Post by srogerscat Post by Keith F. Lynch
I've figured out how to construct all the necessary components.
I'll go into detail if anyone's interested.
Okay. For those just tuning in, this is in reference to S.M.
Stirling's _Dies The Fire_ and its sequels. The premise in those
novels is that one day in 1998, electricity, firearms, explosives,
internal combustion engines, and steam engines all suddenly stop
working. Lots of people die, governments collapse, and there is
lots of medievalish warfare among the survivors.
The author later clarified that since nerves, neurons, and lightning
still work, what he meant by electricity no longer working is that
current will no longer flow in metals or in solids. All metals and
all solids have become insulators, but saltwater must still conduct.
And by "salt" I mean not just sodium chloride. Nerves require
mobility in response to electric fields of sodium, hydrogen,
potassium, calcium, magnesium, and hydroxyl ions, and probably
quite a few more.
For something to conduct, two things are both necessary and
sufficient: It must contain electrically charged particles, and those
particles have to be free to move. In metals, the particles are
electrons, and they are free to move because the valence electrons are
held in common. In saltwater, the particles are ions (atoms with more
or fewer electrons than protons), and they are free to move because
everything is free to move in water. I can imagine some entity
causing metals to stop conducting, but there's no way to get saltwater
to stop conducting without either making water a solid or making salts
insoluble, either of which would make life impossible.
The first thing that's needed is a source of power. A generator that
works by rotating a permanent magnet inside a coil of wire can be made
to work under the new rules by simply replacing the coil of wire with
a coil of plastic tubing filled with saltwater. The generator can be
turned by hand, or by animal power, or by falling water.
Plastic tubing filled with saltwater replaces wire in nearly all our
applications. We could use metal tubing instead of plastic, but
plastic has the following advantages:
* It's transparent, so we can see if there are any bubbles or debris
blocking the current flow
* It can easily be squeezed shut, to act as an "off" switch
* It can easily be bent into shape
* It can easily be cut to the desired length
* We can test these circuits under the present-day rules without
worrying about whether it's the water or the tubing that's conducting
Saltwater doesn't conduct as well as copper wire, so there will
probably never be anything like our network of power lines, phone
lines, cable TV, etc. I'm considering only small (desktop size)
For a resistor, just make the tubing narrower, or put something in it
that blocks most of its diameter.
For a capacitor, have two basins divided by a very thin non-conductor
such as plastic wrap. It's tempting to use gold foil instead of
plastic wrap as the dielectric, given that gold no longer conducts,
and can be hammered very thin. Of course that can't be tested under
today's rules, as the gold would short the whole thing out.
For an inductor, have a coil of plastic tubing, possibly with steel in
its center. This also doubles as an electromagnet. An electromagnet
can be used to make a relay, by having it open or close a "switch," by
squeezing shut some other plastic tubing.
Two such coils on a common steel core make a transformer. A coil
attached to a diaphragm, loosely around a permanent magnet, makes a
microphone or a speaker.
What about active elements, analogous to vacuum tubes or transistors?
Vacuum tubes are somewhat problematic under the new rules, since
liquids and vacuum don't mix. But I can envision a cross between a TV
picture tube and a carburetor. A tiny nozzle sprays a thin mist of
saltwater into the vacuum. The water instantly evaporates, becoming
loose water molecules, sodium ions, and chloride ions. That's the
cathode. The anode would consist of salty ice. (The author confirmed
that refrigeration still works.) It doesn't conduct very well, but it
does conduct. The grid can consist of a grid of plastic tubing. Or
instead of a grid, use electromagnets to deflect the beams of ions
toward one anode or toward another, much as the yoke coils on a CRT
deflect the electron beam to light up first one part of the screen
Since the water vapor from the cathode nozzle and from the anode ice
would be constantly tending to contaminate the vacuum, a vacuum pump
would have to be kept running all the time.
The ancestry of this tube owes something not just to the carburetor
and the TV picture tube, but also something to the klystron and the
mass spectrometer. With sufficient R&D it can lead back to the
picture tube, or to the microwave oven, or to the cyclotrons and
synchrotrons that are essential to explore the new post-Change
Fortunately, we don't need vacuum tubes for radios. If we have a
solution of some substance with physically large positive ions and
physically small negative ions, such as cesium fluoride, on one side
of a semipermeable membrane such as unglazed porcelain, and a solution
of some substance with physically small positive ions and physically
large negative ions, such as hydrogen iodide, on other side, we would
have a diode: It conducts much better in one direction than the other.
Of course these solutes would tend to get mixed together with time, so
they'd have to be continuously replenished. But that's not a major
problem, as one mole (a few grams) of +1 or -1 ions represents more
than one ampere-day.
Note that our original generator produces AC, and radios work best
with DC. Four of these diodes, together with capacitors and
inductors, are just what we need to convert the AC to smooth DC.
They're also essential to "detect" radio waves, i.e. change currents
that oscillate millions of times per second into currents that
oscillate at audio frequencies.
They can also be used as a convenient DC power source by keeping some
at room temperature and heating others over a fire, i.e. a thermopile.
To make a transistor, just add a third element to the diode. The
outer two chambers would contain P type material (e.g. a solution of
hydrogen iodide) and the inner chamber would contain N type material
(e.g. a solution of cesium fluoride). Or vice versa. Between the
chambers would be semipermeable membranes such as unglazed porcelain.
An antenna is of course just more plastic tubes of saltwater. A
ground connection is such a tube leading into a large puddle of
saltwater on the ground. Or into the ocean if it's handy.
For tuning a radio you need a variable capacitor or a variable
inductor. A capacitor can be varied by changing the shape of the
basins that comprise it. An inductor can be varied by inserting a
steel rod more or less into the middle of a coil of saltwater tubing.
That's all the components one needs to make radio transmitters and
receivers capable of conveying the human voice anywhere in the world
via shortwave. All with no solid or metallic conductors. If I had
more time, money, and motivation, I'd go ahead and build one.
I find it hard to believe that nobody would come up with such a thing
within 20 years after the Change. Especially considering its obvious
I can't see why, with further R&D, television, integrated circuits,
computers, CD players, MP3 players, etc., should not be possible.
People will be eager to recover the terabytes of inaccessible but
still existing information locked into CDs, DVDs, and hard disks
from 1998 and earlier.
Such liquid-state electronics will always be inferior to what we can
do under today's rules. But of course we haven't fully exploited
today's rules yet. So while there's no doubt that the Changed
liquid-state electronics of 2100 won't be as good as our solid-state
electronics of 2100 will be, they could easily be better than our
solid-state electronics of 2007 are.
Keith F. Lynch - http://keithlynch.net/
Please see http://keithlynch.net/email.html before emailing me.