Sophomoric MIT student laser work

As undergrads in the late fall of 1969, John and I were both taking an optics course, six point something or other. It required a lab project. Perhaps primed by Star Trek and Mission Impossible, we ambitiously decided to build a long-distance laser communicator.

There was clear line-of-sight from the top of MIT Building 24, looking over the shoulder of the Great Dome, to my 5th-floor apartment on the other side of the Charles, on Mass Ave near Beacon St. At just over a kilometer, that seemed a long enough distance to prove the point. A safely low-milliwatt helium-neon laser (the red kind) would carry our signals. A high-voltage transistor would modulate the laser’s couple-hundred volt input power. (I think we asked first, before we tore into the laser to re-engineer our transistor into the circuit.) Continue reading “Sophomoric MIT student laser work”

H.S. robotics project

This is not a proposal, but a way to communicate just one fevered vision.

Background

It seems a fair assumption that the Robotics Club members are interested in doing some robotics. But maybe they heard “Nope, we’re not doing robotics, not until FIRST in January. The rest of the year it’s just fundraising (collecting old shoes, selling candy bars) and leaning on parents to be mentors.”

Maybe there’s a robotics project that would help with fundraising. That would combine two problems into one solution.

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Competition between scrum teams

An “agile” coach/consultant was brought into to a place where I once worked. Among other things, he said he likes to set up a little competition between scrum teams, with some (undisclosed) reward for the team with the best record of completing all tasks in the sprint, over some period of time. Here’s why I think that’s a terrible idea. Continue reading “Competition between scrum teams”

Ubuntu admin—users and groups

It seems that I do admin for Ubuntu users and groups just infrequently enough, that every time I have to go look this stuff up and decide which to use. So I collected it in one place that I should be able to find next time.  I put it here just in case it might help someone else in the meanwhile.

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There was a Time

There was a time when I could dump my trash out in the woods and nobody could ever notice.

There was a time when I could draw pure water from a river and never know or care how many outhouses—or moose—were upstream.

There was a time when I could burn my autumn leaf pile and my neighbors would only get an aromatic reminder of the season.

There was a time when I could burn coal to heat my stove and the skies remained clear.

There was a time when I could dump my smokestack effluent out into the atmosphere and the wind would dilute it before anyone could ever notice.

There was a time when I could dump all my externalities upon the rest of the world without bothering to account for the infinitesimal degradation it caused.

There was a time when I was given dominion over the fish of the sea, and over the fowl of the air, and over all the earth, and my stewardship thereof preserved it for me and my seed unto all generations. And because I was small, compared to Nature, whatever I did pretty much didn’t really matter in the long run.

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Principle of Indistinguishability

a.k.a. Principle of Indifference:

If you can’t tell the difference, it doesn’t matter.

Some of us have no problem reaching a crisp decision. Right or wrong, they deal with what the job (or life) brings them, deal with the consequences, and carry on.

Others (including this writer) tend to think things through, understand things in depth, carefully identify options and weigh alternatives, seek other opinions, and generally dither about before creeping up to a decision.

Having been accepted to three schools, which one should I pick? Which job offer/marriage proposal should I accept? Is it time to replace my furnace yet? Which TV should I buy? Which commuting route to the office today? Deer in the headlights, squirrel that won’t dash off the road. Should I stay or should I go now? (asked The Clash, covered by Weezer).

When a decision turns out to be a difficult one, generally it’s because the alternatives are pretty much equivalent: they’re equally good, or equally bad. But you know, if they really are equal, then it doesn’t matter which one we pick! The very thing that makes the decision hard to reach actually minimizes the problem of picking the “wrong” one—which should make it easier to decide. Perhaps the psychologists can explain our paradoxical behavior.

A side case is when you lack information that is necessary to make a truly informed decision. Rather than freeze, we can identify the information that would actually change our decision, and seek it—and there is no need to wait for info that would not change the decision. Also, if the consequences of delaying outweigh the consequences of deciding wrong, we have to just close our eyes and jump.

Deciso!

“Average” considered harmful

The vast majority of people have more than the average number of legs.

The average mother has 2.36 children even though no mother has that number.

We have an intuitive grasp of what it means when something is average, typical, or representative.  Math and statistics formalize “average” in terms of mean, median, and mode.  Each of these quantities condenses the complicated details of a distribution into a single number.

That number oversimplifies things, though.  Bizarre, counterintuitive, and seemingly paradoxical things happen with unusual (not-so-representative) distributions.

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