Re: Earth expansion - parameters for discussion

From: Aidan Karley (aidan_at_mynameplus1.demon.co.uk.invalid)
Date: 01/01/05 

Date: Sat, 01 Jan 2005 16:00:07 GMT

In article <41d46f35$0$45620$ed2e19e4@ptn-nntp-reader04.plus.net>, Ian
Stirling wrote:
> Billiard balls are shiny, big scratches would be obvious.
> They are what, 6cm in diameter?
> So that'd make .2mm relief.
> That's enough to be perceptibly rough.
>
       As anyone who has tried to make an astronomical mirror (or
polish a rock) would tell you, you can make a glaringly obvious scratch
with a grit particle a *lot* smaller than 0.2mm ; in the final
pre-polish stage, a single grain of 400 or 600 grit can leave a scratch
which under the microscope looks like an aerial photograph of Clapham
Junction after the bombing.
       Remember the issue of separation between the high and low points
of a "rough bit" : on Earth the relief is between the Marianas Trench
and Everest, which is ... (40 degrees of longitude @ 30N on radius
6370km) ... about 4000km. But let's look back at the latitude/
longitude - the 0.2mm surface roughness will be spread across about a
eighth-turn of the ball. Are you sure that you would notice that? I'm
not.
        

-- 
 Aidan Karley,
 Aberdeen, Scotland,
 Location: 57°10'11" N,  02°08'43"  W (sub-tropical Aberdeen), 0.021233

Relevant Pages

  • Re: Earth expansion - parameters for discussion
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