re GR Title

[Hartwin Alfred Gebhardt]

RokyE writes:
 
> Gravity, like air, is wonderful in that you would never know it exists unless
> you were told it exists.  Invisable, ever present, great omnicent god of
> force between, for there would be no gravity if there were no other object.
> The Koan of quantum....  gravity can only be detected by it's inter-action.

A rainbow is caused, as I understand it, by the interaction of light 
and the medium it passes through. Also by our brain's tendency to 
'spontaneously' categorize a spectrum of colour into seven distinct 
colours. Gravity is the 'force' of attraction between objects with 
mass, although technically bodies are not manipulated by a force as 
such but rather by the peculiar nature of spacetime (according to 
relativity - quote attached, which could be open to criticism). But 
how does the interaction of these two terms, and the way in which 
they are related ('rainbow' belonging to 'gravity') encapsulate the 
concerns of GR (if it does)?

hg

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This is the essence of Einstein's view of gravitation. What a body does, 
it does because of the nature of space-time in its own neighbourhood, not 
because of some mysterious force emanating from a distant body. [...] The 
most interesting point about it is that it makes the law no longer the result 
of action at a distance; the sun exerts no force on the planets whatever. [...] 
The law of gravitation has become the geometrical law that every body 
pursues the easiest course from place to place, but this course is affected by 
the hills and valleys [in space-time] that are encountered on the road... 
(Bertrand Russell, "Einstein's Law of Gravitation" [originally from the 1958 
_The ABC of Relativity_]. In Ferris (ed), 1991: _The World Treasury of 
Physics, Astronomy and Mathematics_. 201/2).
hag at iafrica.com