Peter wrote in message news:qA0Qa.46717$ye4.35832@sccrnsc01...
out2lunch wrote:

I stand corrected. Very clever. The key here is that the body must
be composed of two disjoint parts that can rotate freely in opposite
directions. If I were floating by myself in space, there's no way I
could perform this maneuver.

Sure you could. For example imagine yourself floating in a
'standing posture' and start by keeping your legs straight down
but put your arms out to the sides. Now the upper part of your
body has a higher moment of inertia than the lower part. Twist
about your stomach so your legs are rotated 90 degrees to the
right relative to your arms. Most of the rotation will be of the
lower part of your body to the right with only a little rotation
of the upper body to the left due to the greater inertia of your
upper body. Now pull your arms in to your sides but extend your
legs out (like doing a split). When you untwist your stomach
most of the rotation this time will be of your upper body to the
right with only a little leftward rotation of your lower body,
which now has the greater inertia. Finally put your legs
straight down again and you'll be in exactly your original
configuration but rotated to your right.

You speak truth. I'm converted!

The weird thing is that by flapping your arms and legs and twisting
your stomach back and forth quickly, you can spin in space, yet never
have any angular momentum! The lesson for me here is that an overall
nonzero angular velocity does not necessarily imply a nonzero angular
momentum. If the spinning person doubts this, all he has to do is
stop flapping and twisting and, lo and behold, he stops spinning. No
momentum!

Thanks guys. I love it when I'm wrong, which means I enjoy life
almost constantly!