In article , Laurel Amberdine writes:
On Sun, 06 Jul 2003 22:35:55 GMT, wrote:

...

Before you even start getting to relativistic physics, the point
missed by many is that even in classical physics momentum *is not*
defined as mv (yes, there is quite a lot of physics beyond high school
physics). Momentum is defined as a gradient of the Lagrangian (yes, I
know this doesn't mean much to whoever didn't study it but, as I said,
there is lots of physics beyond high school physics). In the
particular case of a classical massive particle, this *evaluates* to
mv but that's a result, not a definition. For other entities you get
different result. Thus, even within classical physics electromagnetic
waves carry momentum even though they're massless.

When you're not so busy you need to write a book, Mati. Something
like "All the Physics you Learned Wrong" or something.

After all this practice you could probably write it half asleep with your
eyes closed.

Probably so, this ng is good practice for such purpose:-)

Mati Meron | "When you argue with a fool,
| chances are he is doing just the same"