In 1992-94 I messed around with homopolar generators, ("HPGs" or
"N-machines",) tried a simple test, and drew some GIFs of possible
devices. Check out the above links for these diagrams.
The general idea was that an HPG might lack back-torque if the
rotor and stator circuits are radially symmetrical. If all wires were
replaced with cups and tubes, would the mechanical energy per output
wattage be reduced? If this were true, conservation of energy would be
violated. The generator would create large currents and heat output, yet
it would require little driving energy. If a pair of these was hooked
together in motor/generator configuration, they might self-accelerate
anomalously and spin without extrnal energy input. Impossible by standard
physics, of course. Yet a radially-symmetric HPG does not change flux
linkage when rotating, and so it might not be expected to produce output
currents. Yet it does. Tewari and Depalma in fringe-science publications
claim to have observed anomalous behavior when investigating these
devices. If there is a way to extract the energy of the quantum vacuum
sea, perhaps here is a device which accomplishes the feat.
The pipecaps/mercury experiment was my crude attempt to detect changes
in electromagnetic braking in a shorted, symmetrical HPG. I hoped to
compare the braking forces with and without the permanent magnet present.
Unfortunately my setup didn't show low friction without the magnet, since
the oxide crust on the mercury contributed a large friction compared to
the EM braking effects. The crust/scum on the mercury gave such high
friction that I couldn't see any obvious difference between the magnet
version and the no-magnet version. To detect forces, I only relied on
twisting up the thread and making crude time measurements of the
unwinding. Later I realized that the crust could be eliminated. This
experiment needs to be repeated.
Hint for anyone who wants to try the experiment: silver-plate the copper
so that the mercury will wet it, and put light oil on the mercury to seal
it from oxygen and prevent the formation of an oxide scum layer. This
will vastly lower the friction and make the differences between the magnet
version and the no-magnet version measurable. Big hint: build a large,
heavy version of one of these shorted-out generators, spin it with a
motor, stick it in a calorimiter, and see if unexplained excess heat is
evolved. (See if the shorted homopolar generator makes more heat energy
than is input by the wires to the driving motor.)
In thinking long and hard about HPGs, I have come up with some
observations and questions. Are you confused about spinning magnets
versus spinning disks? Here's more to think about. Perhaps it will
help to clarify things.
The diagram below depicts a simplified Homopolar Generator (HPG).
Rather than using a separate external circuit and a spinning disk, I've
combined them into a two-disk arrangement. One half of the device in fig
1a is the "disk," of a classic HPG, while the other half acts as the
"external circuit." Carbon brushes connect the halves with sliding
contact. Liquid metal brushes would be better.
The two halves are placed together in fig 1b. When a magnetic field is
applied (vertical field in fig 1b) and the two halves are spun together as
a unit, the
relative motion of the metal and the magnetic field should cause a radial
voltage to appear, which causes the rim of the metal assembly to aquire a
positive charge, and the axis of the assembly to receive an equal negative
charge. NO CURRENT RESULTS, instead the device acts like a charged
capacitor as long as the rotation continues. Also, if the metal assembly
is held still and the magnets are spun instead, the same radial voltage
should appear and the same separation of charges should exist on the
object, again with a voltage only. There is a momentary separation of
charge, but no constant current.
Fig 1c shows my idea of how HPGs are able to create electric currents.
If the upper and lower halves of the device are spun in opposite
directions, the polarity of the radial voltage and the radial separation
of charges should be opposite in each disk. Since the two halves are in
sliding contact, the positive and negative regions are in electrical
contact and a very large electric current should appear. This current is
zero if the two halves are spun together. It is large if one half spins
and the other is kept still. It is twice as large if both halves are spun
in opposite directions. However, any relative rotation of the MAGNET, or
the magnetic field, should result in equal voltages radially across both
halves, and therefor should create no relative voltage between the halves,
so rotating magnets should create no current. In other words, the
magnetic field might spin with the magnet or it might not, but this cannot
be detected by the HPG disks. The HPG doesn't care if the magnet
spins. Instead, it only cares about differing rotation of the two
If you hold one half of the metal parts still and spin the other half,
you create a "classic" HPG having a spinning disk and a nonspinning
"external circuit." Simply add a current meter in series with the shaft
of the non-spinning half depicted above. You can even carve away most of
the shell of the non-spinning half and form it into "wires". You'll end
up with the "classic" HPG circuit in full.
This then shows why the rotating copper parts might apply back-action
forces against the external circuit, but need not apply any forces against
the permanent magnet. It explains the seeming non-reversibility of
current-generating action in Faraday's homopolar experiment. It APPEARS
that there is a paradox, and that the rotation of Faraday's disk generates
current, while rotation of his bar magnet does not. In reality, the only
important motion is the *relative* movement between Faraday's disk and his
external circuit, and the rotation of the magnet is unimportant. Of
course the presence of the magnetic field is necessary to accomplish the
effect and create current, but its rotation relative to the average
rotation of the disk-plus-circuit assembly only creates a net radial
charge separation without creating constant current.
Once we realize that the external circuit is the "stator" of the
device, the homopolar generator is not as weird as it first seems.
Note that these are all UNTRIED THOUGHT EXPERIMENTS. There is a small
chance that the HPG does not work as I describe above, and that there is a
true anomaly here. If the mechanical energy input to a homopolar generator
is not in perfect 1:1 proportion to its heat output, then there are
mysteries here to be investigated.
There is a chance that the device of fig. 1c will not create
back-action against whatever mechanical forces are causing it to turn. In
this case a motor could be used to spin one disk, and the current in them
would create heat, but the current would not create electromagnetic back
action, and so the motor would do no work in driving the disks, resulting
in heat energy "from nowhere." Or as with the Searle device claims, the
generated current in the disks might even create a motor action which
would spin the disks, which would create higher current but no back-action
force, which would in turn spin the disks even faster, and which would
create continuous acceleration, an explosive runaway flywheel reaction,
and again create "energy from nowhere." If you short out a radially
constructed HPG and spin it fast enough, will it start spinning faster and
faster, until it shatters from the radial forces? There are rumors that
such things happen. I haven't heard that anyone has tried this recently
and verified that nothing mysterious occurs.
I'll leave you with this though. In the diagram below, I have attempted
to sketch the electrostatic field created by a spinning disk magnet. It
seems as though there is an imbalanced charge along the rim of the magnet.
However, since charge is conserved, a region of opposite charge must
appear elsewhere. The equal and opposite charge is not on the magnet at
all, it is hanging in space along the axis of rotation! (At least
my crude drawing strongly suggests this. Am I mistaken?)
Is this real? Isn't it like those strange circular e-fields which exist
in the empty space around a toroidial AC inductor? But this is the DC
version. And I cannot see how the e-field could have these closed loops,
since the field lines seem to end in empty space at the axis of rotation.
If there were a cloud of charged particles surrounding this spinning
magnet, would the rotating field cause them to collect at the axis?
Surely simple electromagnetic physics doesn't have such a gaping flaw.
However, I've heard that in Gen. Rel., EM does not apply correctly when
the objects in question are rotating. Is this true? I don't know how to
think about this, and if I've made an error in visualizing it, I cannot
see my error. [perhaps the concept of 'lines of flux' doesn't apply to
the e-field generated by a changing magnetic field?]