Having actually tried to read all of this 'debate', I want to question
Dr. Marlow on one point. While I'm on the 'they ain't forces' side of
this discussion, the one thing I don't follow (and let me be presumptuous
enough to suggest many others have not followed) is the relegating of
Gravity to a 'fictitious' force. I understand this falls out of GR
(although you can't prove it by me--despite having taken a GR course in
graduate school), but I have trouble with the inertial or near inertial
frame analysis where gravity produces an acceleration but no force!
For the sake of argument, lets make it simple and assume the earth IS an
inertial frame of reference (stop all rotations). As I sit here I still
feel the chair pushing me up (could put a scale under me and measure the
force--but I won't tell what it reads ;). However, I'm not
accelerating. Therefore, as a good Newtonian, I must assume the net
force on me is zero. What is the other force if its not gravity? If
someone suddenly pulls the chair out from under me, I now accelerate
towards the floor--again needing a force to do so--gravity? What's wrong
with gravity as a force in these situations (or have I misunderstood the
argument). Even in the GR framework, how do you reconcile Newton's laws
to this inertial frame situation?
It might work for junior and senior physics majors to deal with GR in
such situations, but for most of us (myself with Bio majors and Gen-Ed
students), it is difficult enough to get Newton's laws across WITH
gravity as a force. To try and deal with gravity as an acceleration due
to a non-inertial frame -- I don't really understand this :( -- would,
IMHO, be a disaster.
Rick
*****************************************************
Richard W. Tarara
Department of Chemistry & Physics
Saint Mary's College
Notre Dame, IN 46556
219-284-4664
rtarara@saintmarys.edu