|Re: A Journey into Gravity and Spacetime (& a question)
Group: sci.physics · Group Profile
Author: Brutus Date: Jul 31, 2007 01:41
On Jul 31, 2:08 am, Tom Roberts sbcglobal.net> wrote:
> Brutus wrote:
> I've not seen this book. Perhaps I'll look for it.
You must. It is light years better than Geroch's "GR from A to B"
as far as layman books for GR is concerned. It is in full color
in every page and costs only $2. The $2 1990 hardcopy edition
has exact same contents as the $54 1999 softcopy edition as
there is never a second edition so they are similar.
>> So what topics does the "boundary of a boundary" officially
>> fall under in General Relativity Proper?
> The Bianchi Identities. They are differential identities expressing
> Wheeler's statement "the boundary of a boundary is zero". This is also
> related to the generalized Stokes theorem.
> Tom Roberts
According to the book:
(Sum of moments of rotations for the faces of a little 3-cube) =
8pi x (amount of momenergy within the 3-cube)
which Wheeler called the Einstein-Cartan equation. Now
referring to wikipedia:
"Einstein-Cartan theory in theoretical physics extends general
relativity, to handle spin angular momentum correctly.
As the master theory of classical physics general relativity has
one known flaw: it cannot describe "spin orbit coupling", that
is, exchange of intrinsic angular momentum (spin) and orbital
angular momentum. There is a qualitative theoretical proof
showing that general relativity must be extended to
Einstein-Cartan theory when matter with spin is present.".
How many percentage roughly of General Relativists accept
the Einstein-Cartan theory?? 50%%? 25%%? 5%%? 99%%?