🚀 go-pugleaf

ynecelc@sx.mont.nec.com (Ellison Chan) writes:

>In article <6850@tuegate.tue.nl> johan@blade.stack.urc.tue.nl (Johan Wevers) writes:
>>jdsiegel@garnet.berkeley.edu (Joel Siegel) writes:
>>
>>Yes, if it was true. But matter with a negative mass would react just
>>the same as matter with a negative electrical charge. 2 negative
>>{charged or mass} particles attract each other, 1 negative and one positive
>>{charged or mass} particle repulse each other. And negative electricity
>>doesn't give you a perpetual motion :-(

>As a matter of fact, there is such a natural occurence.
>(For the electrical case only)

>It's call the "electron-positron" pair. They are unstable and very short-
>lived. During their life, they orbit each other, but eventually annihilate 
>each other.

>However, in search for the perpetual motion machine, could not the
>ATOM be considered as such? Since the electrons are in constant motion
>around the nucleus and does not radiate away it's energy -- or does it
>have to be on a macroscopic level to be considered a machine? 

   To be useful, you have to be able to get some energy out of a perpetual
motion machine without interfering with its operation (ie. you can keep taking
energy out of it indefinitely).  There is nothing in the laws of physics which
forbids a perpetual motion machine as long as you don't want to get any
energy out of it.  The simplest example of a practical perpetual motion machine
is an object spinning in outer space.  Without any friction, such an object
will continue to spin more or less indefinitely.  This is not very useful
as an energy source, however, which is what most designers of "perpetual
motion machines" are after.
   An atom is not a useful perpetual motion machine for the same reason.  
An electron-positron pair isn't really a perpetual motion machine because the
energy you get when they annihilate is just equal to the energy that was
needed to produce the pair in the first place.  In any event, the annihilation
is a quantum mechanical event and has nothing really to do with electro-
magnetism.

				     ---Steven Leffler
					leffler@physics.ubc.ca