All posts by Chris

why I won’t fly

I don’t fly. Since the TSA put its latest set of security-theater rules in effect, I just can’t do it (or ask my family to) in good conscience.

It comes down to this: I know too many people who would be traumatized by the kind of treatment the TSA has made mandatory. I can think of too many cases where either the backscatter machines or the invasive patdowns would cause lasting damage, the kind no flight is worth:

You get the idea. Privacy is important. For some people, it’s vitally important. And it’s relevant, because I have not committed a crime. Getting on an airplane is not probable cause to believe I will.

Yes, I realize that not all these cases apply to me. I also know that my family won’t necessarily be subjected to the backscatter or the patdown. The point—and to me it’s the only important point—is that no one deserves to be treated this way, and I refuse to support a system that does so.

Each time I choose not to fly, I’ll send a letter to the airline I would have used, the airports I would have gone through, and the TSA to let them know why. I hope that eventually they’ll see reason and do away with these crazy searches. Until then, I won’t fly.

For reasons to stay angry, follow the ongoing news on Reddit’s Flying With Dignity group or get a stream of images from The Daily Patdown.

an analogy for particles with spin one-half

This may seem like an odd diversion, but John asked about it just this morning so I thought I’d share with the rest of the class.

Electrons, in their secret life as wibbly-wobbly quantum particle-wavey things, have a property called spin. To quote a handy article I just ran across:

One of the things that was clear from experiments was that electron have spin. A first naive picture of an electron – this is not an accurate picture but it’s a start – is as a tiny ball with electric charge – which is what flows when a current flows in a wire. If you spin a ball of electric charge, the electric charge goes around in a circle. You effectively have a tiny current going around, and when you have a current like that you have a magnetic field – the electron becomes a tiny magnet. The presence of that magnetic effect is pictured as the electric charge spinning around. If the electron was still, it wouldn’t have this magnetic effect.

It gets better:

Among the many counterintuitive properties of the electron is the fact that it has spin one-half. This is the mathematical way of saying that if you rotate an electron through 360 degrees, it doesn’t look like it did before you started! There is no parallel for this in our everyday world – we are accustomed to being able to turn objects through 360 degrees and get them back to where they started.

Oh, but there is a parallel in the everyday world, or at least in my slightly-twisted mind. Think of it like so:

  1. Imagine a reel-to-reel film projector. Running a short length of film through end-to-end works like you think it would.
  2. Tape one end of the film to the other; now you have a continuous loop of film that repeats itself. This would correspond to a spin of 1, because it looks the same after one loop.
  3. Now tape one end of the film to the other backwards, to make a Möbius strip. The film still loops, but now it does one loop with the frames reversed left-to-right. It doesn’t repeat itself exactly until the film has looped through twice, corresponding to a spin of 1/2.

Does this mean that electrons are actually tiny loops of film? No. It only provides an analogy for this one property, and even then it might not go very far. Still, as soon as someone says “there is no X”, I have to find a counterexample. :)

the rule of telling children anything

I had to post this in response to the flurry of rumors around NASA’s announcement that this Thursday they will “discuss an astrobiology finding that will impact the search for evidence of extraterrestrial life.”

The rule is simple: When you tell a child anything, they will ignore most of it and leave only the words that benefit them.

Toddler version:

No, don’t run into the street.

Blah blah run into the street.

Young child version:

We’ll go to the zoo if there’s time after the store and lunch.

We’ll go to the zoo blah blah blah.

Older child version:

If you clean your room, you can borrow the car on Saturday afternoon.

Blah blah you can borrow the car blah blah.

Journalist version:

NASA will hold a news conference to discuss an astrobiology finding that will impact the search for evidence of extraterrestrial life.

NASA will blah blah discuss blah finding blah evidence of extraterrestrial life.

…and there you go. Good luck on Thursday, guys.

assumptions and their ills

Yesterday I did something dumb, and I only realized it today because I don’t trust an easy success. Let’s see if you can spot the flaw in my reasoning:

Background:

  • A process (X) is run on a series of items in a queue.
  • Items are added to the queue continuously, about 500 per hour.
  • A processor (Z) is started once an hour. It performs X on all the items in the queue, then quits once the queue is empty.
  • If there are any errors, the processor emails them to me after it quits.

The problem:

  1. I noticed 100 random failures in process X each hour.
  2. I hypothesized that X is failing due to intermittent system unavailability.
  3. I checked the hypothesis by looking for clusters of X failures at times of high load. (There were.)
  4. I “fixed” it by pausing the Z processor for 60 seconds whenever there’s a failure (to let system resources recover).
  5. 12 hours after the fix, I got no failure emails and declared victory.
  6. Not so fast: Not only did I not fix the problem, I caused something worse.

Can you figure out what I did wrong? Continue reading

a cat… standing up!

These gentlemen are from the future.

These gentlemen are from the future.

You may have noticed how quiet Global Spin has become, yet again. With the rise of Twitter and Reader and Tumblr and other such thing-share-ers, our little community no longer has much reason to post their thoughts to a group blog.

In response, I’m quitting!

checks notes Oh wait, that’s not it… shuffles papers One sec, it was right here…

Right! In response, I’m going to keep posting the same old things on Global Spin as always. (In a word: monkeys.) I won’t even promise to post more often, because we’ve all seen through that little shadow play. Or something.

For those of you looking for a little more regularity and a little less depth, I give you a cat… standing up! (Oh, and I might also share some other things over there, because it’s what all the kids are doing these days.)

That is all.