visualization of high dynamic-range data

college: what's the point?

In the State of the Union address of 2011 January 25, Obama raised one of his standard themes, which is the great importance of college education:

If we take these steps—if we raise expectations for every child, and give them the best possible chance at an education, from the day they are born until the last job they take—we will reach the goal that I set two years ago: By the end of the decade, America will once again have the highest proportion of college graduates in the world.

Though I don't disagree that we need to give all Americans great opportunities, I disagree that the best way to achieve that is through universal college attendance.

First of all, as pointed out here and many other places, though employers want to see college degrees, they do not really look for many of the things in a potential employee that college brings. That is, it is not clear that college is delivering useful things to employers. A good example is math skills; even high-tech employers do not look for math skills among potential employees.

Second, since most of the important skills for employers are communication skills, flexibility, problem-solving, and ability to learn (rather than specific content knowledge), employees ought to be well prepared by the end of high school. How can (more than) full-time work for twelve years not be enough to teach 18-year-olds the communication and common-sense skills they need to do most jobs? I realize that schools face huge challenges, but why not make helping the schools the top priority?

Third, and related to the second, the reason Obama and other politicians focus on sending students to college instead of improving K–12 is that college is private. Fixing schools takes public money; sending kids to college takes private money. Even state schools in America charge tens of thousands in tuition, and they don't have the capacity to take up Obama's slack. So requiring all kids to go to college is like levying an enormous quasi-voluntary tax on parents, relieving society of the responsibility of providing opportunity to the less fortunate. If a kid has trouble, in this vision, it is because his parents didn't do right by him.

Indeed, this ties it all together: Abandon the public schools, because improvements there would reduce disparity and improve the public sphere. Require (effectively) all potential employees to go to expensive colleges, because that is tax-neutral and increases disparity! What happened to the common good?

Apollo 11

Pete Mao (Caltech) sent me a note for Newton's birthday, pointing out that all sensible transfer orbits to and from the Moon ought to have half-periods (transfer times) of about 5 days. And yet, as he also pointed out, Apollo 11 came back in 2.5 days. What gives? Did NASA waste fuel to improve the filmic value of the mission, or does the enormous tidal effect of the Sun change the sensible set of transfer orbits for some reason I don't understand?

(His note on this subject also had a nice discussion about what a 5-year-old wants when he or she asks a scientific question, and why just answering it is the wrong response.)

diagnosis

I posted about diagnosis on my research blog and that made me realize that I should post here too. Almost all of science is diagnosis: You must diagnose your code, you must diagnose disagreements between theory and observation, you must diagnose inconsistencies in results. And yet diagnosis is so far outside any formal curriculum, no-one knows what you would even think about teaching there! It is taught to doctors and automobile mechanics, but not astronomers, who need it just as much, or perhaps even more.

Seymour Papert makes this point very clearly—and much more generally—in his book Mindstorms. One of his main arguments that computers must play an important role in education, or in thinking about thinking, is that programming a computer forces us to confront bugs. These require diagnosis (and also lead to interesting insights, a consequence he discusses extensively).

astronomical detectors

Another problem-set problem, inspired by an email today:

Imagine measuring the brightness of two stars, one of which is a 100,000 K blackbody, and one of which is a 3,000 K blackbody. You are interested in the flux ratio in the V band. In one experiment, you perform this pair of measurements with a (flatfielded, calibrated, etc) CCD with a standard V-band filter on it. In another, you perform this pair of measurements with a bolometer with the same filter on it. Do you expect the flux ratio you measure to be the same in the two cases, and, if not, what is the expected difference? Imagine that both detectors are very high in quantum efficiency over the wavelength range of interest, and that you are capable of making accurate, calibrated, sky-subtracted measurements in both cases.

perspective

Future problem-set problem: These two images were taken from the same three-space camera position, with the same digital camera. What, physically, was changed about the camera, and why did it have the effect that it did?

infinite jerk

Last week I worked through some kinematics, and it led to a discussion in lecture about the jerk, that is, the time derivative of the acceleration. I was emphasizing that the velocity must be a continuous function of time (lest we have infinite accelerations and hence infinite forces), but then I realized that most people in the class (physics majors) felt that the acceleration must also be a continuous function of time.

After a bit of thought I agreed with them, but not for the reasons they wanted; indeed several were unsatisfied with my discussion: As far as I can tell, the only thing that limits the jerk is the propagation of information. When you slam on the brakes on your car, it takes a finite time for the brake shoe to come in contact with the wheel. This is not really a fundamental problem with infinite jerk (the jerk appears in no physical law), but in any real situation because information propagation (and other kinds of changes) happen at finite speeds, the jerk can never really be infinite.