Monthly Archives: July 2003

Holy Rat Brains, Batman!


Today, the BBC is running an article entitled Rat-brained robot does distant art. The idea is that a collection of 50,000 rat neurons in a petri dish at Georgia’s Institute of Technology is controlling a robotic arm at the University of Western Australia in Perth, and directing it to make drawings.

Does this seem just the teensiest bit strange to people?

The scientists describe the rat-brain as ‘semi-living artistic entities”. Somehow this conjures up the image of Vincent Van Gogh’s zombie corpse, staggering around chanting alternately “Brains…” and “Crayons…”.

Of course the real question is “who is funding this mad science, and how can I get in on it?”. Perhaps this technology could be applied to making sharks with frickin’ laser beams attached to their heads.

You can check out more on this project at the MEART webpage.


Quine in Python

I’ve been trying to hone my Python skills. Python has lots of nice commands for manipulating text, including standard libraries for doing base64 encoding. After a few abortive tries, I came up with.

#!/usr/bin/env python
data="""
aWYgX19uYW1lX18gPT0gJ19fbWFpbl9fJzoKICAgIGltcG9ydCBzeXMsIGJhc2U2NAogICAgc3lz
LnN0ZG91dC53cml0ZSgnIyEvdXNyL2Jpbi9lbnYgcHl0aG9uXG5kYXRhPSIiIicrZGF0YSsnIiIi
XG4nKQogICAgc3lzLnN0ZG91dC53cml0ZShiYXNlNjQuZGVjb2Rlc3RyaW5nKGRhdGEpKQo=
"""
if __name__ == '__main__':
    import sys, base64
    sys.stdout.write('#!/usr/bin/env python\ndata="""'+data+'"""\n')
    sys.stdout.write(base64.decodestring(data))

(You can download the code directly from here.) It’s very similar to one of my early C quines, but significantly shorter, and somewhat easier to follow.

For other good links on quines, try this page of quines, or perhaps this list of quines in many programming languages.

Happy Birthday to BrainWagon!


As is typical of males, I forgot a birthday! As of July 21, BrainWagon celebrated it’s one year anniversary.
Huzzah! Let the kegs of ale burst asunder, and let there much munching of delectable meats…

In the past year I’ve managed 141 entries, most of them about silly stuff. To anyone who reads this, I hope that you are enjoying it. I’ve been slacking a little bit as of late, but I’ll try to get back to putting some interesting links shortly.

Till then, have a slice of cake and put on a silly party hat.


More cool IR stuff…



I’ve been experimenting with digital photography using my
Nikon 4500, and have took some kind of cool pictures. The palm on the right was shot with a Wratten 89b in bright daylight. A little photoshopping, and it looks pretty nifty.

Anyway, I’m constantly on the lookout for new links, and ran accross SCIENCE HOBBYIST: Ten dollar Infrared Goggles, which is by that cool amateur science guy Bill Beaty. He’s got all sorts of interesting science links, and in this one he shows how you can make decent IR filters from inexpensive theater filter gels.

Shuttle Musings…


Today,
Slashdot is reporting that the
BBC has announced that recent investigation of the Columbia disaster has shown that the foam that blew off and contacted Columbia’s wing could have resulted in damage consistent with the
catastrophic loss of the spacecraft.

In the test a 0.8kg piece of foam was fired by a nitrogen powered gun at a panel that was decommissioned from Atlantis. It contacted the wing at 850km/hour, and blew a 40cm square
hole.

Immediately the "cogniscenti" of slashdot set up a huge cry that such a large velocity
was unwarranted: that there was literally no way that the piece could have accelerated to such a
high velocity in such a short span of time. Most are just ignorant assertions, but some people try
to do the math, such as this one:

As far as I can see, I’d imagine that the foam falls from the fuel tank/booster onto the shuttle wing. The rate of fall should be only the relative acceleration that the shuttle experiences during the fall. (Since both foam and shuttle are presumably moving at the same speed when it detaches from the launcher)

So the total acceleration should be the acceleration of the shuttle (max 3G at liftoff according to a couple of web sources) plus normal gravity – call it 4 G. At most, the foam could fall the full 56 meters of the shuttle/booster/tank height (and most likely substantially less than that).

So, a quick (and probably hideously wrong) calculation based on v^2=2 * Accel * Distance shows that the end velocity of a body falling 56 meters at 4g should be about 33 meters/second, or 119 kph (74 mph)

Of course, the factor that they are missing is the enormous drag caused by the very unaerodynamic chunk of foam insulation as it detaches from the tank. The relatively low
mass and high drag of such a chunk causes it to decelerate very rapidly.
When the insulation disconnected, Columbia was 81 seconds into its flight, travelling at
Mach 2. Initial estimates indicated that the impact speed could not have been more than
500mph.

But do the math! At a relative speed of 500mph, a 1kg chunk of insulation has momentrum
equal to 0.5 * m * v^2, which is 25,000 joules or so. What does this mean? Well, let’s say
that I weigh 100kg (dreaming, I know, but it makes the math easier). If I am travelling 50mph,
then I have virtually the same kinetic energy as that chunk of foam.

I suspect that if you threw me at the Challenger wing at 50mph, something bad would happen.