 
better than 25 nm (same unit as millionths of a millimeter).  See:
http://einstein.stanford.edu/content/topics/pg1.html
These can be had in a choice of fused silica or single crystal silicon.
The advantages and disadvantages of these two materials are explained on the 
above series of web pages.

They are now processing the data from the Gravity Probe-B experiment.  This was 
a direct test of Einstein's theory of General Relativity.  It's taken over 40 
years and has developed a number of new technologies.

Rather than make a physical standard I think the NIST approach to
"Replace Kilogram Standard? NIST Weighs Options"
http://physics.nist.gov/News/TechBeat/9501beat.html
is a better idea.  Just as the "1 meter" invar rod was long ago replaced with a 
much more accurate definition, as has the "second" of time.

-- 
Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.precisionclock.com

-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist