From: jthorn@astro.indiana-zebra.edu   
      
   John Heath  wrote:   
   > when it comes to spinning a box from   
   > within it seems nature will look the other way if a bribe in the   
   > currency of energy is payed. Apparently the universe does not feel a   
   > need to spin counter clockwise if a box is spinning clockwise.   
      
   That's not true.  Let's pick a fixed spin axis (fixed in an inertial   
   reference frame) about which to compute angular momentum.  Among the   
   consequences of conservation of angular momentum are:   
   (a) If we spin up a box in the clockwise direction (about our spin   
       axis) then we must indeed spin up the rest of the universe in   
       the counterclockwise direction (about that same spin axis) so   
       as to keep the net angular momentum of the universe (about that   
       spin axis) constant.   
   (b) If no torques are exerted on a sealed box (i.e., no angular   
       momentum flows in or out through its walls), then the box's   
       angular momentum (about our spin axis) will remain constant,   
       regardless of what happens inside the box.   
      
   Note, however, that (b) does NOT imply that the box/s angular   
   ORIENTATION will remain constant.  For example, a free-falling cat   
   may turn her body from upside-down to right-side-up without exerting   
   any torques on the box or the outside world.   
      
   I'll say more about this latter example in a following post.   
      
   --   
   -- "Jonathan Thornburg [remove -animal to reply]"    
      Dept of Astronomy & IUCSS, Indiana University, Bloomington, Indiana, USA   
      currently visiting Max-Plack-Institute fuer Gravitationsphysik   
                         (Albert-Einstein-Institut), Potsdam-Golm, Germany   
      "There was of course no way of knowing whether you were being watched   
       at any given moment.  How often, or on what system, the Thought Police   
       plugged in on any individual wire was guesswork.  It was even conceivable   
       that they watched everybody all the time."  -- George Orwell, "1984"   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)