Re: Summarry of the momentum wars and idea.

[Steve VanDevender <stevev@efn.org>]

Kevin C. Houston writes:
 > > The opposing forces are some finite amount of energy that is
 > > loaded into the system once.  Once the structure is loaded it
 > > does not absorb any more energy.
 > > 
 > > If a static structure had to dissipate energy continuously to
 > > remain standing, where would such energy come from?  Why doesn't
 > > your house fall down?  Where are the batteries?
 > 
 > good question, it actually proves my point.  consider the following 
 > experiment. (easy enough to do in reality, but a thought exp here.)
 > 
 > take a flat plate. punch three holes equally spaced along the perimeter.
 > attach a piece of wire to each hole and suspend it from the ceiling.
 > shoot (or drop) a lot of ball bearings onto the plate.
 > provided the wires don't break, the bb's encounter the plate from above,
 > but leave it (in all directions) to the side.
 > since bb's eneter the control volume every second, and leave only from 
 > the sides, the plate "feels" a net downward force.
 > provided the force does not overcome the wires tensile strength, this 
 > situation is stable. where does the energy come from? nowhere, since 
 > there is no net loss of momentum, only a change in y for a given change 
 > in x.
 > 
 > While this gedenkanexperiment <sp?> proves your point on photon thrust, 
 > (i.e. the bb's changed course)  it also proves my point on tensile 
 > forces. (the wires don't break)

Your experiment works as it does only because the momentum from
the ball bearings is transferred into the structure that supports
the plate, and because you're not including that structure in
your "control volume", you're not properly accounting for the
momentum of the system.

If you do this in space by shooting ball bearings at a plate
attached by wires to another structure, the plate and the
structure will acquire momentum and start moving as the ball
bearings bounce off the plate.

The principle of conservation of momentum that has stood since
Newton (and that was not modified by Einstein) is tricky to apply
in everyday life, because there are a lot of things that
complicate it when you're living in an atmosphere on a planet
with materials that have friction.  When you jump off the ground,
the ground also moves away from you under your feet, although by
a factor of 10^-23 less (you mass maybe 60 kg; the Earth masses
6e24 kg).  When you raise the ball bearings up to drop them on
the plate, the center of mass of the Earth moves downward just a
tiny amount to compensate.  When you drop the bearings, the
center of mass of the Earth moves back up, and counterbalances
the momentum gained by the plate attached by wires to the
structure that is sitting on the Earth.  Because this movement is
practically unmeasurable, it's easy to ignore it as you did.

In a vacuum, in zero gravity, without huge masses that make small
changes in momentum unmeasurable, we have conservation of
momentum the way Newton imagined it, pure and clean and simple.
For every action there is an equal and opposite reaction.