# The Mpemba Effect: A Good Case For Citizen Science?

I just read an intriguing article on the Mpemba effect at Skulls in the Stars. Between the history of the effect and the continuing puzzle of what causes it, this is the best example of science-as-a-process I’ve ever seen:

Mpemba made his accidental discovery in Tanzania in 1963, when he was only 13 years old and in secondary school. In spite of widespread disdain from his classmates, he surreptitiously continued experiments on the phenomenon until he had the good fortune in high school to interact with Professor Denis Osborne of the University College Dar es Salaam. Osborne was intrigued, carried out his own experiments, and in 1969 the two published a paper in the journal Physics Education.

So what did Osborne’s research show? He placed a 100 cm³ beaker filled with 70 cm³ of water on a sheet of insulating foam in a freezer, and timed how long it took for the water to freeze. For temperatures up to 20 °C, the time was roughly proportional to the temperature above freezing, up to a maximum of 100 minutes at 20 °C. For higher temperatures, however, the time dropped dramatically, down to 40 minutes for 80 °C water!

Be sure to read the complete article for the whole story, including many attempts to characterize the Mpemba effect over the years. 50 years later there still isn’t a strong consensus about what causes the effect, and in many cases it’s supposed to be difficult to reproduce.

To me, this is crying out for a citizen-science experiment with lots of participants, similar to the way Biocurious works. The experiments themselves are dirt simple (and cheap) to implement; all they really require is water, a heater, and a freezer. The rest is a matter of documenting all the (potentially) relevant variables, including the heater and freezer used, the source of the water, the type of containers, and even the geocoordinates of the experimenter. (Hey, who knows, right?)

A second generation of citizen-science experiments could then be designed based on trends in the first-generation data. The fun thing about this step is that (as Galaxy Zoo has shown) the data often suggests results that weren’t expected before it was being collected. (That shouldn’t be surprising; this is science after all.)

The point of each subsequent generation would be to build more accurate predictions of which experimental setups would or would not produce the Mpemba effect. Eventually it should be possible to make a set of statements like, “Heating 50 ml of 20 °C tap water in a 100W microwave for 90 seconds is 90% likely to reduce the time required to freeze it in a 1 m³ freezer by 35%.”

Why the citizen-science approach? I suspect that rather than trying to control all the known factors to produce the desired result, we instead want to track as many factors as possible to characterize the space of results. This particular effect will probably require a “vast multidimensional array of experiments“* to characterize properly, so enlisting a large number of citizen scientists makes a lot of sense.

Besides, each and every one of the test participants can have fun guessing at the real causes involved. Who doesn’t love a little armchair theorizing?

* Yes, I’m ‘citing’ Wikipedia. The original article cited there is inaccessible, and the rest of the Wikipedia summary is informative stuff.

# this is not a science blog post

I (and Global Spin) have changed a bit over the last few months. Nothing you’d notice much, but I’ve set aside a few projects and picked up a few others. Specifically, I’m starting the long road toward becoming a licensed scientician.

Long story short: Global Spin is shifting towards science blogging. For the remainder of 2011 I’m going to post something sciencey once a week, probably on Tuesdays.

Older posts will still all be here; in fact, I’ve fixed the archives list in the sidebar so it shows posts going back to 2003. However, the focus going forward will be on science, culture, space, and technology. Those four categories catch most of what I’ve posted in the last two years anyway, so it won’t be a big shock.

I’ve also streamlined the site a bit. It’s not a community place anymore; social-media sites are much better at that now. It’s not even a place to store my personal commentary on the rest of the web; Tumblr and Twitter and Reader (oh my!) fit that need nicely.

One thing I’m going to try (and maybe go back on): I’ve turned off comments on these posts. Again, most of the commentary seems to happen elsewhere, so having those empty boxes at the bottom of each post seems a bit archaic. If you disagree, contact me and I’ll reconsider.

The motto hasn’t changed, though: We still protect our freaks.

To Science!

# 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.