I've been finding a lot of popular press coverage distressing. Maybe I should
keep some sort of journal of my specific objections.
Here are a couple of bad habits which come to mind:
- not understanding or mentioning historical context
- presenting (or being aware of) only one side's position in a conflict
- being visibly impressed by power or capability, without discussing
where it came from, or whether or how someone else could acquire it
- assuming that a particular event will happen
- projecting trends without explaining the basis for the projection;
perceiving historical inevitability; ignoring the existence of
conflicts
- editorializing about people or groups not in a position to complain
about how they're characterized
- trying to fit people and ideas into familiar categories even where
they're importantly different from what a reader is familiar with
- adopting a prejudice or stereotype without commenting on it
- ignoring a diversity of motives among people who do some particular
thing
I got to celebrate the new year in Massachusetts with Eric and Kate, for
what I think was my eighth straight year celebrating with Eric. I also
saw a bunch of cool people whom I rarely see except at Eric's new year's
party, and got a visit from Rachel and Vasilios, who graciously drove for
hours and hours.
I did a countdown program in Python, using Tkinter. It's normally done
with HyperCard, but Eric couldn't get HyperCard running right away, so
I tried out Tkinter. I have to admit that I don't know an enormous amount
of Tkinter, but it's pretty straightforward to get started with it. The
most difficult part is probably the geometry management and packing
stuff.
We thought we might be able to get the countdown to start a fire (as we'd
hoped in previous years) -- lighting a candle, for example. Unfortunately,
I couldn't get my solid-state relay to trigger from my laptop's parallel
port, and I didn't have a voltmeter or LEDs or anything else to use for
debugging purposes. So the computer control was out this year. We did try an
experiment later on to see about the possibility of igniting something
with electricity. Our experimental result is this: if you connect eight
9-volt batteries in series (which is very easy to do because of how the
connectors are designed), a fairly large spark is produced by the 72-volt
potential across the resulting gap when battery leads are brought close
together. This spark is sufficient to ignite a small piece of cardboard
wetted with 91% isopropyl alcohol.
A much simpler technique would be to get a thin wire like those used in
cigarette lighters in cars, and connect this to a relatively small DC
voltage. The wire should become hot enough to ignite things (like
cigarettes). There is some detail about matching the internal resistance
of the power source in order to maximize the power dissipated through
the wire.
The theory here is pretty simple. Suppose that we want to cause heat by
connecting a wire in series with a battery. Assume that the battery's
total voltage is V, and the internal resistance of this source is Rs, the
resistance of the wire is Rw. Then the total series
resistance is Rs+Rw, current I=V/(Rs+Rw), power in the wire
Pw=I*Vw=V^2*Rw/(Rs+Rw)^2. I did take dPw/dRw by hand (I'm ashamed to
say it's the first derivative I've taken in a year or two), and
found it to be V^2[(Rs+Rw)^2-2Rw(Rs+Rw)]/(Rs+Rw)^2, which has a zero
when Rs=Rw. This implies that the wire will become hot most quickly
when its resistance is exactly equal to the internal resistance of the
battery.
(In that case, of course, the battery will also dissipate power at
the same rate as the wire, so the battery may become rather hot as
well.)
There's a much more general result, or technique, known to
electrical engineers, and it's called
impedance
matching. I never got far into alternating currents in my
physics class, so I didn't learn too much detail about impedances.
I'm glad I got to be here for the new year. I'll be back in
California soon.
Happy new year!
