RE: [office-formula] Straw poll - slug (and lightyear)

["Dennis E. Hamilton" <dennis.hamilton@acm.org>]

+1

I think the SI folks have done what they can with regard to how the standard
measures have been arrived at.  Of course, if one determines the distance
light travels in one second just a little bit more accurately, we may find
that the standard meter is a bit off and we have no idea what will happen
then.  

Odds are the increase in accuracy will not contradict the value previously
in use, simply have it be more accurate but within the measurement tolerance
of the previous estimate.

What it looks like we should do is rely on the standard base units and then
use the *defined* relationships among the base units (see 4.1 in the BIPM
brochure that David Wheeler cites).  We should not make up derived
conversions but only specify the fixed relationships (e.g., 1 foot = 12
inches) that have been set and the inter-unit ones that have been fixed by
authorities (e.g., meters in feet).  Any intermediate calculations should
not be supplied or simplified by us.

 - Dennis

-----Original Message-----
From: robert_weir@us.ibm.com [mailto:robert_weir@us.ibm.com] 
Sent: Friday, April 09, 2010 08:36
To: office-formula@lists.oasis-open.org
Subject: Re: [office-formula] Straw poll - slug (and lightyear)

> 
> PS: I can also insert more exact measurements for Astronomical Unit,
> Parsec and Megaparsec if anyone is interested. 
> 

Table 5 here:  
http://www.iau.org/science/publications/proceedings_rules/units/

This is cited from "IAU Style Manual" by G.A. Wilkins, Comm. 5, in IAU 
Transactions XXB (1989) 

But the problem will be that some units, like the astronomical unit (au) 
are known only empirically.  So a new scientific paper can come out 
tomorrow and change the value at the 8th decimal place.  So do we mandate 
a specific value, based on the latest determinations?  Or leave it 
floating?  Treat it like a registry?

From a end-user perspective, I think I'd expect to use the latest values.

-Rob. 

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