Re: Please expand on why we feel 'right side up' on earth

I think you may be referring to a previous answer that I gave to a K-3
question about the ocean and a tea cup. In that answer, I was trying to
avoid some of the more complicated issues, and concentrate on the 
experience of gravity that we have on Earth.

So now is the chance to get to some of the more complicated issues.

First, gravity and centripetal force (force towards the centre) are one 
and the same thing. The two forces to be considered in the situations 
you describe are gravity and centrifugal force (force of flying from
the centre). Centrifugal force does not exist if you are working in an
inertial frame of reference. But it is a very real force in our everyday
lives where we work in a non-inertial frame of reference. We think of 
ourselves as stationary, rather than as doing a complicated rolling 
motion in our course around the sun. (Contrary to the way people 
usually think of it, the earth does not spin, but rolls -- motion around 
the earth's axis of rotation is much slower than orbital motion around
the sun).

Second, most of the questions you ask are not physics type questions.
They are neurological questions about how our senses, which are 
adapted to life on the earth's surface, would adapt to very different
environments, and about how our brain would choose to interpret the 
sensory input.

Third, while many of the sorts of situations that interest you can be
experimentally simulated (high gravity, low gravity, total 
weightlessness, locally inconsistent gravity), most of the actual
situations are purely thought-experiments. One would not feel right
side up or wrong side up on the south pole of a rapidly spinning
white dwarf. You would merely feel very sore feet for the millisecond 
or so before you incinerated! However, the reports of neurological 
sensation by astronauts who have experienced weightlessness, and by
fighter pilots who regularly experience G-forces which vary rapidly both
in size and direction, would provide the best experimental evidence
about the questions you are asking.

Fourth, you ask us to

'Consider a white dwarf w/ diameter of 1/2 city block.  ... I doubt that 
one would feel "right side up" if he were standing at the "south pole".  It'd 
be too small.  Or, consider a meteor a few meters long (and smaller...) that 
is a fragment of a white dwarf (and hence has GREAT density) and is 
spinning rapidly.  However, there would clearly be an "upside down" feeling 
if one were to step onto the underside of the "rock". '

How are you going to be able to tell which pole of your spinning white
dwarf is North or South? And why would you consider the South pole in
particular to be the upside down pole? For me, it would be natural to 
consider the North pole as the upside down pole, since it fits more
naturally with my own orientation. How are you going to get your 
directions to decide which side of your meteor is the top side or the 
underside. I do not think it at all clear that there would be an upside down 
feeling.

If you would like to discuss this further, it would be nice to find a 
convenient meteor, and stand on opposite sides to argue it out ;-)