Archive for October, 2010

The Sadness is Nowhere Near Infinite

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Two things:

– a 500kg-ish pumpkin has passed its ability to stay spherical under its own weight. I imagine someone studies this kind of thing. Yes, they do.

– this is something that is dying to be shot in slow-motion

Hey Bartender

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Buffalo Springfielded

slacktivist: Climate change facts, for what that’s worth

This is a duty, telling the truth. It is the first duty we owe to the truth itself and to every neighbor we meet who is trapped in a lie. Facts matter.

But do not always expect facts to convince. Someone who has arrived at their current stance due to something other than facts will not likely be persuaded to budge from it due to the facts. Some small percentage, some few, are honestly misinformed, and for them facts and information will be persuasive and liberating. They will be grateful for the link. But for most the problem is not simply one of a lack of accurate information. For them, finding their way back to the truth will require retracing the steps that led them away from it — a path that had little to do with information or facts.

Regarding the facts of climate change — and also any other similarly oft-rejected set of facts that cannot reasonably be denied — the denialists can be grouped into three broad categories: 1. The honestly uninformed or misinformed; 2. The liars; and, 3. The deluded.

The facts presented on that NASA site will be persuasive to those who fall into the first category. For them, a clear presentation of accurate facts will be necessary and sufficient.

For those who fall in the latter two categories, a clear presentation of accurate facts will be necessary, but it will not be sufficient.

Disappointed, but not Crushed

I tried going to the rally today, but didn’t make it.

Going into DC always carries with it the question of “where do I park?” and the one definite answer to this is “Work.” Owing to that reason, easy access to the metrorail system (“The Metro”) was never really a consideration for choosing a place to live, but it also means the occasions I need to use it, it’s a time-consuming chore. So I decided that driving in to work and catching the metro in DC was a better option than doing so from home. I hiked over to the Woodley Park station (and since most of you have never been there, let me tell you it’s like you’re descending into the bunker at SAC-NORAD or something. The station is 150 feet below the surface, and the second escalator is 200 frikkin’ feet long.) I bought my ticket and went down to the platform, and then was confronted with this:

All of the cars on all of the trains were packed. I was in the station for a half an hour and it was like this the whole time — one or two skinny people were able to insinuate their way into the cars, but that was it. I held out an irrational hope that the next train would be better, but of course it never was. I finally realized that there was no way of getting to the rally on time or even fashionably late. I had no plan B. (I could have initially chosen to hike to the DuPont Circle station to catch the metro, which wouldn’t have improved my chances of riding, but then I might have been tempted to just walk) Since at this point my net investment in going was only a few hours of my time, and I was not meeting anyone there, I just said fuckit and hiked back to my car and drove home. I went via Rock Creek Park on the way back, which was a nice way to go, and caught the last part of the rally on TV.

That's Doctor Batboy to You

Big Fat Whale: Tabloid Science

Calibration is a Cold Dead Fish

But did you correct your results using a dead salmon?

With the sheer number of images, can certain voxels light up as false-positives? You betcha. Is every voxel significant? Well, to answer that, Craig Bennett and his colleagues took a dead Atlantic Salmon, and placed it in an fMRI. The salmon was then shown a series of photographs depicting humans in various social situations. The (dead, remember?) fish was asked to determine which emotion each individual has been experiencing. They scanned the salmon’s (did I say it was dead?) brain, and collected the data. They also scanned the brain without showing the fish the pictures. The images were then checked for change between the brain doing picture recognition tasks, and the brain at rest, voxel by voxel. They found several active voxel clusters in the (yes, still dead) salmon’s brain.

Overheard in the Lab of the Day

I’ll be gone next month, but I’m not sure of the dates. It will be an admixture of the second and third week.

Pet Peeve of the Day

The wave of pedantry continues.

How is it possible to have two midterms in one class? This bugged me when physics professors for whom I was TA-ing would do it, and I’ve seen a couple of references more recently. A MIDTERM happens in or near the MIDdle of the TERM. It’s right there in the word. As the so-called immortals of Highlander would say, “There can be only one!” If it doesn’t happen then, it’s just a regular ol’ EXAM or a TEST. At least having more than one final exam hasn’t caught on yet, as far as I’m aware.

While I'm In Fist-Shaking Mode …

as I was yesterday, it’s time to stand on the porch and curse the Seebeck effect, which is the phenomenon behind thermoelectric currents. If you take two different conductors and make them touch each other, you get cooties a current if there is a temperature gradient present in the system. You can run this in the other direction and create a temperature difference, which is why thermoelectric coolers/heaters work; this is the Peltier effect and is the technology in most portable active coolers (if it plugs in and doesn’t have a compressor, then it’s probably a Peltier cooler).

Now, imagine you have a vacuum system running an experiment which is very sensitive to magnetic fields. Because you are trapping atoms, you have MOT coils dissipating a few Watts of power (while the trap is on) and you are heating your alkali metal reservoir to facilitate their introduction into the vacuum system. You will have a temperature gradient along your nicely conductive vacuum system. So if you have some dissimilar metals touching the vacuum system, somewhere, you’ll get a tiny amount of current flowing through it, creating a tiny magnetic field. But since such magnetic fields are phenomena non grata, having a thermoelectic connection — which you did not expect to have — is a bit of a pain.

Found it though. Something was inappropriately touching the vacuum system, so we had it arrested and now we make sure there’s a few mils of kapton between it and the vacuum chamber.

In Defense of Physics Pedantry

In yesterday’s Get a Grip, Drew asks a reasonable question in response to my pedantry about the use of terminology:

So when is the word ‘suck’ used appropriately (trying not to sound dirty, here)? Can’t there be a colloquial usage if we know what it actually means?

Used appropriately? Probably never, or rarely. And I have to admit, I can’t think of a situation (on short notice) where this conceptual mistake would cause a problem. We scientists can be rather anal meticulous about terminology, and there is a reason for it. Sloppy terminology might lead one to construct a flawed model of how things actually work, much like when one uses an analogy — there are always circumstances under which the explanation fails to hold. By using the proper terminology, the model is better and there are fewer circumstances under which it will fail.


This is not the only example of the sloppy language phenomenon. Others include heat and deceleration. Heat is probably the worst, and in no small part because physicists are sloppy in using it. To begin with, we present it in two different ways: as a process, by which energy is transferred because of a temperature difference, and also as the energy itself that is transferred. A problem arises when we use the two interchangeably. We then talk of heat flow or heat transfer, which is awkward if we are referring to a process. Beyond that, this reinforces the notion that heat (or, in general, energy) is a substance, as if you could have a little pile of heat somewhere, and heat transfer then invokes the image of pouring this substance from one container to another. The huge drawback here is that the misconception sidesteps thinking about the physical processes of conduction, convection and radiation. Heat (like work) isn’t something in a container, but we reinforce this error by using the term “heat capacity,” which tends to encourage this idea. All of this without even getting into the commonly-held misconception that infrared light and heat are the same thing.


Deceleration is an unnecessary term in physics, because acceleration is a vector, which just makes it a special case where the acceleration and velocity are in opposite directions. But some students have a hard time with the concept of vectors, and decoupling the terminology probably isn’t helpful, especially when you get into circular motion, where there’s an acceleration that doesn’t change the speed at all.


As I said at the outset, I can’t think of the pathway where using “suck” leads one onto the moors of misconception and into the bog of bafflement (not to mention possibly going over the cliffs of insanity), but I’m sure there is one. Because if there is one thing I learned while teaching, it’s not to underestimate the ways in which students will misunderstand concepts.

(edit: I don’t mean this last remark in a bad way — it’s not meant to disparage students. The issue is that if a teacher erroneously assume s/he understands what a student’s misconception is, the misdiagnosis is going to make it harder to fix the problem.)

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