Conference noted::sf

Gee, you weren't reading the latest _Scientific American_ just before you wrote
this note, were you?  There is an article in it discussing the contents of a
vacuum (a vacuum being a region of space where everything that can be removed
has been removed).  It seems there will always be electromagnetic energy in a
vacuum.  In fact, the article claims there is an _infinite_ amount of energy in
a vacuum (of non-zero size, of course).

Remember the Sheffield story I mentioned, the one where energy was obtained
from the vacuum?  (I believe I gave the title of the book the story was in, but
not the story title itself; it is "All the Colors of the Vacuum" or something
similar.)  It seems Sheffield's hypothesis was right on the button!  Now that's
science fiction.

One problem is that Sheffield is taking energy from the vacuum, rather than
just letting it sit there.  Part of the article in _Scientific American_
suggests it is not possible to obtain this energy.  However, another part
gives a thought experiment which seems to suggest it is possible.  The
experiment is this:  Attach an electron to a spring.  This gives a harmonic
oscillator.  Apply an impulse to the electron, the leave the system alone.
Without the energy of the vacuum, the electron will move back and forth at
a frequency dependent upon the spring.  In so doing, the electron will radiate
energy in the form of electromagnetic waves.  This will damp the vibration.
Eventually, the electron will approach rest (relative to the fixed end of the
spring).  But it turns out that the energy of the vacuum will impart random
forces upon the electron, and its average energy is non-zero, no matter how
long the experiment continues.

Well, if the electron is radiating energy forever, why don't we pick it up and
use it for something? 


				-- edp

I think this sort of thing was also the power source Heinlein used in
the denouement of "Waldo."

re .1: "why can't we attach a spring to a electron and collect the energy
produced by zero-point vibrations?"

Hmmm, for that matter, why don't electrons radiate as they orbit atoms? Some
quantum mechanical effect no doubt prohibits it.  Eg, electrons are only allowed
to have discrete amounts of spin, so radiating incremental amounts of energy is
forbidden.  Does someone out there know for sure? The same effect would probably
keep one from getting perpetual motion out of sprung electrons. 

We already do know about one form of energy that permeates all space: the
four degree background from the Big Bang.  Why not put out an antenna with
a diode on it and rectify it to DC?  Because the antenna radiates as much
or more as it receives.  The antenna itself has a temperature and therefore
a thermal output.  In order to radiate less than you receive, the antenna
must be colder than what it's picking up.  Cooling the antenna below the
ambient temperature needs a refrigerator, and so the second law of
thermodynamics wins again.

/jlr

Re .3:

I agree that quantum effects may prevent the electron from vibrating forever.
However, there is an infinite amount of energy present; if the spring has a
different spring constant (viz., it is more or less difficult to pull or push),
a different frequency of energy will affect the electron.  By selecting the
proper frequency, any desired amount of energy can be imparted to the electron,
in an ideal situation (although I bet some fairly extreme spring constants
would be involved).  This would overcome quantum effects. 

The analogy to the temperature of the universe does not hold; it is finite. 


				-- edp 

If you are looking for "free" power, simply go to the North Pole, plant one
end of a 30 million-to-1 gear reduction train into the ground, put a high
speed 90 degree gear spline on the other end, and put a gyroscope wheel on
the end of the gear spline.  Start the gyro spinning at a little more than
20K RPM.  Now the gyro is 90 degree to the Earth's axis and will be "powered"
by the Earth as it rotates under the gyro.  Bring lots of lubicants...


John B.

Re .5:

Could you provide an illustration or explain your setup more?  How is the
reduction train anchored?  How will precession affect the gyroscope?


				-- edp

If I follow this right, the gear train is just mounted on the earth.  The
gyroscope is mounted in a way that lets it swing freely.  The gyroscope will
always try to point in the same direction but the earth will turn beneath it.
Some precession will be imparted to the gyroscope by its mount.  If the
gyroscope precesses at the same rate that the earth turns, then nothing is
gained.  Perhaps a little motor could be built into the mount to counteract
the frictional forces. /jlr

Re .6 and .7:

I'm sorry, but I meant .5 as a bit of a joke... I don't think it will work.
The gear train works both ways so that the gyro might just spin around the
North Pole and eventually stop.  it was one of those perpetual motion machines
that just didn't pan out...


John B.

Oh no, snookered!  Actually, it is possible to extract energy from the Earth's
rotation; witness the Foucault pendulum.  In the course of 24 hours it turns
around once. There ought to be some easy way to extract the energy because
there's a hell of a lot there.  Some quick integration shows that: 

kinetic energy of a rotating sphere of constant density =

density * (rotational velocity)^2 * (pi)^3 * (radius)^5 / 20

If the Earth has a radius of 6.4 million meters, and a density of
five thousand kilograms / m^3, then the energy in the Earth is
4.4 * 10^29 joules.    That would meet the electrical needs of the US for
thirteen billion years.  And what does it do now?  Sloshes up tides!
What a waste.
/jlr

Re .9:

> Oh no, snookered!  Actually, it is possible to extract energy from the Earth's
> rotation; witness the Foucault pendulum.

What makes you think a Foucault pendulum turns?  Because you can stand and
watch it go around?  Are you sure the pendulum is turning?

> In the course of 24 hours it turns around once.

I do not believe any Foucault pendulum has turned around once in 24 hours;
nobody, as far as I know, as ever erected one at a pole.

Anyway, we do not need to travel to a pole to extract energy nor construct any
fancy devices.  Simply ways of extracting energy from the Earth's rotation
are already being used.  Here is one:

	Take a harbor (but do not take it too far, the government
	might get angry).  Build a dam between the harbor and the ocean.
	Put turbines in the dam.  When the tide comes in or goes out,
	let the water turn the turbines and generate electricity.


				-- edp

Re .10: 
I'm afraid I don't follow your first comment.
Sure the pendulum is turning, or to be more precise, we are turning
relative to the pendulum's plane of swing.
A mechanism for getting energy out of it wouldn't
be too complicated.  Imagine attaching a magnet to the pendulum, and having
another magnet on a ring-shaped track around it.  As the pendulum turned
it would drag the track magnet around with it, which could be hooked to a
generator.

It's true that Foucault pendulums don't turn around in exactly 24 hours.
The period turns out to be 24 hours divided by the sine of the latitude.
At the equator it wouldn't turn at all.

Tidal power is a promising energy source.  The last I heard, they were still
working on the environmental problems of a big station in the Bay of Fundy
in Nova Scotia.  Right now they're trying to model the effect on ocean currents
all up and down the New England coast.  Interestingly enough, the Back Bay
in Boston used to have a mill run by tidal power.  The Charles River used
to be an estuary at that point, and the mill would run by tapping the tides
as they flooded into the Back Bay swamp.  That all ended, of course, when
they filled it in with condos and art galleries.

/jlr

Re .11:

> Sure the pendulum is turning, or to be more precise, we are turning
> relative to the pendulum's plane of swing.

As you point out, it is we who are turning (in an inertial frame of reference).
The pendulum merely swings back and forth without turning.

> A mechanism for getting energy out of it wouldn't
> be too complicated.

Since the pendulum is not turning, you cannot extract any energy from its
rotation.

> Imagine attaching a magnet to the pendulum, and having
> another magnet on a ring-shaped track around it.  As the pendulum turned
> it would drag the track magnet around with it, which could be hooked to a
> generator.

The major result of this would be to put energy _into_ the pendulum.  Also,
the force exerted on the generator would be transmitted to the Earth, which
would cause the Earth to slow down a little.  This is where the energy to run
the generator comes from.

Problem:  Would the above situation result in the pendulum eventually absorbing
rotational momentum to the point where it turns at the same rate as the Earth,
causing the generator to stop, or would the generator run until the Earth
stopped rotating? 


				-- edp

Why not just tap the ionosphere ? Lots of energy there; "run" a line
from the ionosphere to your power station, "massage" as desired and
voila' ! 'Course, you gotta watches those short circuits...

Murray Leinster did just that in his "med ship" series.  What I was
talking about was something else that hasn't (yet) been discovered
because of its subtleties.  

And of course, *too* muck mucking around with the ionosphere might con-
ceivably have some effect on the Ozone Layer....

Steve Kallis, Jr.