Re: New artifact: The Silicon Sphere

From: J. Andrew Rogers (
Date: Sun Dec 07 2003 - 19:40:38 MST

On 12/7/03 5:16 PM, "Robin Lee Powell" <> wrote:
> On Sun, Dec 07, 2003 at 04:49:43PM -0800, J. Andrew Rogers wrote:
>> Actually, the most perfect sphere that I am aware of
> Note 'ever made by hand'. Assuming that phrase means what I'm used
> to it meaning, it makes a difference.

In both cases, highly precise automation systems would be required to
fabricate the sphere with that precision, and I assume they would use them
since reasonable facsimiles of such systems exist. The verification process
alone required a half-million spherical measurements with sub-micron
precision according to the article, never mind actually fabricating it to
that specification. A bit tedious and slow to do by hand, that. I think
they meant "man made".

>> The sphere was part of the most perfect gyroscope ever made by
>> several orders of magnitude, and it was designed to detect
>> relativistic frame dragging, which was theorized but never
>> measured until GPB. The gyroscope was designed to run
>> continuously for a couple years at 10,000 rpm with an average
>> drift of 10^-12 degrees per hour -- very impressive precision.
> How did the experiment turn out?

It was supposed to have been launched in the late '90s as I recall. Yet
looking on the web, it seems that the launch date was last scheduled for Dec
6, 2003, and I do recall hearing about a Vandenberg launch happening a few
days ago.

So ask me again in two years. :-)

J. Andrew Rogers (

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