Re: [Phys-l] An introduction to MTW?

[John Denker <jsd@av8n.com>]

On 02/02/2012 07:01 PM, Ken Caviness asked for:

> an introduction for physics students wanting to tackle
> Misner, Thorne & Wheeler's "Gravitation", giving extra help to get
> started.

As previously mentioned, a good background in special relativity is 
obviously super-useful as preparation for anything involving general
relativity.  See e.g.
  http://www.av8n.com/physics/spacetime-welcome.htm

Let me now add that it would be useful to have some notion of what
a geodesic is and what a geodesic does.  It turns out that you can 
do some hands-on tabletop experiments that provide a remarkably
faithful model of geodesics in curved space.  This is discussed at
  http://www.av8n.com/physics/geodesics.htm

I recently added a new section, almost doubling the size of the
document.  It discusses parallel transport of vectors, and how
this can be used to measure the intrinsic curvature of the space.
  http://www.av8n.com/physics/geodesics.htm#sec-parallel-transport

As a minor point:  The diagrams showing parallel transport along the 
surface of the earth are available as x3d (VRML) files, if anybody 
is interested.  Also the software that automagically generates the 
diagrams is available.  It's ugly code, but sometimes an ugly jump-
start is better than starting from scratch.

More importantly:  If you are even a little bit interested in general
relativity, it is worth making one of these tabletop models of curved
spacetime.  It might take you half a day to make nice darts, but it's
worth it.  I've gotten a tremendous amount of use out of my model.
It's one thing to read about geodesic deviation, but it's something
else to lay out a pair of real geodesics and watch them deviate.
Mimesis versus diegesis.

Most of the stuff in that document should be understandable to
students at the introductory college physics level, or even to
bright high-school students.  The concept of "masking tape" is
not very tricky.  (There are some more advanced bits in there,
including a delta function, but you can skip those bits if you 
want.)

They say "curved space" explains gravity.  If you understand what 
that means, you should be able to answer the following:

Quiz question:  In /what direction/ is the space curved?

Trick question:  Consider the ordinary local gravitational field,
 which we take to be uniform on the laboratory scale.  /How much/
 curvature does it take to produce this uniform field?  In other
 words, approximately what is the radius of curvature?