Re: [asa] Cameron- question of Adam - cosmic ref frames

From: Dave Wallace <>
Date: Tue Jun 30 2009 - 16:46:10 EDT
George Cooper wrote:
Hi George,

You said:  The "in principle" legitimacy of all coordinate systems of course
doesn't mean that some aren't better than others for specific problems.  But
retrospectively we can see that a fixed-earth frame is as good as a
fixed-sun one.
I vaguly remember in my engineering statics and dynamics courses that the possibility of geocentric vrs heliocentric coordinate system was given as an example of a possible co-ordinate transform, although the resulting equations were unusable without computer assistance.

Re virtual and real particles
As a computer programmer we use virtual memory all the time and the difference  between real and virtual memory only matters when one is doing kernal operating system programming or when performance issues are involved.  Thus for someone with my background virtual vrs real particles does not seem to make much of a  difference.  I understand it makes more of a difference in the physics world. 

Dave W
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