In order for a ghost
to be magnetic, the ghost needs to have a negative pole and a positive
pole, and energy going from one pole to the other around him. Any iron
or steel object caught in that field will be attracted to him. He could
also be completely positively charged or negatively charged. And it is
by coming into contact with something charged negatively or positively,
depending, that suddenly a repulsive or attractive field could be created,
pushing objects around.
A fundamental physical law is that energy is conserved:
the total amount of energy never changes. This can be understood as energy
never being lost or gained, only transformed somehow. Equivalently, energy
may be gained or lost locally, but this change is always exactly compensated
elsewhere. Because of this conservation, energy is equal to minus the
gradient (the vector of derivatives to different variables (e.g. axes))
of force: the larger the change in force, the higher the energy being
stored and used, but in the reverse direction. If moving an object in
direction x costs force, energy in the reverse direction is being built
up and energy in the same direction is being lost. For example, consider
stretching an elastic band that was at rest. More force must be applied
the further the band is stretched, in other words, more work is done in
the final centimeters than the first few. The energy supplied by muscles
is being expended to do work in the same direction as the muscular force.
Simultaneously, the potential energy of the elastic band is being increased,
in the reverse direction to the muscular force.
After work is done, the accelerated object contains
kinetic energy: it can itself cause work in another object, by bumping
into it. A well-known example of this is the collision of one snooker
ball with another. Due to the conservation of energy, if energy causes
work, and hence a new cause of work, it becomes less able to cause even
more causes of work; locally, and in a specific form, the energy is reduced.
A snooker ball does not go on and on colliding, but loses its ability
to cause work. Imagine the alternative - the ball would never stop, neither
would the balls it hit, neither would the balls they hit, and so forth.
The faster and more massive an object is, the more kinetic energy it has,
and has taken from another energy source.
So, we have two kinds of energy, potential and
kinetic energy. Potential energy can be transformed into kinetic energy;
in other words, potential is that which can cause movement. Kinetic energy
can be transferred: movement can cause movement. And so forth. The discussion
of the membrane potential will focus on the transformation of a kind of
potential energy into a certain kind of movement.
Quantum effects
Technically any body sitting on a surface is levitated
a microscopic distance above it. This is due to electromagnetic intermolecular
forces and is not what is really meant by the term "levitation".
Because of the small distances, quantum effects are significant but Earnshaw's
theorem assumes that only classical physics is relevant.
If you can detect the position of an object in space and feed it into
a control system which can vary the strength of electromagnets which are
acting on the object, it is not difficult to keep it levitated. You just
have to program the system to weaken the strength of the magnet whenever
the object approaches it and strengthen when it moves away. You could
even do it with movable permanent magnets. These methods violate the assumption
of Earnshaw's theorem that the magnets are fixed. Electromagnetic suspension
is one system used in magnetic levitation trains (maglev) such as the
one at Birmingham airport, England. It is also possible to buy gadgets
which levitate objects in this way.
Electrostatics
It is also possible to move an object by using
an electrostatic field. An electrostatic field that attracts ions toward
a common centre, a radial field, will also exert a focusing action on
a divergent beam of ions. The radius of the arc traversed by the ions
will be proportional to their kinetic energy.
Sonic Waves
Certain electromagnetic fields can also act as
carriers for sonic waves which might be able to move certain objects.
|
